Table of Contents

Lesson 1: A note on printing BW with a Color Dichro Head

Even if you are printing strictly BW you may consider using a Color Dichro head. When printing on Variable Contrast papers a Color Dichro head can be a great advantage due to the availability of step-less adjustable filtration.

Kodak, Ilford, Agfa, Seagull and others have issued tables that directly translates Magenta and Yellow filtration combinations into their VC paper grades.

If you use a paper-brand with no published filter combination chart you can use the Ilford charts as a starting point for establishing your own chart.


With the automatic CLOSED LOOP DIGITAL LIGHT Color Dichro heads the tables are not necessary. DIGITAL LIGHT Color Dichro heads has Pre-programmed BW Variable Contrast grade settings built into the electronics. You can choose any VC setting, between grade 0 and grade 5 in increments of 0.1grade.

Using a Color Dichro head for BW can in many cases be a great benefit ✔ Using a Color Dichro head allow you to change filtration in mid exposure without any mechanical problems, such as opening filter trays, light head doors etc. Unwanted mechanical movement can thus be avoided. ✔ Even a manual Color Dichro head allow you to chose your VC filter grades in increments of 0.1, that is you can choose grade 3,5 or 3,6 or 3,7 and so on IF you establish your own chart. ✔ If you occasionally have a very hard negative that would require a cold light source – then it is possible to dial inn the cold light equivalent setting and you are ready to print. ✔ Most Color Dichro heads have more light, and a more even light, than any existing Cold light or Collimated light systems. ✔ A Closed Loop Color Dichro head or SEMI closed loop will automatically calculate the difference in light output associated with the different filter grades – this makes "split filtration" very easy to manage.

Lesson 2: What is Closed Loop and SEMI Closed loop light systems?

CLOSED LOOP is an advanced color (light) metering process. The electronics controlling a Closed Loop Light Head record the actual color of the light in the mixing box. It automatically maintain the requested light level and color by compensating for any fluctuations in line power, lamp, filters etc. Compensation is obtained by adjusting filter position and voltage feed to the lamp(s) in the Light-head. A Closed Loop Light head also compensate for all changes DURING an actual exposure. What does this mean in practice? 1) It enables the operator to accurate repeat a given filter pack. Let us assume that you printed a negative last week with a "filterpack" of 20M and 70Y at an exposure time of 10 sec. When you want to print the same negative again, a week later, a month later or a year later and therefore you ask for that particular "filterpack" (you may even have it stored in a print channel) you are guaranteed that the paper will receive the exact same amount of light with the exact same color quality as it did last time you asked for that particular "filterpack"

Also, if you print large series of prints at one time you are always guaranteed that each print receives the exact same exposure each time you push the expose button.

With a manual head, where you set the filtration on mechanical dials, you very rarely are able to set the dials precisely the same from time to time, and even if you are able to repeat a given setting the quality/quantity of light may still differ due to the lamp getting older, variations in power etc.

Closed loop heads are keyboard controlled. They do not have mechanical dials. Instead of the operator physically operating a mechanical dial, motors react to keyboard, and internal sensor instructions.

A DIGITAL LIGHT heads react to changes within 1/1000 of a second. Durst and DIGITAL LIGHT CLOSED LOOP heads have a minimum accuracy of +/- 0.1 f-stop in Density and of +/- 1 CC color.

CLOSED LOOP has a host of programmable channels, making it possible to store not only paper values but also individual print information. Closed loop light heads incorporate built-in digital timers.

In short – a CLOSED LOOP system reports the actual color (filter value) of the light in use and maintain it at all times, when lamps are on, with motor controlled filters and electronically controlled power supply.

SEMI CLOSED LOOP is in all counts the same as described above. The difference between CLOSED LOOP and SEMI CLOSED LOOP; On a SEMI Closed loop system the operator has to dial in the desired filtration on a set of mechanical dials. The computer (Electronic measuring sensor) measures the exact quality of the light in use and report the measured result on a screen. The SEMI CLOSED system will NOT automatically maintain a certain filter setting – HOWEVER – it will display the ACTUAL color of the light and as such make a given setting repeatable with a tolerance of +/- 1 CC. Some systems will alert you with sound warning if the measured light drifts outside preset tolerances.

You can not store print data in a SEMI CLOSED LOOP System and the timers are not incorporated into the electronics.

A MANUAL DICHRO HEAD indicate the amount of filtration via a mechanical scale. There are no correction for fluctuations in power supply, no correction for change in lamp temperature or any other arbitrary. A manual head does NOT show the actual color of the light in use. The scale on a manual head indicates a mechanical position of the color filter in relation to the lamp.

A manual Color Dichro head is in most cases more than enough for BW printing as hobby or for small print series, and for small printing needs in color.

For the demanding Fine Art Printer who produces large series it is rarely efficient enough.



The light traveling through the negative or transparency in an enlarger, and thus via a lens forming an image, can be delivered to the photographic emulsion (paper) in many different "forms".

The term "forms" embraces such subjects as the directional quality, the spectral properties and the amount of light.

In order to enable our selves to understand how light works, in photography and especially in enlarging, we have to break down the information we have about "light", into small bits.

Light is a visible electromagnetic ray with a certain wavelength, l, and frequency, V. The relation between frequency and wavelength is expressed mathematically as C=l · V, where "C" is the light speed (in a vacuum it is 2,998 · 108 m/sec)

Radiation in the visible spectrum is expressed in "nm" (nanometer= 10-9 meters)

Of all the wavelengths the human eye can only perceive a narrow band (spectrum) from 380nm to 780nm. The eye is most sensitive in the middle of the spectrum, sensitivity peaks around 500nm.

For wavelengths immediately over and under the human perception we use the terms infrared (IR) and ultraviolet (UV) radiation.

High values of Colour temperature – over 3000K – belong to the blue end of the spectrum and low values belong to the red end of the spectrum. We normally associate the colour blue with "cold". Oddly enough when talking about light "blue" is warmer (hotter) than the red light – "Red" being the colour we normally associate with warm.

In the same manner as a human being photographic materials are able to perceive different spectrums of light. And they may also have peaks inside the spectrum they are able to perceive.

Films, BW papers, Type C Color papers and Ilfocrome papers are all sensitive to visible light. The specific sensitivity differs from material to material. Some materials are more sensitive to one color than to another which would be the same as saying that; their sensitivity peak at different places within the spectrum they are sensitive to. This is how the manufacturer controls the physical properties of their paper, contrast, color etc.

In addition to being sensitive to visible light most materials are also sensitive to UV and IR radiation. The specific sensitivity to these wavelengths differ from material to material. Because the are sensitive to the same spectrum as the human eye they must be handled in total darkness, or under safelight designed for the material in question.

Most color papers are fairly sensitive to UV and manufactures of advanced Color heads use heat filters that restrict both UV and IR light waves in reaching the paper during exposure. IR radiation is also known as "heat rays".


The sensitivity curve on the right is an example of Kodak of Type C paper sensitivity. From this example it is obvious that this particular paper is sensitive in the visible spectrum, it is sensitive from 390nm to 750nm. It is also clear that it is not equally sensitive throughout the spectrum, it is more sensitive to blue light than to red light.



The sensitivity curves on the right are for Ilford MULTI GRADE fiber-base paper and for ILFOCHROME (CIBACHROME) paper.

IMAGINE the spectral sensitivity curves for a photographic paper super imposed on top of one of the spectral emission curves for lamps, shown below, and you will start to understand why certain lamp types does not work with certain papers (photographic emulsions) and also why certain types of safelight does not harm certain papers.



Our eyes and photographic emulsions are sensitive to different spectrums of light. Lamps of different kinds emit energy (light) with different spectrums. Some lamps have peaks in their spectrum.

Daylight, incandescent lamps and tungsten-halogen lamps emit a continuous spectrum – the spectral efficiency curve is unbroken = without peaks.



Both incandescent lamps and tungsten-halogen lamps produce the major part of their radiation (emission) in the "red" (IR) end of the spectrum. As a matter of fact only 8-9% of the total energy used by a tungsten-halogen lamp is transformed into visible light. More than 80% is turned into heat (IR) and the rest is either lost in the process or emitted as UV. UV emission from an incandescent or tungsten-halogen lamp is normally below 2%.
This explains in particular the necessity for heat filters but also for UV filters in enlarger heads.



Fluorescent lamps and metal-halogen lamps have broken sensitivity curves – that is; they emit some light in the entire visible spectrum but the major of their emission are in narrow bands. See examples on your right.

By examining the emission curves for fluorescent lamps and the spectral sensitivity curve for the Ilford Fiber base paper- above – you will find an explanation as to why some printers have run into problems with their "cold-light heads" when using BW-VC paper.

Maybe you have tried to photograph on color film under fluorescent "daylight" type lamps and have been surprised to find your transparencies with a strong cyan/green color cast. This is caused by the fluorescent lamps having a spectral emission different from what is understood by the film as "daylight". Which essentially is the exact same problem printers run into with certain types of "coldlight heads".

The spectral sensitivity for ILFORD Fiber Base paper is very high even below the visible spectrum (380nm) and maintain that sensitivity up to 525nm where it drops of drastically and basically it is not sensitive at all above 550nm.



If the neon tube in a given cold light head had the same spectral sensitivity curve as the 4000K tube, on the right, it would be almost impossible to get an exposure on the paper because this tube peaks right at and above 550nm. And has very little emission, apart from UV, in the spectrum where the paper is sensitive.

As a matter of fact all three tubes would be poor for Ilfords paper which is obviously designed for Tungsten or Tungsten-Halogen light.

Of the three fluorescent lamps the middle tube would be the tube best suited for platinum printing and other UV printing due to the very high emission in the UV area.

As you will see from the spectral emission curve for a Phillips safelight lamp (below) it's emission has been modified to cover an area above 600nm. An the emission in the 600nm area is at its lowest with most emission in the area around 700nm where (Ilford) photographic paper is least sensitive and the human eye still able to perceive the emission.

The color of light is expressed as "The color temperature" and it is measured in Kelvin (K). Degree Kelvin is an absolute temperature scale contrary to Degree Celsius. TK = TC + 273.

The colour of light = colour temperature can be described very precisely with a set of coordinates (X,Y), in a diagram called a "Chromaticity diagram". This diagram is internationally recognized and is becoming more popular in photography and repro-photography, scanning etc. as a universal standard.

It is important to understand that two light sources can have the same colour temperature but at the same time completely different spectral effect distribution. This is obvious when comparing the spectral emission curves for Fluorescent lamp, with a colour temperature of 3200K, to a Halogen lamp with the same colour temperature.

Like sound waves, light waves can be manipulated, modified and transformed into forms needed for a given purpose, in this case printing with an enlarger.

We can mix light. The light beam from two light sources – two bulbs - each with different spectral emission characteristics can be mixed to form a third "light source" with a spectral emission curve different from the two "source" lamps.

We can also modify a light source by filtering. IMAGINE a sheet of green fabric as a crude filter. If this "filter" is inserted into a beam of light, the light on the "beam side" of the fabric will have different characteristics (colour) than the light that penetrated the fabric/filter.

One thing we cannot do – we cannot ad to a light source where nothing exists to be added. We cannot ad a dye, if we want to obtain light in a colour different from that of a given light source. No such dye exists for practical use. (Light experts will argue that the light emitted from neon tubes are dependent on powder (dye) that can be mixed to create different spectral emission curves for a given tube.)

The only way we can change the "colour" of an existing light source, by adding to this given light source, would be to add emission from a lamp emitting the spectrum/colour that we would be trying to obtain. And even then we would still end up with a "colour" different from the "colour" of both our "source" lamps because our new light source would be a mix of the two source lamps. To predict a certain outcome from combining two light sources would be a very time consuming and highly theoretical calculation.

The only practical way to change the colour of an existing light source, in a predictable manner, is to manipulate the light with a filter. A "filter" is whatever will give you the result that you are trying to obtain. It can be anything from a coloured fabric, to a very advanced piece of glass with properties that can alter the light in question.

Most light sources are considered "white-light-sources". A "white-light" light source is a light source emitting a spectrum (mixture of) light that the eye perceive as balanced – neutral. White light consists of a mixture of red, green and blue light waves. We have to remove a section of the total spectrum in order to create the colour-spectrum we want, if only one light source is available for the purpose.

If we manipulate our light beam by introducing Red, Green and Blue cut-off filters in the light beam we would be using the so called Additive filter System.

If we remove the yellow portion of a "white light" beam, by introducing a blue additive filter in the light beam, the resulting colour left would be Blue = Magenta + Cyan.

If we remove the Cyan portion of the "white light", by introducing a Red additive cut-off filter in the light beam, we are left with Red = Magenta + Yellow.

If we stack a Red, a Green and a Blue additive cut-off filter on top of each other we would in theory block out all light. (In reality some light still leaks through.)

If we manipulate a light beam by introducing Cyan, Magenta or Yellow cut-off filters in the light beam we would be using the Subtractive filter System.

If we remove the Red portion of a "white light" beam, by introducing a Cyan Dichroic Filter in the light beam, the resulting colour left would be Cyan = Green + Blue.

If we remove the Green portion of the "white light", by introducing a Magenta Dichroic Filter in the light beam, we are left with Magenta = Red + Blue.

If we remove the Blue portion of the "white light", by introducing a Yellow Dichroic Filter in the light beam, we are left with Yellow = Red + Green.

Contrary to common belief we also block out light if we stack a Cyan, a Magenta and a Yellow cut-off filter on top of each other. If we introduce equal amounts of Cyan, Magenta and Yellow we block off light in an amount equal to the numerical value of one of the three colours. Ex. If we introduce 30cc Cyan, 30cc Magenta and 30cc Yellow into a light beam we will block out 50% of the available light, because 30cc of each of the three colours together make up 30cc ND – which in photographic terms are equal to one f-stop.


All of the above basic knowledge for all colour printers.

After having been through the study of Spectral sensitivity Curves and lamp spectral emission curves we will immediately understand the transmission curves on the next page.

Those are the actual transmission curves for the three Subtractive filters (Cyan, Magenta and Yellow) from a DURST- DIGITAL LIGHT Colour Dichro head.

Take a look at the curve for the Cyan filter. It blocks light above 620nm, which is the red spectrum and thus it creates a Cyan light source.

The Magenta and Yellow cut-off Dichroic filters work in the same manner. The Magenta Dichro filter blocks the spectrum from approx. 400nm to approx 620nm. And in that manner it creates a Magenta "light source" by transmitting the red and the blue portion of the spectrum. The Yellow Dichro filter blocks everything below 520nm which is the blue end of the spectrum and creates a Yellow light source.

Just as we could remove one of the three primary colours, Red, Green and Blue we could also have removed one of the three secondary colours, Cyan, Magenta and Yellow by inserting a combination of two of the subtractive filters simultaneously. If we insert equal amounts of Magenta and Yellow Dichro filters into a light beam we will create a red light because we block out everything above the red spectrum.


A more detailed study of the spectral properties of Dichro Filters show that, by using a "Color Dichro Head", with a set of Subtractive filters, we are in fact able to create a light source with a characteristics that will suit almost any photographic emulsion. Due to the low UV emission a Modern Color Dichro Light-head is obviously not well suited for those emulsions sensitive mainly to UV radiation.

It can also be argued that a "Color Dichro Head" is not able to imitate a neon tube ("Cold-light-head"). That is of course true when talking about the high UV radiation emitted by most neon tubes, but it is in fact possible to create a "filter pack", with a Color Dichro head, that will create a light source with an emissions VERY similar to the emission of the type of neon tubes / fluorescent tubes used in so called "Cold-light-heads".



After having examined the physical properties of light – colour and spectral emission – we can finalize this study by examining the quantative properties of light.

Most people naturally understand that we can concentrate and focus light in a beam – and they use it daily without thinking about it, placing a lamp shade on a regular household lamp is in fact a manipulation of light rays. The light ray emitted from the lamp bulb is concentrated, diffused and filtered all at once by placing a lampshade over it. Concentrating a light source can be very power full. Just think of the experiment we all made in school with a magnifying glass, the sun and a piece of paper.

We can also bend light rays. With a mirror we can make light rays bend around a corner.

When you see your self in the mirror it is in fact proof that light rays can bend by using a shiny (reflective – mirror) surface. The light rays reflected off you face hits the mirror and is reflected back to your eyes.

Both concentration and reflection is used heavily in modern light sources for enlargers. The light is bounced off mirrors and reflectors with different properties creating a light source that is either concentrated or spread out. How this works exactly is explained in detail in a chapter under DURST & DIGITAL LIGHT Color Dichro Heads.

One little detail needs to be discussed here. If you have ever worked with artificial light in a studio situation, you know that the brightness / intensity of a lamp drops drastically when the distance from the light source to the object is increased. As a matter of fact if the distance is doubled the intensity is reduced to 25% of the value it was at the closer distance.

With other words – if you measure f45 on an object lit by a lamp standing one foot away from the object you would measure only f32 if the lamp was placed 2 feet away.

If the lamp was placed 8 feet from the subject you would read only f8 equal to 3%, - the light would be reduced with 5 f-stops.

We pointed a lamp into a "mixing box" 12 inches (1 foot) deep, and read f45 off a piece of white acrylic that we had placed in the opposing end of the mixing box. (A mixing box is a box lined with a reflective surface, or in this case a mirror, and having a piece of white acrylic (type 0.6) covering two opposing sides (ends)). We the repeated the experiment with a mixing box 8 feet long. This time the lightmeter read f32 2/3. This is a reduction of only 1/3 f-stop.

Our experiment proved that we can in fact direct, concentrate, bend and manipulate light rays.

In addition to concentrating light with the use of mirrors and reflective surfaces we can also concentrate or spread light with the use of a lens.

Finally we can "break" the light. By introducing either a physical obstruction or a "Multi-reflective" (broken) surface we can break a heavily concentrated light beam into a myriad of light-rays. This is called diffusion.

A crude diffuser could be a very fine mesh of either cloth, plastic or metal. Imagine the sun shining through the screen door.

We can also diffuse the light with a lens. If we shine a light beam through a magnifying glass we can move the magnifying glass forth and back and manually focus the light in a very concentrated beam. But we can also diffuse the light by intentionally moving the magnifying glass to an "out of focus position". We can bring the light beam so far out of focus that the light beam will be reduced to a large circle of flare.

We can further increase diffusion through a lens by making the focal length infinitively small and by reducing clarity from the glass used in the lens.

A piece of ¼" thick Plexiglas is a "lens" with a very very small focal length. By adding a "milky white" coloring to the Plexiglas we have in fact created the perfect diffuser for light.

Finally we can restrict the amount of light emitted from a light source. We can of course do it mechanically by introducing an aperture, a metal diffuser or metal grid or by introducing a filter with ND (neutral density) coating.

But we can also do it electronically or electrically by restricting the amount of current supplied to the lamp. (this particular subject is covered under the digital light subject.)

Light can be manipulated in thousands of different ways. Light sources can be created in thousands of different ways.

In photography all "lightheads" belong to one of two groups. They are either categorized as "SOFTLIGHT HEADS" or as "SPECULAR LIGHT HEADS" (also called Collimated light-heads)

Most all light heads (Cold-light-heads, VC heads and Color Dichro heads) belong to "Soft-light" group.

To my knowledge only one type light source, for optical photography, belong in the second group, "Specular Light heads", and that is the Condenser head. A condenser head can produce several different degrees of focused light by varying the lamp producing the light beam, the quality of the condensers, the distance between the condenser-elements etc. A point light lamp will produce a more focused light than an Opal lamp source. A coated condenser will produce a more focused light than an uncoated condenser etc. The different combinations all deliver light of different degrees of collimation.

Of all the different types of Light-heads for optical photography (enlarging) the condenser head must rank as the most versatile light head available. This remark is bound to raise an eye brow here and there and possible a "gasp " in some places.

Let me therefore defend that remark right away.

A condenser head is capable of emulating all other types of light heads available for enlarging. ✔ It of course delivers collimated light of varying degrees. ✔ It also is capable of producing soft light of varying degrees. ✔ It can be used for Color printing as well as for BW printing. The Condenser head may not be as practical 1 for Color printing as a Color Dichro Head, but it can do it.

No other light head is capable of delivering all four features.

Not the Color Dichro Head – it cannot produce Collimated Light.

However, so far, the COLOR DICHRO head must rank as the most advanced light source. It is capable of emulating all types of light sources in it's group. And it is capable of doing so in an efficient and rational manner.

Jens J Jensen, December 2000.

Literature list:
  • Electric light sources by The Danish Society of Light technique.
  • Phillips, Holland.
  • Osram, Germany
  • Andover Corp.
  • Post Exposure by CTEIN.
  • Photographic Sensitometry by Todd & Zakia.


Whether you are a commercial lab or a fine Art Photographer YOU know that YOUR time is too valuable to waste on technical issues. Your time is too valuable not to be able to concentrate on the creative process of printing

Many photographers struggle with old and obsolete equipment. With sheer "mindpower" and concentration they manage to produce wonderful prints by overcoming the restrictions of their equipment.

IMAGINE what YOU could obtain by being able to concentrate solely on your IMAGE.

IMAGINE what it would free of artistic energy if you were able to produce just two more prints per print session. And then think "Twice as many" and see what that will do to your daily work, and the quality of your life.

IMAGINE how much further you could get in a year by using the right tool!

When you buy an enlarger from World Images Inc. / DURST-PRO-USA it is delivered assembled and adjusted with a 5-year WARRANTY - ready for use – just lift it in to your darkroom and start printing. There will be no need for expensive hidden repairs and no need to scavenge for weeks for missing parts.

And it is efficient; it delivers even light, fast exposure times, easy operation and precise focus and alignment. (Alignment is a largely overseen issue, see a discussion under lenses later in this paper.)

We at DURST-PRO-USA will be no further away than the nearest phone – ready to answer your technical questions – free of charge as long as you desire before AND after the sale.


Lesson 5: Alignment of enlargers

If you are struggling for ALSO the best technical result in your prints you cannot ignore the new PROLA alignment adjustable lens board.

Since the introduction in January of 2001 more than 800 units are sold.

Did you know that any enlarging lens would deliver the highest resolution full open? That is; it will produce the sharpest print on the maximum f-stop for the lens in question, for a 150mm Rodagon that would be f 5.6.

This fact is also documented in the instructions manual for APO EL NIKKOR lenses. Here the manual prescribes that the APO-EL-Nikkor can only be used for optimum results full open.

Stopping down an enlarging lens has only one real purpose and that is to increase the depth of field and/or the size of the circle of coverage. Increasing depth of filed, when enlarging, has only one purpose. The purpose is to compensate for misalignment in the enlarger or the negative holder. The negative is so thin, and not three-dimensional, that if it were to be placed accurately in front of the lens stopping down would have no purpose.

Stopping down to increase the size of the circle of coverage for a given lens is a valid reason but the problem can easily be overcome by using an enlarging lens of sufficient focal length, or quality.

Whether you stop down to increase the depth of field or the circle of coverage you pay a high price. Stopping down will deteriorate actual sharpness and often also local contrast.

Durst enlargers are among the most precise enlargers on the market and most often alignment is perfect, and by far enough for the average user. However, competition among user of Durst enlargers is becoming fierce and every little bit of quality is getting important.

The new PROLA lens board will allow you to adjust alignment at the lens stage to 1/100 of one millimeter – which is roughly equal to 1/2000 of one inch.

What is "alignment"?
If you look up synonymous for alignment, you will see words such as arrangement, position and configuration.

Aligning an enlarger is to obtain parallelism between three planes (negative, lens and baseboard) in a 3-dimensional space.

With other words it is desirable that the three planes be parallel not just along and X-Y axis (Right–left and front-back) but along an infinite number of lines radiating out from the center in a flat plane. Fig. 2 show three planes being absolute parallel to each other and also centered correct.

Fig. 3 show one of an infinite number of possible positions where the three planes are out of alignment. It is also possible for two planes to be correctly aligned and the third stage to be out of alignment.

Alignment is also making sure that the center of the lens is correct centered on the negative, see Fig.1

WHY ALIGN the enlarger?
Perfect rendering of shapes are only possible with perfect alignment.

Perfect sharpness from corner to corner is only possible with perfect alignment.

When perfectly aligned, the enlarging lens can be used at it's optimum f-stop. It is no longer necessary to stop down in order to obtain sharpness on the entire negative at the same time.

Alignment of a Durst Vertical L184 enlargers:
As a basic rule we consider the negative stage our "Ground Zero" or "Our starting point".

First make sure that the negative stage is correctly positioned in relation to the chassis – this is best done with a regular level. Secure the negative stage by fastening all bolts and by making sure that the lock knob is in zero position. This is done by:
  • Turn knob #47 (pg. 13 in operating instructions) to position "90 degree" , the last portion of the turn may be tight - that is normal. You will see the pin being pushed out towards the handle.
  • Turn the entire camera a few degrees. JUST a FEW degrees.
  • While camera is turned a FEW degrees turn knob #47 back towards "F" and set it a the "F" position.
  • Turn camera back to zero position and listen for audible indication that the lock pin is engaged correctly. Having set the knob at the "F" position will allow the pin spring mechanism to push the pin into the "zero-position" slot.
  • Secure the "Zero position" by tightening the knob - this is turning knob #47 entirely towards "L".
  • Now assuming that the camera is in zero position:
  • position your alignment tool in such a manner that you can align the baseboard to the negative stage. (Do not align the baseboard to the lens, the correct procedure is to align the baseboard to the negative stage and then aligning the lens to the baseboard.)
  • Correct alignment either by shimming the baseboard or by using the four pre-installed alignment screws (Alignment screws only appear on units delivered by WORLD IMAGES, INC.) You will have to remove the lens holder to carry out this operation.
  • Assuming that the baseboard is correctly aligned to the negative stage the next step will be to align the lens stage to the negative stage. This is best done using the PROLA lens-board system. Aligning the L184 lens stage in a "LEFT to RIGHT" direction is done on the two Phillips screws on the front of the lens stage, to the right of the round center. Unfortunately the lens stage on a Durst L184 can only be corrected for alignment in one direction, that is the "Left to Right" direction when standing in front of the enlarger. Before you adjust this direction make sure that the lens stage is not sagging with the front edge. If sagging, make sure that bolt # 53 (Service manual picture 13) is as secure as possible while still allowing the lens stage to tilt and engage in zero position.
  • The sequence is very important.

If further alignment adjustment of the lens stage is necessary, we recommend using the professional PROLA lens board system. The PROLA has alignment adjustment possibilities, via three set screws, built into it.

The drawing below shows the principle of aligning the negative stage to the baseboard. Fig.3 indicates an out of alignment situation and Fig.4 indicates a correctly aligned enlarger setup. The alignment tool used here is a Linhof Alignment tool using two mirrors and a series of prisms.


Prepare a piece of clear film with a ruler from corner to corner. Simply draw a line on the film and divide it in suitable increments. It is recommended to use a piece of film the size of the largest format that the enlarger (Negative holder) will accept. Position the film in the negative holder with the rulers positioned in such a manner that the intersection is positioned exactly in the middle of the negative holder.

Project this piece of film with a lens to short for the format, say a 150mm lens for a 10x10" negative holder, make sure that the lens coverage show the same number on the ruler in all four corners.

(The illustration below is an approximation.)


Manufacturers of Cold light heads propose that the film manufacturers recommended exposure and development, for a given BW film, should be extended approximately 30%. Some even recommend a 50% increase.

In this context it is an interesting detail that many fine art printers, teachers and textbooks recommend to reduce film speeds to 50% of the manufacturers recommended speed – that is one f-stop overexposure. Fred Picker from Zone VI even suggests rebuilding your light meter to show one f-stop less light than factory intended.

I am sure these recommendations are entirely due to the fact that those giving the advice is using a diffused-light head for enlarging.

Extended exposure and development of negatives produced for diffused-light printing is necessary in order to obtain a level of exposure and contrast capable of producing a normal contrast range on a "grade 2" paper as compared to a CONTACT print.

With other words; It is necessary to modify the film manufacturers optimal exposure and optimal development data in order to make the negative suitable for diffused light printing.

That is a true oxymoron.

At first the manufacturers (and users) of Cold light heads praise this light source for its ability to suppress grain and dust and then it is recommended to overdevelop the negative, which in return will increase grain and decrease detail in the negative.

It is common knowledge that exposure increased above the level recommended by the manufacturer will decrease the resolving power of a given film.

As a matter of fact an "under exposed" film will have greater resolving power than a correctly exposed film.

Any one disputing that as a fact only need to put a 200 ASA standard color film in a 35mm camera and shoot a series of nine exposures from –4 over N to +4 f-stops overexposure. And have the film developed in the nearest one-hour kiosk. You will immediately see that details decrease with the increased exposure. As soon as you enter in to "over exposure" also the grain increase drastically.

Some experts will claim that the loss of resolving power, resulting from the increased exposure, will be countered by the increase in edge-contrast created by the prolonged development time necessary for BW film processed for diffused light heads. I disagree with that argument when talking about pictorial images. There may possible be grounds for that argument when judging purely technical images such as pictures of resolution charts. Resolution charts do not take into consideration tonality. Furthermore high contrast edges on the grain is to be avoided when the grain is located in white or light gray areas.

Clearly no one will dispute the fact that both increased exposure and increased development results in a more defined grain structure.

The effect of increased exposure and development is that:
  • more silver halides are exposed than needed
  • the silver actually exposed is made less transparent.
  • The silver grains actually exposed starts to "bleed" and "Clog".

A single grain of silver can only "absorb" a certain amount of exposure. When it has received its maximum amount of exposure and its maximum amount of development it becomes inactive and further increase in density (on the film) can only be obtained by effects known as "bleeding" and "clogging".

Bleeding is what happens when a silver grain already saturated is bombarded with more light waves, the exposure starts to flow over to the next lower level of unexposed silver halides.

Clogging is what happens when two grains of silver, located next to each other receives enough exposure and enough development in order to bleed into each other.

Let me try and explain that in a more graphic way; IMAGINE that you were to photograph TWO tiny tiny dots (.) The dots are white and placed next to each other in the middle of a large piece of completely black paper or fabric. The distance between the two dots is equal to the diameter of one dot.

The film manufacturers recommended exposure and development would produce a negative in which the two white dots would receive just enough exposure and development to reproduce as two white dots with the same density, as the two original dots, when the negative is contact printed. And just enough exposure and development for the black paper to reproduce with the same density as the original black paper when the negative is contact printed.

It is very important to be aware that published film speeds and processing times, for a given film, are designed to produce a negative suited for contact printing. The type of light used to make the exposure also influences the physical quality, sharpness and contrast, of a CONTACT print. However the differences are minute and I have chosen not to take into account this aspect in this discussion.

Now let us IMAGINE that we overexpose and over develop a second negative shot of the two dots. This time we give the negative half an f-stop more light and 30% more development than the manufacturers recommendation.

The increased exposure would allow silver grains around those actually producing the white dots to also start picking up light, and thus ad to the size of the dots.

The increased development would not only increase the density of the two dots it would further ad to density of the silver grains picked up around the actual image of the two dots.

Before you know it, each of the two tiny dots would have grown 50% and would thus have become ONE larger oblong looking white dot.

You can make a very easy experiment that will show the effect of "bleeding" and "clocking". Put a single hair in your enlarger (any enlarger will do) and make a print where the hair is clearly defined. Then gradually increase exposure or development and you will see at first that the hair starts to look fuzzy and then it will disappear completely and you are left with a completely black print.

Extended development also diminish tonal separation. When development is extended values that would normally be placed lower on the curve are pushed up in the area of the curve where no separation is possible. This effect and the increased grain is particular noticeable in a print/negative with normal shadows and white clouds on a blue sky.

A minimally exposed and developed negative is always to be preferred.


This service must be carried out by an authorized Durst technician. If customer attempts this adjustment warranty is void and the adjustment is entirely on customers own risk / expense. Please read the entire document before attempting any adjustments.

This service repair involves personal risk of high current chock! (220 volt / 10amp)

  • Disconnect mains to both enlarger and EST1000 power supply
  • Remove lamp exhaust cover from CLS1840 – exposing the lamp socket
  • Connect a voltage meter, it MUST be a true RMS meter to the porcelain lamp socket, if wires are not exposed enough to connect the voltmeter it is possible to measure on the two screws located in the recesses in the porcelain connector (cube). Voltage can only be read between neutral and phase. See picture #2
  • Remove the cover of the EST1000 power supply
  • Make sure that all cables are correctly fitted – refer to manual if necessary.
  • Re-connect mains power
  • Turn on the EST1000 power supply and the enlarger if your enlarger is an L1840 chassis
  • Turn on the focus light – the lamp must be on for this test.
  • The voltage meter should show a voltage supply of approx 120 volt RMS. If this is not the case adjust the voltage supply on the P1 potentiometer on the main print board, see picture #3.

The measurement MUST be taken off the lamp holder. The stabilizer circuit must be charged. As this is a phase angle controlled AC voltage, a true RMS meter MUST be used.

DURST-PRO-USA, Inc. recommend setting the output voltage (Step 9) to ONLY 118 volt. This is approx. 2% below maximum and will not effect light output significantly however it WILL extend the lamp life with almost 100%. See below.

DURST-PRO-USA, Inc. recommend setting the output voltage (Step 9) to ONLY 118 volt. This is approx. 2% below maximum and will not effect light output significantly however it WILL extend the lamp life with almost 100%. See below.

Lesson 8: SHIPPING and receiving

Please scroll down to see interesting 2006 and 2007 delivery examples, from actual deliveries.

We ship and pack like we were to receive the equipment our selves. We ship and pack with care, we make sure that all parts are padded and packed in a manner that will GUARANTEE that it arrives at your door step unharmed in a condition that we can be proud off.

We crate in plywood.

We ship air freight only for our enlargers. We ship enough each year to obtain air-freight rates as better than trucking rates.

If a machine is to large to ship air-freight we deliver on our own truck.


Top; a container load is arriving from Durst in Italy. Middle row; Three Durst Hl2506 AF enlargers waiting to be shipped to customers. Bottom row; a custom built Horizontal enlarger is being shipped in a wooden crate to Charles Griffin Lab in NY.

Mr. Henry McNair is receiving a Durst L184 w/condenser head. It is being delivered by our own team. There were two deliveries in California and we rented a Penske truck and delivered and installed our selves. The delivery seems very bulky, please take into consideration that everything is expertly packaged in foam packing material. After unpacking and assembly it will be much less bulky.

Scroll down for more deliveries.




Lesson 9: Condenser combinations for 5x7" Durst Condenser head.


Focal length of lens, mm(inches) Nominal negative size, mm (inches) Linear magnification Mm. Max. Condenser comb. Top Bottom Minimum. diameter lamp, mm 240mm 9½" 130 X 180mm 5X7" 1.7X 4.4X 240 240 110 0.9X 1.7X 240 R 240 210mm 8½" 130 X 180mm 5X7" 1.2X 5.3X 240 240 0.7X 1.2X 240 R 240 180mm 7⅛" 100 X 150mm 4½X6½" 3.2X 6.6X 240 200 0.5X 3.2X 240 240 150mm 6" 100X150mm 4X5" 1.0X 8.5X 240 160 90 0.4X 1.0X 240 240 135mm 5¼" 85X100mm 3¼X4¼ 1.0X 9.5X 240 160 0.4X 1.0X 240 240 100mm 4" 65X90mm 2½X3½" 0.3X 2.4X 240 200 2.4X 13.0X 240 130 80mm 3⅛" 60X60mm 1¼X2¼" 0.6X 17.5X 200 130 60mm 2⅛" 40X40mm 1½X1½" 2.9X 23.5X 130 85 65 50mm 2" 24X36 35mm 3.8X 28.5X 130 85


Focal length of lens, mm(inches) Nominal negative size, mm (inches) Linear magnification Mm. Max. Condenser comb. Top Bottom Minimum. diameter of lamp, mm 240mm 9½" 130 X 180mm 5X7" 1.7X 4.4X 240 240 110 240mm 9½" 130 X 180mm 5X7" 5.3X 21X 240 240H 180mm 7⅛" 100 X 150mm 4¼X6½" 6.6X 26X 240 200 150mm 6" 100X150mm 4X5" 8.5X 30X 240 200 135mm 5¼" 85X100mm 3¼X4¼ 9.5X 39X 240 130 90 100mm 4" 65X90mm 2½X3½" 12.0X 45X 200 130 80mm 3⅛" 60X60mm 1¼X2¼" 17.5X 65X 160 130 60mm 2⅛" 40X40mm 1½X1½" 23.5X 92X 130 85 65 50mm 2" 24X36 35mm 28.5X 102X 130 85


Focal length of lens, mm(inches) Nominal negative size, mm (inches) Linear magnification Mm. Max. Condenser comb. Top Bottom 240mm 9½" 130 X 180mm 5X7" 2.2X 4.4X 240PT 240T 0.9X 2.2X 240PT 240PT 210mm 8½" 130 X 180mm 5X7" 2.1X 5.3X 240PT 240PT 0.7X 2.1X 240PT 240PT 180mm 7⅛" 100 X 150mm 4½X6½" 1.2X 6.6X 240T 240T 0.5X 1.2X 240T 240T 150mm 6" 100X150mm 4X5" 2.5X 8.5X 240T 240T 0.8X 2.5X 240T 240T 0.4X 0.8X 240RI 240T 135mm 5¼" 85X100mm 4¼X4¼ 1.6X 9.5X 240T 240T 0.7X 1.6X 240T 240T 0.4X 0.7X 240RT 240T 100mm 4" 65X90mm 2½X3½" 0.3X 0.6X 240PT 240T 0.6X 2.0X 240T 200T 2.0X 5.0X 240T 130T 5.0X 13.0X 200T 130T 80mm 3⅛" 60X60mm 2¼X2¼" 3.6X 17.5X 160T 110T 1.3X 3.6X 200T 130T 0.8X 1.3X 200I 160I 0.6X 0.8X 240T 160T 60mm 2⅜" 40X40mm 1½X1½" 4.0X 23.5X 130T 85T 2.9X 4.0X 130T 85T 50mm 2" 24X36 35mm 3.8X 28.5X 130T 85T


Focal length of lens, mm(inches) Nominal negative size, mm (inches) Linear magnification Mm. Max. Condenser comb. Top Bottom 240mm 9½" 130 X 180mm 5X7" 4.4X 22.4X 240PT 240T 210mm 8½" 130 X 180mm 5X7" 5.3X 8.2X 240PT 240T 8.2X 20.5X 240T 240HT 180mm 7½" 100 X 150mm 4¼X6½" 6.6X 13.5X 240T 240T 13.5X 27.2X 240T 240HT 150mm 6" 100X150mm 4X5" 8.5X 32.5X 240T 200T 135mm 5¼" 85X100mm 3¼X4¼ 9.5X 42.0X 240HT 200T 105mm 4⅛" 65X90mm 2½X3½ 11.8X 47.0X 240T 130T 100mm 4" 65X90mm 2½X3½" 13.0X 45X 240HT 130T 80mm 3⅛" 60X60mm 2¼X2¼" 17.5X 75X 160T 130T 60mm 2⅛" 40X40mm 1½X1½" 23.5X 104.0X 130T 110T 50mm 2" 24X36 35mm 28.5X 116.0X 130T 110T

Lesson 10: Condenser combinations for Durst 8x10" condenser head

Table of condenser combinations for the Durst Laborator 184.

Lens f = mm / inches Negative size
mm / inches Linear magnification
minimum maximum Condenser Combination +LAZUC0 181 Position of mirror lever Condenser position. 360/14 200x250mm 8x10" 0,9x 2,5x 380 380 H = REAR POSITION 300/12 200x 250mm 8x10"
180x240mm 6½x8½ 0,6x 1,3x 380 380 H = REAR POSITION 1,3x 2,8x 382 380 V = FRONT POSITION 2,8x 4,0x 380 380 V = FRONT POSITION 240 9 ½" 130x180mm 5x7" 0,4x 1,3x 380 380 H = REAR POSITION 1,3x 5,0x 380 250 H = REAR POSITION 210 8½" 130x180mm 5x7" 0,3x 1,lx 380 380 H = REAR POSITION 1,lx 3,0x 380 250 H = REAR POSITION 3,0x 6,2x 380 252 H = REAR POSITION 180 7⅛ 100x150mm 4¼X6½" 0,3x 0,9x 380 380 H = REAR POSITION 0,9x 6,0x 380 252 H = REAR POSITION 6,0x 7,5x 250 252 H = REAR POSITION 150 6 100x125mm 4x5" 0,25x 0,7x 380 380 H = REAR POSITION 0,7x 2,5x 250 380 H = REAR POSITION 2,5x 9,5x 250 180 H = REAR POSITION 135 5¼" 85x100mm 3¼x4¼" 0,25x 0,9x 250 380 H = REAR POSITION 0,9x 11,0x 250 180 H = REAR POSITION 105 4⅛" 65x90mm 2½x3½" 0,2x 0,7x 380 380 H = REAR POSITION 0,7x 4,0x 252 180 H = REAR POSITION 4,0x 14,0x 180 160 H = REAR POSITION 80 3⅛" 60x60mm 2¼x2¼" 3,8x 21,0x 180 130 H = REAR POSITION 60 2⅛" 40x40mm 1½"x1½" 5,0x 26,5x 160 130 H = REAR POSITION 50 2 24x36 35mm 6,7x 33,0x 160 130 H = REAR POSITION

Table of condenser combinations for the Durst Laborator 184.

Lens f = mm / inches Negative size
mm / inches Linear magnification
minimum maximum Condenser Combination +LAZUC0 181 Position of mirror lever Condenser position. 360/14 200x250mm 8x10" 2,5x 0,9x 382 380 H = REAR POSITION
V = FRONT POSITION 9,0x 21,0x 380 380 V = FRONT POSITION 300/12 200x 250mm 8x10"
180x240mm 6½x8½ 4,0x 5,3x 380 380 V = FRONT POSITION 5,3x 23,0x 380 380 V = FRONT POSITION 240 9 ½" 130x180mm 5x7" 5,0x 6,5x 380 250 H = REAR POSITION 6,5x 33,0x 380 252 H = REAR POSITION 210 8½" 130x180mm 5x7" 6,2x 33,0x 380 252 H = REAR POSITION 180 7⅛ 100x150mm 4¼X6½" 7,5x 43,0x 250 252 H = REAR POSITION 150 6 100x125mm 4x5" 9,5x 20,0x 250 180 H = REAR POSITION 20,0x 43,0x 252 180 H = REAR POSITION 135 5¼" 85x100mm 3¼x4¼" 11,0x 47,0x 250 180 H = REAR POSITION 105 4⅛" 65x90mm 2½x3½" 14,0x 67,0x 180 160 H = REAR POSITION 80 3⅛" 60x60mm 2¼x2¼" 21,0x 73,0x 180 130 H = REAR POSITION 60 2⅛" 40x40mm 1½"x1½" 23,0x 84,5x 180 130 H = REAR POSITION 50 2 24x36 35mm 33,0x 170,0x 160 130 H = REAR POSITION

On the left-hand side of the condenser head, when standing in front of the enlarger, there is a leaver. This lever manipulates the large mirror inside the condenser head; please make sure this lever is in the right position for the enlargement at hand.

When nothing else in mentioned the condensers is installed in the head with the curved sides facing each other.

When a point light lamp is used the condensers must be of the coated type.

Lesson 11: MANUAL FOR the DeVere CONDENSER SYSTEM, Available from DURST-PRO-USA, Inc.

MAXIMUM NEGATIVE SIZE RECOMMENDED LENSES CONDENSER COMBINATIONS 11x14" 480mm Rodagon, 300mm Rodenstock Geragon, 270mm Rodenstock Geragon. 4 elements, set #1 and set#2. 10x10", 8x10" and 18x24cm 480mm, 360, 300mm or 240mm 4 elements, set #1 and set#2 5x7", 13x18cm and 6x17cm 240mm, 210mm and 180mm 4 elements, set #1 and set#2
240mm supplementary element 4x5", 9x12cm, 6x12cm 210mm, 180mm and 150mm 4 elements, set #1 and set#2
180mm supplementary element 6x9cm and 6x7cm 150mm, 135mm and 105mm 4 elements, set #1 and set#2
180mm supplementary element and thin spacer in negative holder. 6x6, 4.5x6 and 4x4cm 105, 90mm and 80mm. 4 elements, set #1 and set#2
180mm supplementary element and thick spacer in negative holder. 35mm 60mm lenses 4 elements, set #1 and set#2
180mm supplementary element
one thick and one thin spacer in negative holder

Please notice: When using a condenser system the critical components are the enlarging lens and the condenser lenses. How those two items are combined determine the size of the illuminated area and the lamp position. The size of the negative has no influence on the result. What do I mean? What I mean to say is that regardless of the negative size the enlarging lens HAS to be used with the right combination of condensers. And I am saying that any size negative can be used with any correct combination of enlarging lens and condenser lens. Example #1, a "small crop" crop of from an 10x10" negative can be printed with any focal length lens having a circle of coverage large enough to cover the diagonal of the crop as long as the correct condenser combination for that particular lens is used. Example #2, a 35mm lens can be printed with any lens even a 480mm as long as the correct condenser combination for that particular lens is used. And of course the lens has to have a circle of coverage large enough to cover the negative.

This situation is ONLY limited by physical limitations of the equipment in use.

DeVere Condenser Light source adjustments:

Three adjustments are provided for centering the lamp on the optical axis. Two of the adjusting knobs are on the underside of the lamp house and one on the lower right-hand side of the lamp house. The larger of the two knobs on the underside adjusts the lamp in the vertical plane and the small knob, to the right of the large knob, imparts a rotational movement whereby the lamp filament can be squared with the aperture. The adjusting knob on the right-hand side provides lateral movement of the lamp at right angles to the optical axis.

  • To adjust proceed as follows:
  • Remove the negative holder from the machine and fit an 8xl0" (203mm x 254mm) frame. Install a negative, any negative.
  • See that the masking leaves are well clear of the 8xl0" aperture. The 2 hand wheels on the left-hand side of the machine can adjust the position of the masking blades. Some machines delivered by DURST-PRO-USA, Inc. have been retrofitted with the more advanced Durst negative holder. When this modification is made the masking blades has been removed to make space for the thicker negative holder.
  • Adjust the negative carrier rise and fall hand wheel until the scale at the right-hand side of the negative stage is at zero setting. This centralizes the negative carrier in the vertical plane.
  • Insert the negative holder in the negative stage until the ends are flush with the negative stage casting. This ensures the negative carrier is centralized in the horizontal plane.
  • Install a 360mm focal length lens to a on the lens stage. Set the lens to a wide aperture. Switch on the Condenser light.
  • (DeVere use a bayonet type fitting for their lens boards, high end machines delivered by DURST-PRO-USA, Inc have been retrofitted with a Durst lens board adapter.)
  • Release the negative stage locking lever, the lens stage drive and the condenser housing drive. Make sure that the negative stage and the condenser housing is properly connected.
  • Adjust the positions of the negative and lens stages on the optical bench to give approximate size and sharp focus. Now engage the negative stage locking lever, the lens stage drive and the condenser house drive in order to maintain sharp focus at the given size. REMOVE THE NEGATIVE!.
  • Release the lamp house runner locking lever and move the unit along it's expandable track.. It will be seen that the image, on the baseboard, appears to be of a circular nature with a dark fringe. Find the position where the illumination appears fairly even. Lock the lamp house runner in this position and stop the lens aperture diaphragm down until a white circle with a blue surround will become apparent. It is likely that this circle will not be in the centre of the projected image. Using the three adjustments described at the beginning of this paragraph. Adjust the position of the lamp until it is perfectly centered in relation to the negative and optical systems It is possible that there will be a slight cut-off of the projected image.
  • If the cut-off is the same at the four edges of the image adjust the position of the lamp-house on it's track until a perfectly clean, white illuminated area is obtained.
  • If the cut-off is not the same at the four edges it is possible that the position of the condenser lens mounts need slight adjustment. Ease the Condenser mount adjusting/locating screw under the lamp house bellows to adjust in a rotating movement. Use the 2 adjusting screws on the right-hand side of the condenser housing to move the condenser mount assemblies in small increments from right to left. If it is necessary to move the mounts in the opposite direction, ease the two screws slightly, open the housing door on the opposite side and move the mounts by hand Repeat adjustments until the required positions are obtained Finally ensure that the Condenser mount adjusting/locating screw under the bellows is firmly tightened.


The table of recommended lens and condenser combinations shows that the standard 4-element condenser assembly will cover negative format sizes from 11xl4" down to 10x10".

For smaller negative formats the use of supplementary lenses is recommended. Two supplementary (condenser) lenses with diameters off 180mm and 240mm are available for this purpose.

The supplementary lenses are mounted on metal plates which locate in the recess in the negative stage in the same manner as the loose plate used when the standard condenser assembly only is being used.

The mounting plate should be inserted in the recess with the convex surface of the supplementary lens facing the condenser housing When the condenser/lamp-house assembly is moved into its operating position and secured to the negative stage.

The convex surface of the supplementary lens fits neatly within the concave surface of the foremost element of the standard 4-element assembly.

For negative sizes 6x9cm and below, in addition to the use of supplementary lenses it will be necessary to position the negative further away from the condenser system in order to keep it in the most intense part of the light beam.

This is achieved by the use of either a circular negative holder adapter for the smaller formats, available in a 30mm and 60mm version, or by the use of a spacer between the negative stage and the condenser housing. Both types are available from DURST-PRO-USA, Inc.

Jens J. Jensen
World Images Inc.
May 30, 2002.

Lesson 12: Is it really "either or"? Is it really either digital or optical photography?

The thoughts in this paper are not all unique thoughts of my own; many ideas and thoughts have been created and defined in discussions with colleges and friends…the paper is strictly a Fine Art Photographer's view.

Had I decided to look at it from a commercial photographer's view or from a commercial lab's view, the thoughts would have been the same, but all the drawbacks would have been justified by speed and competition.

A commercial photograph of a product, or a feeling conveying a product, is meant to last only for a very brief moment. The original purpose of a commercial shoot is rarely to produce a photographic print for display or to reproduce the image on photographic paper as a historic or emotional document, a commercial photograph is simply meant to promote a sale or decorate packaging. For that purpose the Digital medium is perfect. It is fast and cost effective. Based on email directives from an art director, a photographer can produce an image in the morning, transfer it by phone to a commercial lab, which in turn will output it on a piece of vinyl that is hung in the subway later that same afternoon. Or the file can be transferred to a commercial printer and be on thousands of boxes the same day. Digital is perfect for that type of production, and it definitely takes skill and creativity to master the medium.

When I first saw Mamiya's add campaign with the New York ballet dancers, caught mid air, I was struck with awe. I knew it must have been extremely hard to have not only performed the jumps but also to catch it on film. When I see those images today, and similar images like someone snowboarding out an airplane, I no longer pay attention.

My instant reaction is; "Well done Photoshop?

I do not know about you - but the only thing I can truly admire and respect is human accomplishments.

Since everyone can twist and turn the reality in Photoshop, photographic documentation of accomplishments no longer have the same value.

Just as my respect for diamonds dwindled when I learned that the only way to distinguish cheap Russian factory made diamonds from natural diamonds is by engraving natural diamonds with a number.

Let us be frank about it. Digital photography was not invented to make photography better, to make photography less expensive or even a more accessible ?it may be that it will obtain those qualities in a distant future ?but for now it was "invented?nbsp; by a group of companies like Samsung, Intel, Epson and Hewlett Packard in order to take over market share from more "mechanical?nbsp; companies like Polaroid, Kodak, Durst Italy, Agfa and Gretag, who are struggling to adapt to the new challenges. Or simply, Digital was "invented? to make money for the producers of the digital products. And of course it was a byproduct of the ongoing digital evolution which is fueled by cost cutting and profit increasing purposes ?I can guarantee you it is fulfilling that purpose for the patent holders.

Whatever may be fueling the Digital Revolution ?YOU, the consumer of the products, are paying for it ?do not for one second think differently. Digital was not "invented?to save you money.

Let us address another issue of digital ?longevity or permanency.

The guaranteed life span of a CD-ROM is only 20 years. The plastic substrate on which the light sensitive surface is applied is not guaranteed to last longer than maximum 20 years, unless kept under some very certain and very expensive circumstances. Do you remember what happened to the first resin coated photo papers? The prints made on those papers disintegrated after 3-4 years.

Museums, The State and individual photographers are already experiencing loss of data due to obsolete recording devices.

Sony is working on an entirely new CD-ROM format. It is said to be able to hold at least 4 Gigabytes on the same space that holds 600MB today. This new format is said to replace all other formats, CR-ROM, DVD, etc. How many formats have we already seen, 4? floppy, 3?floppy, the current floppy, ZIP, DIP and you mention it. My first Laptop is only 8 years old and is no longer supported by anyone, the data on it is completely lost unless I am willing to spend ,500.00 on having the 400MB hard disk transferred to a CD-ROM ?a job that can only be carried out by some experts in Texas.

And then, the CD-Rom issue is probably the least problematic issue. Digital hardware and software generally has a life span of less than five years. None of my printers have lasted me more than 3 years. Compare that to an optical enlarger from Durst; The Laborator 138S was introduced in 1948 and is still producing prints as good or better than any digital print. Maintenance and upgrades in the entire period of 54 years has been limited to new bellows, new bulbs and a set of new lenses.

Microsoft is now working on an entirely new security system for PC's and is also predicting that the PC is going to be replaced by a "multi-task-cable-access-keyboard?allowing the user to access entertainment and remote data storage simultaneously. The great future predicts that all programming and data storage will take place on remote servers ?fee based of course.

Hundreds if not thousands of companies are investing billions of dollars in research and development of new software and new hardware.

For each hour YOU spend on getting to know your existing programs hundreds of programmers are spending hundreds of hours on improving and combining those same programs. Adobe has 3,500 employees ?Samsung and Epson 63,000 - what do you think they are doing?

The time and effort I have put into being a skilled optical photographer and printer is something I want to be able to keep building on. I feel safe with my optical enlarger, I know it is technology that no one can deem obsolete and therefore force me to give it up or to spend thousands of hours and dollars on Digital technology that I have no control over.

I want to grow. I want to be able to use the next 20 years to learn more and not to learn new over and over.

Digital is at the moment a big "Black Hole?sucking in artistic energy and resources.

If you sit down and make a more detailed cost analysis you will realize that the cost of a package of 20 sheets, of 8x10?art paper, suited to produce a picture of the same quality as a regular optically produced photograph, is around .00. The ink used to produce those 20 prints will on average cost at least another .00 making the total materials cost around .00.

The material cost for 20 Color prints produced optically on RA4 Color paper is approx. .00 ?25% of the cost of inkjet prints.
The material cost for 20 Color prints on ILFOCHROME Color paper is approx. .00 ?only 20% more than digital inkjet.
The material cost for 20 prints on BW RC paper is approx. .00 ?half of the digital cost.
The material cost for 20 prints on BW Fiber base paper is approx. .00 ?a bit more than half the digital inkjet cost.

Digital is often marketed as being "more environmentally safe?than optical photography, which is being portrayed as "chemically-dirty? I am not quite sure if I buy that explanation at the present time. The influence on the environment from the production of the digital devices, and getting rid of obsolete devices by the million of tons, sure is hard to compare to photo-chemicals that for most part contain only substances found in nature.

One thing is for sure; Digital photography is on the evolutionary ladder, where optical photography was 150 years ago. Digital Photography is in its infancy.

If you add up the cost of the computer, the scanner and the printer(s) and take into consideration its lifespan, upgrades in the lifespan and certainly the production capacity in the lifespan, the cost of consumer quality digital equipment is approximately 3-5 times that of similar optical equipment (enlarger, processor/trays). When talking professional quality equipment digital is on average 10-12 times as expensive as optical equipment.

Now do not misunderstand me ?I think the digital revolution is great, I love it. Digital as such keep the commerce going, enriches the world and makes the world smaller and communication more efficient. Digital imaging has enabled us to view live images from Mars!!!!!

I ALSO love and believe in Optical Photography - I love it so much that I base my life and my career on Optical Photography.

I do not believe the hype - I do not believe that I have to switch FROM "Optical" TO "Digital" just because I am told that "Digital is the future". I do not believe that it is OPTICAL versus DIGITAL. I do not want to make a choice between the two. I believe that the two mediums is complementing each other and that they will co-exist in the future - side by side - just as color and BW does today.

Also, I do not want to jump on the Digital bandwagon because I cannot afford the ride. I do not have the time to keep up with 100.000 programmers. I want to invest my time and my feelings in a medium with a proven track record. One that gives me a chance to get to know it before it changes. I do not believe that the "Holy Grail" is change.

I believe that life is about feeling good about what you do. I believe that "feelings" are, if not more, then at least as important as being first and "hip".

Part of my interest in Photography is fueled by a chance to leave something behind for my children and their children, to document how "we?lived through photographic expression. Because I am concerned about preserving my hard work - my prints - my expressions - I cannot use Digital because the medium is driven by "corporate economy" and contains features over which I have no control.

What are you leaving behind? ? prints to be viewed or "bits?to be sent to Texas to be restored and translated?

Jens J Jensen,

Oregon, November 2002.
Updated June 2003.

Comment February 26, 2003.

Some time ago I had a very interesting discussion with a lab owner who called me to ask about our intentions for the future. George Peterson owns a photo-finishing lab, which is a lab receiving consumer films for printing, in Florida. George complained about the very low return on investments (ROI) in digital photo-finishing equipment and told me that some digital items had been made obsolete before they had returned 20% of the investment. He wanted to know if we could supply Durst printers, which he had heard had been "in business" for at least 20 years. He formulated the following very interesting thought:

He said; "I cannot understand how anyone can expect an average consumer to spend even 20 minutes downloading and manipulating digital images form Saturdays soccer match when they have a hard time waiting one hour for regular print services. An hour that can be spent shopping or doing something interesting. And the fact is that at present it will take at least 2-3 hours to digitally process 24 images on a home computer obtaining ONLY mediocre results compared to glossy 4x5 prints on Kodak or Fuji quality paper. I predict that the companies relying entirely on this new expectation to digital consumers will end up facing severe difficulties."

Well, it seems like his prediction was not far from the truth. Gretag, producer of digital photo finishing equipment, just went "Chapter 7". Visit their website and you will see that they had transformed their company to "digital" - entirely.....


On top of introducing a new high quality OPTICAL SCOTT GLASS we have taken the quality issue one step further by introducing ANTI REFLEX COATED glass. The coating is largely similar to the coating found on your camera lenses.

Did you know that glass is a super cooled liquid? It is in fact.

A normal windowpane will over time grow thicker at the bottom than it is at the top. The larger the window and the thicker the glass the more pronounced this effect will be. The weight of the glass it self will force the glass particles to slowly travel towards the center of the earth due to gravitational force!

Glass is a completely natural product produced by nature in a variety of colors and transparencies.

Window glass most often has a slight green cast to it, which indicates that it is a soda lime product.

Modern optics are produced with very advanced glass types. Hard-glass. Glass produced to be used in photographic optics are completely clear and color less. Some glass formulas are so refined that the producer keeps them secret.

Sheets of glass can be produced in two different manners. Sheets of glass can be produced by extrusion; The molten glass is rolled and gradually pressed flat to the desired thickness with rollers gradually applying more and more pressure to the initial molten glass rod.

Sheets of glass can also be cut from blocks of cold glass and polished into the desired thickness and tolerance.

Sheets of glass cut from a large block of glass and polished into the desired thickness is naturally much more dimensionally precise than their rolled counter parts.

In order to obtain the highest possible quality glass for Durst negative holders we are introducing an entirely new type glass.

We are introducing cut and polished SCOTT GLASS for Durst negative holders.

The exact same type SCOTT GLASS is also used for Schneider and Rodenstock lenses.

SCOTT GLASS is completely color less and thus will allow VC and Color Dichro light sources to be used to their maximum filter values. The old green glass absorbed almost 20CC Magenta filter value which prohibited obtaining maximum paper grade and also led to extended exposure times.

On top of introducing a new high quality OPTICAL SCOTT GLASS we have taken the quality issue one step further by introducing ANTI REFLEX COATED glass. The coating is largely similar to the coating found on your camera lenses.

We have discontinued the old type AN (Anti Newton) glass because it deteriorates sharpness considerably. The rate of deterioration is so considerable that Durst Auto Focus enlargers can not be programmed for correct focus using Anti Newton Glass.

The new AR glass will also suppress Newton rings. Also the trend is that Fine Art printers now are using a glass less mask on top of the negative and only glass at the bottom.


The NEW negative glass for Durst negative holders from 4x5?to 12x16?are made by German Schott Glass. Schott glass is also used for camera and enlarging lenses and as such we have made the highest possible quality of glass available for enlarging.

Schott Optical Glass is pure white and clear. It will allow transmission of light is the full spectrum from 370nm to above 700nm.

Clear Schott optical glass transmits more than 85% of the light reaching it. With single sided Anti Reflex coating the transmission is increased to 95%. With double sided AR coating the transmission is increased to 98%.

We offer both un-coated Schott negative glass as well as single sided and double sided AR coated glass for ALL Durst negative holders.

Transmission curve for Schott Optical Glass used by Jensen Optical for their negative glasses.
%T = Percentage transmission.

For Color Negative and BW:

For BW photography I recommend uncoated glass below the negative and single sided AR Coated glass on top of the negative. The coated side (Beveled side) facing the "glossy?side of the negative (Non emulsion side)

For Transparencies:

I recommend using single sided AR coated Schott glass both under and on top of the transparency when printing ILFOCHROME.

If you desire another 10% light transmission I can recommend Double sided AR coated glass.


Single sided AR coated glass will have the coating on the beveled side.

AR Coated Glass will also suppress Newton rings.

Coated and Un-coated Schott Glass will require less Magenta filtration due to it being absolutely clear in contrast to the old Soda-Lime type glass which have a distinct green color.

Schott Optical Glass will improve sharpness for both BW and Color negatives as well as transparencies.

AR (Anti Reflex Coating) Glass will also act as Anti Newton glass.

The AR Coating used on the Schott glass is STATE of the ART coating. It is a coating more advanced than even the Multi Coating you see on most camera lenses.

The AR-Coating on Schott Glass is almost invisible to the naked eye. If you get in doubt of which glass is coated and which glass is uncoated please make a test as follows:

Rub your finger on the outside of your nose to pick up a little bit of grease. Make a small finger-print in the corner of the glass you want to test. On the AR type glass you will see your finger print having a metallic shine. On un-coated glass you will just see a finger print. There is quite a difference.

The real advantage to the AR-Coated glass is the fact that it is invisible.

The main purpose of the AR-Coating is to increase sharpness and to increase light transmission.

I have tried to obtain a situation where the enlarging lens will see ONLY the negative or transparency it self and not a grey-green barrier in front of the negative (grey-green = Soda Lime Glass).

The difference between two pieces of the old type Soda-lime glass and two pieces of double sided AR Glass can amount to an increase of 2/3 of one f-stop light transmission ?that is almost one full f-stop gained ?and also an increase of up to 20% in resolution.

In short you will get more light and a sharper output.

Schott Optical Quality glass is also more robust than Soda Lime glass, which is softer.

However: I do recommend that you take care not to use abrasives when cleaning the glass.

After extensive testing and research I recommend the following procedure for cleaning;

Soak the glass to be cleaned in plain WINDEX for approx. 10 minutes. Use an absolute clean plastic tray of the type that is used for making prints ?make sure that NO chemicals have ever been in the tray.

Use a glass or metal rod to tilt the glass out of the WINDEX, grip it by the corners and dry it gently ONCE with a soft lint free cotton rag. One stroke with the rag rolled up in a tube shaped form long enough to cover the width of the glass. Use the cotton gloves supplied with the glass to handle it.

Do not cover the glass more than once when wiping it ?it can cause streaks ?the best result is obtained when the glass is damp after having been dried once allowing the Windex to evaporate evenly.

You do not have to threat the AR Coated glass any differently than you would un-coated glass.


Do not use any kind of paper, metal objects or abrasive sponges to rub or scrub the glass ?it will for sure scratch the glass even though it will not be visible to the naked eye.

If you want to use tape on the glass feel free to do so ?I assume you then also use tape on the front element of your shooting lens!

If you use tape anyway and want to remove any tape residue later you can do so using de-natured alcohol, acetone or Methol-Etyl-Keatone (MEK). It will not damage the glass or the AR Coating.

DO NOT USE ANY kinds of acids on this glass.


Always keep an old negative in your negative holder when it is not being used. This will prevent scratches to the glass caused by small dust and dirt particles. When two pieces of glass is in contact, without anything in between, it does not take much to create a scratch.



First take a look at the spectrum for visible light. That is the colored area, curve marked "A"

Then take a look at Curve "B", which is an average BW emulsion. Those two curves fit pretty well together.

Please notice, for later, that the BW emulsion is a lot more sensitive in the 700nm area than the human eye. As a matter of fact that is the area where the BW emulsion has its sensitivity peak.

Multi Contrast papers(MC papers) has two emulsions, one on top of the other. One is sensitive to one part of the spectrum, the other sensitive to the part of the spectrum which the first is not sensitive to. There is some overlapping. Together the two emulsions are sensitive to the area indicated with Curve "B" above.
When printing on MC paper the spectrum of the printing lamp is changed by inserting Multi Grade Filters into the light beam. Or by dialing in the right values of Yellow and Magenta on a color head. By altering the spectrum of the light you you modify the spectrum of the printing light to create a new spectrum. This new spectrum will determine how much light will reach each of the two emulsions on the MC paper. The degree to which each of the two emulsions are exposed (receiving light) will determine the grade delivered by the paper.

Example #1: Grade 00 is almost entirely yellow light, as you will see above that is the spectrum from approx. 560 to 600 nm. (A pure Yellow filter cuts off all light emission below 520nm)

Example #2: Grade 4 is a mixture of Yellow filtration and Magenta, which as you know is reddish light. Red light, and Magenta light is all above 600nm. (A pure Magenta filter cuts away all light emission between 500 and 610nm, and lets through light emission BELOW 500nm and ABOVE 600nm, Magenta is a mixture of Blue and Red light.

Now in order to be able to create light in the area 550nm to 700nm it is necessary that the lamp in the enlarger emits that spectrum in the first place, before the MC filters are inserted. If the lamp do not emit light in that area it is not possible to use the filters to create it, as it is not existing in the first place. Sort of basic but necessary to understand.

Now take a look at the spectral emission by a NEON lamp which is the type of lamp used in conventional COLD LIGHT heads.

As you will see almost all the emission from the NEON TUBE is in the area before 550nm. As a matter of fact the emission peaks around 410nm.and there is hardly any emission in the red area above 600nm.

Finally take a look at the light emission produced by our DULAMP-1200-TOP:

AS you will see the emission is almost all in the 350nm to 1200nm. Therefore this lamp is ideally suited for modern BW papers.

Do you remember, from the beginning of this paper, that the BW emulsion is a lot more sensitive in the 700nm area than the human eye. As a matter of fact that is the area where the BW emulsion has its sensitivity peak. If you look at the DULAMP-1200-TOP you will see that is exactly where it's emission peaks.

Those technical facts were the driving force behind developing the new LAMP-KIT, of course the OPAL bulb being discontinued also played a role....

Article authored by Jens J Jensen.

Source: Kodak, Phillips, Osram and W.W.H.Clarke.