Color Enlargement Questions

Discussion in 'Film and Processing' started by scottroberts, Feb 23, 2018.

  1. Hi- I am starting to get into the nuts and bolts of film photography, and looking to start developing and printing my own color photos... While large format B&W will be a main part of the effort, I am also looking into developing my own 35mm stuff as well. I have been over the C-41 process pretty thoroughly, and think I have a reasonable starter's handle on the process. But i can't find the info I want regarding the actual process of enlarging and printing I am about to attempt.

    The equipment I am planning to use is older- it was my late father's equipment, so I have a bit of an attachment to it. Most specifically, I am trying to figure out how to enlarge and make color prints with an Omega D-II with the color head.

    I know there is a space for inserting color gels in the color head. My question is this- Is the paper exposed three times- once for each gel, with a changeover time between each? This is what I am imagining: That I will need a red, green, and blue gel set, and will have to expose, swap and expose each of the three to get the color to print...

    Could someone give me a short primer on the operation?


  2. You certainly could use the process you describe. But in my opinion I think it would be much easier to obtain an Omega dichroic color head to fit your enlarger.
  3. Hi, I don't know your specific color head, but the most common routine is that they are set up for a single exposure, only. The color head would have three dials, labeled cyan, magenta, and yellow. These are called "subtractive" filters fwiw, and can all be used in the light path simultaneously without affecting each other.

    If you consider "white" light to be made up of equal parts of red, green, and blue light, each subtractive filter blocks only one color - for example, a yellow filter blocks blue light, but has no effect on the red and green (the combined red and green light look yellow to us).

    These filters are set up to have a variable effect, from zero (no effect) up to a pretty strong absorbance. In early color heads these would be long gradient filters, starting from nearly clear on one end to a strong color on the other; turning the dial changes the section of the filter which is in the light path. In later color heads they used so-called dichroic filters which are very "pure" filters, and are essentially immune to fading. The dichroic filter, an "all or nothing" filter is pushed a different distance into the light path, so the result is some proportion of filtered vs unfiltered light. But to the user, the effect is the same with either style color head - you just dial in a certain filter strength for each color.

    Anyway, the process is to dial in your roughly average filter set and expose a test print for so many seconds. You develop the test print, then decide what you need to do to fix it (this is called "color correcting" your print). You change the exposure time to make it lighter or darker (more exposure makes it darker), and if, for example, it is too yellow, you dial in more yellow on the color head. Keep repeating the process, gradually getting better, until you are satisfied with the print.

    All of the color prints today use what they call the RA-4 process; you can find online information about this. There is a "room temperature" application of this in some cases, where you can develop in a tray (near darkness is required) based on a time/temperature table.

    Best of luck with your enlarging. Be aware that color correcting is a skill that you learn, and it can be pretty frustrating for a beginner.
  4. Hi Bill- The color head I have is actually a "first generation" style: It does not have the three colors already in place: it actually has a simple slot to slip in a holder with any of the three colors to filter! The Chromega and others developed after this one... I may pick up a used color enlarger if this proves too labor intensive... The enlarger I have was used by my dad for decades for B&W large format, so it will always have a use... But I want to get into color film as well, and wanted to see how to do it with the old style enlarger...

  5. Color photo paper has a complex structure but you should think of it as three emulsions coated on a paper base. One emulsion is sensitive to red, one to green and one to blue light. Contained in each emulsion is an incomplete dye. The red layer contains an incomplete cyan dye. Cyan is a blue + green color. The green layer contains an incomplete magenta dye. Magenta is red +blue. The blue layer contains an incomplete yellow dye. This incomplete dye state is called leuco from the Greek for hidden.

    The developer contains the missing ingredient. This is a single ingredient that can cause all three leuco dyes to blossom, it if complexes. This happens if during development. The missing ingredient unites in proportion to the amount of silver liberated. In other words, a black and white image forms, dye accrues in proportion with the silver.

    The paper must be properly exposed if the resulting image is to have good color balance. The trick is to independently correctly expose each layer. There are two common methods to accomplish. 1. Additive – Strong red, green and blue filters are procured. These are inserted into the enlarger. Three sequential exposures are made, one for each of these light primary filters. Good color balance is dependent on proper control of each exposure. Generally, exposure is control is performed by adjusting the time of the exposure for each. This method called additive color printing is the most difficult. While not impossible to preform, you will likely waste tons of paper to achieve your first good print.

    The second method is called subtractive printing. You must procure a set of magenta & yellow filters. The set will contain the following strengths for each. The following are density values – 0.025 – 0.05 – 0.10 – 0.20 – 0.40 – 0.80. I would not hurt if you added a set of red filters.

    After composing and focusing the enlarger, add to the filter holder 0.40 magenta and 0.80 yellow. Set the aperture of the enlarger in the center of its range. Make a test strip 5 – 8 – 10 -15 – 20 – 30 seconds. Develop the test strip and examine for best density. Now look at the color balance of this patch.

    If too yellow add more yellow to the filter pack Work in units of small = .05 – medium = .10 – large = .20

    If too magenta add more magenta to the filter pack work in S – M – L units.

    If too cyan remove in equal amounts yellow and magenta work in S – M – L units.

    If too red remove magenta and yellow in equal amounts work in S – M – L units. .

    If too green remove magenta work in S – M – L units.

    If too blue remove yellow work in S – M – L units.

    Email me if you need more help – once I was an instructor subject color print and process
    casey_c, bgelfand and Sandy Vongries like this.
  6. Ok, well it is still perfectly doable to use this setup, although a more recent colorhead is much more convenient.

    What you would want to get is an assortment of filters in the right size - these are probably gonna be pretty expensive to get new, but maybe you'll find an assortment of used filters for cheap?

    Provided that they don't go into the actual imaging path, look for CP (color printing) filters (gelatin CC filters have the same values but are much more expensive). You would want a set of cyan, magenta, and yellow filters that can be stacked up in any set of values, in 02 cc increments. Typically you would only need a small quantity of cyan, but want to go well over 100 in the yellow and magenta. If you get filter units of, say, 02, 05, 10, 20, and maybe several 40s, you can build up just about any number you need. For example, to get 37 cc, you could use 20+10+5+2. There is an additional downside - each added filter surface looses a little light to reflection, so if you made a test with the 37 cc filter pack above, but decide you need to go up to 40cc, you would remove the 4-filter pack, and replace it with a single 40cc; this would actually let a little more light through so might also need a slight exposure correction. So it might be preferable to simply have added an extra 2cc filter, if you had same.

    Anyway, it's definitely doable, although a dichroic color head is far more convenient. In my earlier years I spent a lot of time in a large lab using the manual filter methodology. What we did was to use a pair of filter packs. The "master" pack was used to get all of the printers to roughly match each other, then relatively small corrections were used in a "working pack" for specific negatives or rolls. This also reduces the liklihood of an error in adding up the correct filters (you can make dumb mistakes when you do it enough).

    Alan has certainly been "around the block," so to speak, in the world of photofinishing, so don't take him lightly. Personally, when it comes to color correcting, I adopted a rule long time ago - I call it "always do the wrong thing." After this, I virtually never made errors in figuring out the necessary filter changes. Basically, whatever color issue the test print has, you do what would "seem to" make it worse. For example, print is too yellow? Ok, it seems like the "wrong thing" to add even more yellow to filter pack, but that IS the proper correction.

    How about if print is too blue? Well, it seems like the wrong thing is to add blue to the filter pack, and that WOULD BE the proper correction IF we used blue filters. But since we normally work with subtractive filters, we don't use blue. So we ask, what is the equivalent to adding blue; it is to remove yellow from the filter pack, and again, this is the proper correction. Now, to figure what are equivalent corrections, we can draw a set of three overlapping circles, red, green, and blue, with the overlapping sections labeled as cyan, magenta and yellow. In my example, where you want to add blue (which we don't use), you find blue on the circle, then find that yellow is directly opposite to it. This shows that yellow is like an "opposite" color, actually called "complementary," meaning that adding blue is equivalent to subtracting yellow. Anyway, if you can construct the color wheel on the fly, then "always do the wrong thing," you don't need to keep the color correcting list that Alan has supplied. Just a different approach to getting the same answer.
  7. Vincent Peri

    Vincent Peri Metairie, LA

    I tried color printing back around 1976 or so. It really was too frustrating, so I just did B&W afterwards, until around 1978 or so, when I tried Cibachrome. Loved the results, but the chemicals were more toxic than I liked, so I quit that too.

    Hmm... black & white
  8. You need a set of CP (Colour Printing) filters at minimum. These come, or came, in sets of 2, 3 or 4 inch square 'gels'.

    There are 3 colours of filter, Cyan, Yellow and Magenta in a set, usually in densities varying from 2.5 to 50. (The actual density values are 100 times less than this, but those are the marked values)

    The filters are stacked together in the filter drawer of the enlarger to correct the colour. Only two colours of filter are used together - usually Yellow and Magenta - Cyan filtering is rarely needed.

    Colour printing paper comes in batches with a base correction recommendation. E.g. M 055, Y 045, C 000. These are the cumulative densities of the filter stack. For this correction you'd need 50M + 05M + 40Y + 05Y filters in the stack - a total of 4 filters.

    The base filter stack nearly always needs some adjustment to give correct colour.

    I'm not sure how easy it is to get CP filters these days; and they don't give the best quality of print. A dichroic head is definitely easier to use and gives better results.

    Processing RA colour paper needs tight process control to give decent results as well. You might want to look for some Durst 'Printo' motorised tanks if you're serious about getting quality colour prints.
    Last edited: Feb 23, 2018
  9. You do not need to get a "color enlarger". Omega made dichroic color heads that will fit on your D II enlarger. You will still be able to use it to print B+W.
    markdavidson likes this.
  10. Have you printed B&W yet.?
    Are you aware of the temperature and darkness requirements for color printing.?
  11. RA-4 color printing can be developed at room temperatures (e.g., 68F for two minutes) in trays using Kodak RA Developer/Replenisher RT, making it very easy. Drums, fancy processors, and high temperatures are not necessary. The developer is followed by bleach-fix and a wash.

    If the filter drawer on the enlarger is used, yellow, and magenta filters are used for color balancing. Generally they are made of acetate, not gelatin. For color negatives, you will not use cyan filters. Do not use red, green and blue filters in the filter drawer; it won't work. Red, green and blue filters of good quality, usually gelatin, can be used if inserted in the light path under the lens one at a time. Color balance and density is adjusted by varying exposure time with each filter, but this is the most cumbersome way to do it. As discussed earlier a color head is the easiest, but more expensive way.
  12. I decided to follow the advice to pick up a color enlarger, and found a nice Beseler 23C with a Dichro 23dga Colorhead on it... Guess I have TWO enlargers to master! lol...

  13. As well as I remember it, Unicolor had a system many years ago to do separate exposures for red, green, and blue.

    That saved the cost of the full set of CP or even more, CC, filters.

    For enlargers without a filter drawer above the lens, you normally use expensive CC filters,
    but Unicolor had a filter wheel that would work below the lens.

    Also, the adjustment of the times for each filter is just slightly easier than computing the change in filters and exposure.

    But used sets of CP filters should be available easily now.
  14. I once tried to use a tri-colour printing system - a sliding set of RGB filters and a 'tray' that screwed to the lens. What a fiddle! And unless the enlarger is rock-steady and built like a tank, there's always a risk that moving the filters will displace something and result in a slightly blurred print when the 3 exposures don't completely align.

    Most colour-correction guides are designed around the CMY single-exposure system, and converting between CMY density changes and tri-colour exposure times isn't easy.

    In short, you might save a trifling amount in not buying a full set of CP filters, but you'll likely spend a fortune in wasted paper and chemicals trying to get the hang of tri-colour exposures.

    IME, trying to cut corners with colour printing is an exercise in frustration and futility. I didn't start to get consistently decent colour prints until I had a dichroic colour head, colour analyser, voltage stabiliser, precise electronic timer and mechanised paper processor.

    Since used colour darkroom gear is in low (almost zero) demand, I see no reason not to buy some, or all of the gear I listed above. The initial outlay will be quickly recouped in saved materials and time.
  15. I'll just toss in that color heads work great for B&W printing with multigrade paper also.

    Ilford at least publishes the color head enlarger settings for the full range of contrast grades with their papers. I have the chart cut out and taped to the front of my enlarger. They list "single filter" and "dual filter" settings-I suggest using the dual filter ones as the exposure stays more consistent when changing contrast.

    I have two enlargers, one of which has a color head and the other a standard condenser head. I'd print everything on the color head if it weren't for the fact that it's 35mm only.
  16. Unicolor made a device with little color filters, which you put over a piece of color paper, with a diffuser over the lens.

    That would give the R, G, and B times (at the cost of one small print).

    Note that such devices give the R, G, and B times directly, but it needs a not so easy conversion to C, M, Y filters.

    But now there are electronic color meters.
  17. There is some good info here but the first thing I would recommend is to master B&W printing first.

    You can learn a lot of good practices that will help you as you move into color.
    Next, find a good manual on basic color printing. Or call Alan ;)

    It is critical that you get exposure correct before starting to correct color. As Alan noted above he offers some starting points for printing. I would note that on your color head you set the dials at 80Y and 40M. For printing negatives Cyan always stays at zero.
    I would note that the final filter pack may differ dramatically from the starting point depending on the film, film processing chemistry used, paper, paper processing chemistry used and even the types of processors used for film and paper (drum vs. tank vs tray).

    Good luck and have patience.
  18. Yes. Much more critical than with black and white.

    Color negative films have a low Gamma, maybe about 0.5, which is corrected with an appropriately high Gamma for color paper.

    The rule on filter selection is the complementary color, and half the value, of the filter that when you look through corrects the color.

    The low Gamma of films allows for the large exposure latitude, needed for simple cameras, along with the assumption that color printers could afford an appropriate exposure/color balance meter.

    Years ago, I did some Ektachrome 1993 printing. That is, color reversal paper, which does not have the high Gamma of negative paper. Getting the color balance right wasn't all that hard.
  19. Both b&w and color printing have their issues, but which one is best to start with is debatable. With b&w you have the issue of contrast of the negative to deal with, which can vary with different films and their development, and frequently has to be, but can be, dealt with when printing. With color, contrast is less controllable, but less variable with film, but you must deal with color balancing. It may seem daunting at first but quickly comes with experience, and after establishing starting balances for different films.

    B&w printing requires a minimum of developer, stop bath, and fixer, but if done in trays you only need developer and bleach-fix for color, and like b&w, can be done at room temperature. Lastly, with b&w, one has to choose from a larger selection of paper types and developers, and if advanced learn things such as divided development and divided fixing, clearing agents, wash aids, toners, etc. With color, there are fewer papers and the RA-4 process is simple and standardized. So if I were to suggest one to start with, or try to master first, it would be color, with less overall variables to learn than b&w.

Share This Page