Split contrast filtering

Discussion in 'Enlarging' started by Robert, Jun 18, 2003.

  1. Robert

    Robert Member

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    Lets see if I understand this.

    Step #1 Do a test print with the #389 green filter.
    Step #2 pick the time on the print that looks best
    Step #3 expose the whole print to the time from step #2
    Step #4 Now use the #68 filter
    Step #5 Pick the best time and use that to make up the print.

    Am I right? I'm ignoring anything like the need to dodge/burn. Lets assume my negative is magically perfect-)).
     
  2. lee

    lee Member

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    I would use a Green #58 and a Blue #47 and I would do the blue first. Look for the first hint of black and use that for your blue filter time. You can always correct. Then do the green. Look at the highlight for this test. But yes, that is the sequence.

    lee\c
     
  3. Robert

    Robert Member

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    Thanks.
     
  4. Les McLean

    Les McLean Subscriber

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    The filters suggested by Lee will give you the best result but I would suggest that you start with the green filter to establish the correct exposure for the highlight and do the blue filter second to determine the contrast and tonality for the whole print. If you start the blue you will see a contrast in the testthat is not possible to maintain for as soon as you lay soft filtration on you will reduce the contrast. I prefer this way for I think of it as building the contrast. Perhaps the best appraoch would be to try both ways to see which works best for you for neither is wrong.
     
  5. Robert

    Robert Member

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    I do have a #47 and a #58 but they are only 3"x3" too small for the enlarger. I guess I could use them under the lens but the last time I tried that it seems not the best solution. How much of a problem will the Roscoe filters cause me?
     
  6. Robert

    Robert Member

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    I did it this morning. The process seems great. Much easier then me trying to figure out what the "right" contrast filter would be. The thing that surpised me was just how much light the filters passed. To my eye the filters pass very little light the paper on the other hand had no problem. I started out with a longer then normal test print figuring I'd need it but turned out it wasn't needed.
     
  7. magic823

    magic823 Member

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    What would I use on a Saunders 4550XLG VCCE Enlarger (since you change set filter grades using a dial)?
     
  8. Donald Miller

    Donald Miller Member

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    What I do on my 4550 is to use a low contrast (grade one) setting to do a test strip to determine the highlight tonality. Then I do a second test strip by exposing a second sheet of paper with the high value (low contrast) time followed by a second test strip on that same piece of paper at a grade five setting to determine low value times.

    The actual printing then becomes X seconds at grade one followed by X seconds at grade five.

    The burning and dodging will then be determined by the tonal range and the contrast grade at which it was printed.
     
  9. Jeremy

    Jeremy Member

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    Is this easily accomplished using a color head? Maybe using all the way yellow and then with magenta cranked up? For some reason I feel like I should know the answer to this question and feel dumb asking, but how else am I going to learn.
     
  10. Donald Miller

    Donald Miller Member

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    Jeremy,
    I have not used a conventional dichroic head for this purpose but it is my understanding that yellow filtration would be used for the low contrast and magenta for the high contrast.
     
  11. Les McLean

    Les McLean Subscriber

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    Robert,

    Use maximum magenta for the hard filtration but don't use maximum yellow for the soft filtration, all that happens is that you add density giving a longer exposure but with no significant increase in the degree of softness achieved. I've used all sorts of different enlargers in the 10 years that I have used this method of split grade printing and found that about 70 yellow is the optimum filtration.
     
  12. Jeremy

    Jeremy Member

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    Thanks, Les, I'll have to play around to find out what is best for me, but a starting point is always helpful!
     
  13. Donald Miller

    Donald Miller Member

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    On my Saunders 4550 VCCE it seems that the soft filtration is more nearly cyan then yellow. That makes sense since in additive color filtration of VC papers the colors used are blue and green. I think that Magenta is the subtractive of green and that Cyan is the subtractive of Yellow.
     
  14. glbeas

    glbeas Member

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    Correction, cyan is the subtractive of red, blue is the subtractive of yellow.
     
  15. Donald Miller

    Donald Miller Member

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    Hmmm. On my color enlarger the filtration is Magenta, Cyan and Yellow. I know that from what the manufacturers state the colors to which the variable contrast black and white papers are sensitive are blue and green. I know that my 4550 VCCE uses magenta and another color that doesn't really appear (to my eye anyway) as yellow. Perhaps I am color blind. It must be yellow though from what you say. Thanks for the information.
     
  16. lee

    lee Member

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    Donald, if you use c and y together and add numbers you can reduce m. if you use c and m together and add numbers you can reduce y. maybe something like that is going on here. but glbeas is correct that cyan is the subtractive of red and yellow is the subtractive of blue and magenta is the subtractive of green. Are the colors wheels marked on the enlarger head? I would think that they should be. Just a thought.


    lee\c
     
  17. Donald Miller

    Donald Miller Member

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    Lee,
    Nope on the 4550 the only designation is paper grade. On my older Omega medium format dichroic the colors are marked as I had indicated earlier. I imagine that what you are indicating must be the way that Saunders approaches the filtration for their VCCE head. It has been years since I worked with color (about 20) my memory doesn't serve me well after that long.
     
  18. baronfoxx

    baronfoxx Member

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    I use a Leica V35 enlarger fitted with a Heiland dedicated splitgrade head, the two colours used are yellow and magenta.
    the process is automatic with the yellow exposed first followed by the magenta, there is also the facility to reverse the process and I can detect no difference either way in 12"x16" prints.
    Iam very happy with this system :D I hope this information helps.
     
  19. inthedark

    inthedark Member

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    Don, I think glbeas is color correct rather than b&w correct. Color head have Magenta, cyan, and yellow which are the colors of the dyes in color paper that are printed with green, red, and blue light respectively. Making red/cyan, green/magenta, and blue/yellow the proper opposites. But since b&w paper is orthochromatic the red of the equation gets thrown out which essentially makes your observation accurate as well.
     
  20. magic823

    magic823 Member

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    Based on everything said here, I tried split grade printing this weekend on some 16x20 I printed. The process was very easy and the prints turned out great. I noticed that the blacks seemed to be much richer, while the highlights maintain their crispness.

    It certainly sold me on the process.
     
  21. Jeremy

    Jeremy Member

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    I spent my darkroom time last night on split contrast printing with my color head and the difference is amazing! My negative are usually quite contrasty, but between the 4x5 neg and the split printing I'm getting extremely smooth skin tones. It took me a while to get it right (I was also trying to mess around with fstop printing, but became so befuddled I had to call it a night not to mention my homework). The difference is so great that I've even decided to use the portrait (more a 4x5 headshot) as my next postcard... I've been having trouble deciding what I should actually send.
     
  22. inthedark

    inthedark Member

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    Okay, now I am confused. Les yousay yellow doesn't work to soften contrast but then you say you use a 70 yellow???? Anyway, I have found all of the old contract filters that were used to assist in halftoning and the "add contrast" filters are varying densities of magenta and the "lower contrast" filters are all shades of straw or yellow if you will.
    But, what I don't get is the whole split filtering concept, here. Are you applying a filter then shading out the parts that you don't want effected by that filter, applying another filter and exposing the parts you were just shading?

    As for theCMY vs RGB, cyan opposes Red, yellow opposes blue, and magenta opposes green. The problem with trying to discuss these things is. . . What color is yellow to you may not be the right yellow as far as photography is concerned. I have been fighting with this concept since I have been trying to incorporate color into the shop without a dichroic head. I have reverted to terms like cherry and salmon rather than red, because although they are both red; cherry brings up green in negative printing, while salmon brings up cyan. Straw yellow brings up a colbalt blue, while lemon yellow brings up more of a lavendar or indigo blue.

    Anyway, I would like to understand this whole split contrast filtering concept. AND I wonder is it applicable to color or just b&w. I have been trying to find a way to adjust contrast in color, but so far I only adjust the color, not the contrast. Or with the neutral density filters, I simply change the exposure time but the image remains about the same in the end.
     
  23. Les McLean

    Les McLean Subscriber

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  24. Donald Miller

    Donald Miller Member

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    Jill,
    The matter of split contrast filtering is applicable to black and white variable contrast materials. It does not apply to fixed contrast (graded) black and white papers.

    With variable contrast materials there are two separate and distinct characteristic emulsions. One is primarily affected by yellow or green and the other is affected primarily by magenta or blue. (The reason that I listed pairs of colors is that some variable contrast light sources use subtractive and some use additive colors. In the case of Lee's aristo cold light head he filters with blue and green. In the case of my Saunders I use magenta and yellow. Magenta and blue are the colors that affect high contrast and the colors of yellow and green affect low contrast.

    Normally printing on variable contrast paper is done by varying the ratio of one light color to the other and this arrives at an infinitely variable grade (within the confines of the papers limits).

    In the case of split contrast printing the printing is separated into two distinct exposures with one being a soft contrast exposure and the second being a high contrast exposure. One of the advantages of this type of printing are that burning and dodging is more controllable within the two exposures. In other words if I wanted to dodge a shadow area, I would due this during the high contrast exposure since this is the exposure that affects primarily the low values. If I wanted to burn a highlight down, I would do this during the low contrast exposure since that exposure affects primarily the lighter tonal values. Additionally, I feel that I am able to arrive at the correct contrast on the print more rapidly then if I am choosing a single contrast setting.

    To summarize, instead of printing a negative at, for instance, 20 seconds at grade 2.5(in a single contrast setting on variable contrast paper)...I may end up doing a 10 second exposure at grade one and a second exposure of 8 seconds at a grade 5.

    To expand on Les's explanation. The optimum (maximum effect) of the yellow filtration is 70 units, in his experience. He is saying that to add 120 units, for instance, will do nothing more then 70 units except to add density to the light path and therefore increase printing exposure time.

    Hope that this explains this for you. Please feel free to question if you do not understand.
     
  25. inthedark

    inthedark Member

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    Actually yes it does. When Jeremy said he was getting smooth skin tones I was hoping he meant color.
    I didn't understand why variable contrast works the way it does. Your explanation is excellent. Now I can incorporate that into better outcomes as well. Thank you very much. You should open a school, you teach so well.