Back To The Future by Andy Cross

            During the 90’s when digital capture seemed to be really making photography redundant, and manufacturers began pulling the pin on making many films and papers that had been around for years, I did a mild panic. I went out and bought another deep freezer to compliment the one I already had and stuffed it full of materials as well.

            One of the materials I needed if I were to continue making dye transfer and tri-colour carbon prints was colour transparency film. Fuji seemed to be the only manufacturer still in the game and if they stopped then I would need to be able to make colour separations by another means. (NB. Kodak Ektachrome is being made again by Kodak Alaris ) 

            The materials for making these types of colour assembly prints from colour negatives are no longer in existence and an inter-positive needs to be made first. In short for making either type of colour print the necessary contrast reduction and colour corrective silver masks are made first. The combined masks and transparency are then contact printed onto three separate sheets of a suitable panchromatic B&W film. Each of the three exposures are made through the required red, green and blue filters.

            In the case of carbon printing, which is a contact printing process, the combined masks and transparency is enlarged onto the same type of B&W film using red, green and blue light. In either case the first order result , that is the in camera original, begins with a colour transparency. This is where the colour information is recorded. If I was unable to source colour transparency film then making non fugitive colour prints would become a lot more difficult albeit still doable.

            The solution would be to adopt the same process that was used before the tri-pack colour films we use today had been invented. It involves making three colour separation negatives directly from the subject. The most efficient way of achieving this is to use a one shot colour separation camera. These cameras as the name suggests records three images on three separate sheets of panchromatic B&W film through each primary coloured filter simultaneously.  

            Although these cameras still exist in various states of condition finding one that was still operational or very nearly so proved to be more difficult than I anticipated. There were several makes and models made over the years. Brand names like Bermpohl , Sheppard, Curtis, Lerochrome and Devin. There were also a spattering of Gandolfi, Deardorf and De-golden Bausch cameras. The last three are rare because not many were made.

            Having roamed the world on the web and finding only expensive junk I almost abandoned the idea until a friend of mine mentioned there was a guy in Stanhope here in Queensland who had such a camera in his collection. I followed up on this and sure enough it was a Bermpohl and he was willing to sell it to me. This camera was in the best condition I had seen. The bellows was in good condition, it was still light tight and worked. 

            The schematic of how the camera works is shown in Fig #1. The lens brings the image into focus which passes through a beam splitter. This consists of three semi-silvered mirrors. Each image then passes through a narrow band width colour separation filter positioned between the incoming image and film. 

            The work needed to make it operational with modern emulsions I thought would be minimal. This didn’t prove to be correct. One of the issues was although the bellows was still light tight it wasn’t lined with anything. The leather was just as shiny on the inside as it was the outside. Quite a lot of bellows flare is produced. This wasn’t an issue when the glass plates of day, around 8 ISO, were being used. But 400 ISO T-Max was just being fogged to non-image forming light. 

            The lens, an un-coated Hugo Meyer 215mm f4 plasmat, was in good condition but unsuited for making colour separations on modern emulsions. The hole in the lens board didn’t match any of the copal shutters attached to my collection of Rodenstock Apo’s so another lens board was going to have to be made. I hadn’t expected this. 

            The film holders were another issue. They leaked light like a sieve. They were all metal and needed to be reworked extensively to make them light tight again. Finding someone capable of doing this work was difficult. The baked enamel coating would also need to be redone as they looked battered. This proved to be the most costly part of the process thus far.

            In the days when this camera was made an enamel finish meant just that. Glass melted over metal. Not baked enamel paint as we expect today. Doing this for 12 film holders was more than I was prepared to pay. I would just keep the holders and get new nylon plastic ones made. This gave me the option of installing a registration system into the film holders foregoing the necessity to post register the separations after they were processed. A luxury not available at the time the camera was manufactured.

            After dismantling the camera I found the semi-silvered mirrors to be in need of re-coating. This was a far easier option than if the camera used pellicles as many of them do. The resilvering was done in Japan using vapor coated aluminium. Unlike silver this will not degrade and blacked over time. Realigning the mirrors was a tedious process but done with a laser alignment tool meant the mirrors were probably better aligned this time than they were when it was new.

             A modern bellows to fit this camera was another matter. There is a company in the UK who specializes in making bellows for all types of equipment. After sending them detailed photographs of how it fitted the camera and accurate micrometer measurements taken, I eventually obtained a new matt black nylon bellows. 

            Getting a matching wooden lens board made from teak seemed unnecessary as the bellows was completely out of character with the rest of the camera any way. A pair of black aluminium lens boards for two different shutters that fitted a Canham was the easiest alternative.  The reason I didn’t just modify the existing camera parts was because of what an antiques appraiser who specialized in cameras told me.

            I would devalue the camera a lot if I couldn’t return it to concourse condition. I was urged to only replace parts for use then be able to refit the original parts. The camera with all the original film holders, lens, tripod, carry case and instruction manual was worth a lot more than I paid for it. 

            Almost twelve months passed before I had assembled all the parts to bring this camera into the 21^st century. The time had come to calibrate it and make some colour separation negatives. This is where things started to go haywire. 

            The calibrating procedure for making colour separations from a colour transparency  is basically the same for any of the colour assembly processes. The only difference here is that the separations are made directly from the subject being photographed. This procedure is something I have done many times for both dye transfer and carbon printing. Things seemed to be on track and I soon had a balanced set of colour separations that matched in density range and contrast.  

The calibration subject was a colour patch chart and grey scale. See Fig #2. In dye transfer these separations are enlarged onto a special type of film called matrix film. Once processed the matrices as they are called are soaked in dye complimentary to the colours of the filters the separation negatives were made with. The prints are made by rolling these matts into contact with a specially prepared gelatin paper. The dye literally transfers from the matrix to the paper and after all three transfers are completed the full colour image is re-created.

            When the first test print was made the dyes tracked to grey very well and the saturated colours looked fine also but everything else was out of balance. I couldn’t believe my eyes. How could grey reproduce as grey and have such an imbalance everywhere else? See Fig #3.

After a week of investigation, I eventually spoke to the right person who asked me what kind of filters were fitted to the camera. I replied a set of density staggered daylight balanced colour separation filters. How do you know they are daylight balanced filters was my friends reply?

            My response was “Well back when the camera was made they didn’t have electronic flash, quartz halogen or photoflood lamps. They used daylight it was the only light source bright enough”. The reply I received was Ah but they did have magnesium flash powder as well. My jaw dropped because the sort of result I had was consistent with using a light source of a discontinuous spectrum. Magnesium flash does in fact produce a discontinuous spectrum.

            A bit like shooting a colour film under regular fluorescent lights. The light may look white to the human eye but it has large gaps in the spectrum where certain wavelengths are missing. The colour rendering index or (CRI) is low.  After examining the filters, I could not see any identifying marks. So the correct status mode was selected on the densitometer and some readings taken. Sure enough the filters absorption and transmission peaks matched those needed for flash powder.

            At this point the whole project hung in the balance. Where was I going to find a set of staggered daylight balanced colour separation filters of the correct size and density to fit a Bermpohl. Having worked in the optical industry for 26 years meant I still had a lot of contacts to try. But I struck out. Finally I had to bite the bullet and make a call to either Andover Optical in the USA or Edmund Optics in Singapore to see if they could help. 

            To my amazement the guy at Andover said sure they are a stock item we can supply them and glaze them to any size from the blanks. You have to hand it to the Americans if you have the money you can get anything over there.

            With the filters sorted I conducted another series of calibration tests. This time I was expecting everything to work as it was supposed to. To my amazement things had improved but the colour balance was still off.  See fig #4 I started backtracking to find out what I did incorrectly. Couldn’t work out where my blunder was. A few emails back and forth to other people who have restored and used a one shot camera and I had my answer.

 I forgot to make the colour corrective silver masks. When the separations are made from a colour transparency you have to make contrast reduction masks in addition to colour corrective masks. From the combined transparency and masks the colour separation negatives are made. The masks are necessary because colour transparencies simply have to great a density range to reproduce on paper. Furthermore the colour space of the dyes in the transparency do not match the colour space of the dyes available for printing. 

Similarly there has never been a B&W film that sees the colours of the world as humans would if we saw the world in tones of grey. Essentially I had to mask out the offending colours recorded by the T-Max 400. This is fine when the original colour transparency has colour in it to absorb with filters. Separations made directly from the subject are just B&W negatives which contain no coloured dye deposits.

             More emails and phone calls to people more knowledgeable than myself in the USA and I had my answer. Integral colour masking was the answer. What I had to do was replicate the effects of that orange-brown integral colour mask seen in colour negatives. I don’t know why I thought I wouldn’t have to make colour corrections but I needed to learn a whole new set of masking skills. Three months and many tests later I managed to beat the colour separations into submission. The technique of integral colour masking a of set of separation negatives is very complicated. So I have not detailed any of this. 

 It was time to try it out on a subject. I set up a still life which was to be another in the series of unrelated objects. What prompted me to do this series is perhaps a title for another article. The colour separations were processed. The numbers looked correct and a set of matrices were made dyed up and rolled out. To date I have made two dye transfer prints from negatives recorded by the Bermpohl. Fig 5 & 6

Although it is difficult to show the differences on the web between dye prints made from the one shot camera and those made from a colour transparency there is one thing I have noticed. The tonal separation in the shadows from the one shot camera is better than images from a colour transparency. I have also messed around with the camera by removing the filters from two of the film planes and  recorded a B&W negative, colour negative and colour transparency in a single exposure.

            So there you have it colour photography without colour film. Was it worth all the trouble. Yes I would still do it again. Because I learned a lot from the project, fine tuned my skills  and learned new ones. It has also given me some insurance against some bureaucrat telling me I can’t have colour film any more. As additional insurance I have also set up my film recorder to make colour separations from the Phase One medium format capture back. But that’s another story.

A   Description   of   Some   Terms

Dye Transfer Printing. www.dogfordstudios.com/dye-transfer-process  This link will allow you to see what is involved in making a dye transfer print.

Tri-color Carbon Printing. www.alternativephotography.com/the-carbon-transfer-process This link will allow you to see the basics of making a colour carbon transfer print.

A staggered set of colour separation filters. Panchromatic films are not equally sensitive to all the colours of the visible electromagnetic spectrum. Most of them are more sensitive to blue, indigo and violet light. Less sensitive to red, orange and yellow and even less sensitive to green. To compensate for this the densities of the filters used in a one shot colour camera are less dense for the green and red. The user then fine tunes the final exposure by introducing neutral density filters as well.

Silver masks. Are records of a fault in the original made in the opposite sense. They are made by contact printing the original onto a panchromatic film for the correct exposure and developing time. They are usually made unsharp in order to maintain better registration and avoid diffraction lines. Kodak made a film called pan masking film specifically for this process. It was actually Panatomic X without the anti- halation backing on it. Other materials can be adopted now the masking film is no longer made. I have also written a  book ( PDF format ) on masking techniques for the analogue and digital processes. 

Narrow Band Width Colour separation filters are very dense red, green and blue filters that don’t even allow all the red, green or blue wavelengths pass through them. Matching their transmission peaks to the sensitivity peaks of your chosen film is one of the requirements for making good colour separation negatives.

Colour separation negatives. Where the colours of an image or subject are split into tones of grey across three pieces of film. A digital equivalent is found in Photoshop in the channels palette. The red channel represents what the subject would look like if it had been recorded on a panchromatic B&W film with a red filter attached to the camera lens. The green and blue channel with a green and blue filter attached. 

Fugitive Colour.  Fugitive is a word used by image conservationists to describe materials that will fade, change colour or migrate even when stored under the most suitable conditions. All organic dyes and pigments used in photography, inkjet and lithographic printing are considered fugitive. Dyes used in dye transfer printing are fugitive but when combined with a metal mordant in the paper a new insoluble compound is formed. These compounds are called lakes and meet the image conservationists standards to be labeled non-fugitive. The pigments used in carbon prints should be of the inorganic type. Sadly some printers use organic pigments. Those made with inorganic pigments are considered to be non-fugitive.

Integral Colour Mask . The most commonly seen integral colour mask is found in C-41 colour negatives. Even unexposed colour negative films will display an orange/brown colour in the base fog. This is an absorption filter that helps filter out the arrastres associated with the image forming dyes in the negative. These help in the accuracy of the colour reproduction. Making integral colour correcting masks for a set of colour separation negatives which contain no dye deposits is a complex process very few people will ever have to master.

Arrastre A Spanish word meaning to get dragged along behind. A colour arrastre in photography is a contaminating colour that gets dragged along by a filter or other dye affecting the colour fidelity. The arrastre most common to cyan dyes and pigments is that they are too blue and not green enough. They also  reflect some red light. The magenta’s are too red and not blue enough. They also reflect some green. Yellows are spectrally not too bad but they are simply not dense enough to absorb enough blue light or anything else.