BW amount of M and Y filtration?

Discussion in 'Enlarging' started by crumpet8, Feb 13, 2018.

  1. Patrick Robert James

    Patrick Robert James Subscriber

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    Forget about grades. Terrible idea from the manufacturers. Concentrate instead on tone.

    Personally I split print with the hardest and softest filters. On my Saunders that is Magenta and Yellow just like on your color head. Don't mix the two. Just make two exposures, one through maximum Magenta and one through maximum Yellow. Usually it is best to start with the Yellow and only look for the highlight tones you want. Once you get that dialed in, do the same with the Magenta to fill in the deeper tones. Usually everything will fall into place nicely. You can also do much more effective burning and dodging this way as well.

    When you mix both into one exposure you create consistency errors between the "grades". You end up trying to hit a moving target which is no fun. There are charts which are supposed to ameliorate this problem, but turning three dials to a specific number every time you want to change something is just no fun at all.
     
  2. MattKing

    MattKing Subscriber

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    There is a common misconception that the various components of the emulsion on a variable contrast paper have different contrasts. They don't - they have different speeds.
    For simplicity, it is easiest to think of there being two components - a blue sensitive high contrast component and a green sensitive low contrast component - even though many variable contrast papers use more than two.
    Each emulsion component adds density to the result, and the end result is the sum of the contributions of all the components.
    The so-called high contrast component has higher speed, and adds more density in response to the same intensity of light than the so-called low contrast component.
    You vary the apparent contrast of the result by varying the proportions of the blue and green light.
    If you want a particular range of tones to have more "pop", print those tones at a higher contrast (use an appropriate balance of blue and green light). Then adjust the contrast and exposure of the other tones to look the way you want them to.
    If you want to perform an interesting experiment, make a good looking print from a fairly normal, mid-contrast negative using the split grade method. Say you end up with a 12 second low contrast exposure and a 6 second high contrast exposure. Then, without changing anything on the enlarger, "split" that result into two to make two more prints: one using only the low contrast filter for the same 12 second exposure and the other same using only the high contrast filter for the same 6 second exposure.
    Most likely, you will be amazed at the result. The low contrast filter only print will be relatively close to the combined print, and the high contrast filter only print will, relatively speaking, be just a faint ghost of other.
     
  3. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    I started photography back in the early 80's back then, some folks still printed with graded paper. I learned to print on Kodak Polycontrast paper. I've been printing the old fashioned way by either changing grades with under the lens filters or using a color head for 30 years. Didn't start to split grade print until a few years back and I thought it was brilliant. You should give it a go!
     
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    crumpet8

    crumpet8 Member

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    Thanks Bill, learning a lot here :smile: I googled that zine vi enlarger and saw it has blue or green dials instead of the cmy options on my head. I guess this allows for increased range of settings as you can increase the amount of blue or green rather than subtract from the white light of the enlarger bulb?

    Anyways, I didn't quite catch your fine tuning example... More time with blue is the equivalent of decreasing yellow filtration right? But then if thats your low conrast part of split grade then wouldnt more time make your white points darker?

    Less green = more magenta so I see how that would give you a more contrast and probably a less grey white.

    How am I doing?

    In regards to the last paragraph on changing to a lower contrast, the whites becoming greyer is assuming you are looking after your black point rather than white point? Cant you achieve the same white or black point with all contrast settings? Its just that at a low contrast you may have to choose between only having a true white OR true black. and then with a higher contrast you risk losing tone nuances and detail but it would be easier to achieve a white and black point?
     
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    crumpet8

    crumpet8 Member

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    Thanks Matt! starting to make sense, but I was wondering why the blue sensitive high contrast is controlled by the yellow if adding yellow (reducing blue light) creates lower contrast? And the same with the green low contrast and Magenta filtration.

    As I'm writing I'm thinking about negative density and its role here. I guess as emulsions develop faster in the initial stages then exposing a high contrast neg with lots of blue would create high contrast compared to if one were to expose the other component (green) instead? OR is it more that the two components are in different layers (like film emulsion) and that the physical amount of silver sensitive to either blue or green light is less dense? But again I thought it would be the green/magenta light/filtration that would be most dense as this controls higher contrast.

    In regards to adding the two together I could now see the blue being the main exposure (as it's faster) and the magenta just adding a little extra to the total equation as you suggest in your experiment? I've actually been doing half of this for my test strips for later reference. After split grade printing I'll make a print of the low contrast first exposure for future printing reference.
     
  6. cowanw

    cowanw Member

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    Conceptually one starts with white light, Starting with 100% white light one can only take away. So conceptually the yellow or magenta is added to decrease the blue or green.
    Try this on.
    the blue /yellow system brings the white and black points in or out from the endpoints, mainly the lower half.
    The green/ magenta system expands or contracts the greys from the middle, mainly the upper half.
    Both control contrast but in different ways
    You wrote
    "Anyways, I didn't quite catch your fine tuning example... More time with blue is the equivalent of decreasing yellow filtration right? But then if thats your low conrast part of split grade then wouldnt more time make your white points darker?"

    I think that blue/yellow would normally be described as the high contrast part of split printing. Of course it cuts both ways as you increase or decrease the effects with more or less yellow, but again normally one adds yellow to the white enlarger light to tame contrast (in combination with time) and push out the endpoints of white and black (mainly blacks; it takes a heck of a lot of blue to change the white point, it takes a heck of a lot of green to change the black point) until just a touch of black exists somewhere in the print (to your taste).
    Then add magenta to white light, to decrease green and bring your white point from grey to white.
    You wrote
    "In regards to the last paragraph on changing to a lower contrast, the whites becoming greyer is assuming you are looking after your black point rather than white point? Cant you achieve the same white or black point with all contrast settings? Its just that at a low contrast you may have to choose between only having a true white OR true black. and then with a higher contrast you risk losing tone nuances and detail but it would be easier to achieve a white and black point?"

    This is essentially correct. Although in the example, we were talking about using grade 4 or 5 as one part of split printing and it might be that your negative requires no green at all. Of course, by "looking after your black point rather than white point", you mean changing exposure times which is as you know the third (and/or fourth) variable.
     
  7. DREW WILEY

    DREW WILEY Member

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    VC papers differ, and some seem to require a token amt of both emulsions getting exposed to achieve DMax. An easy way to do this is to use some white light overall, then selectively tweak for richer blacks (M or B), or else texture fill-in in the lighter tones at lower contrast (Y or G light).
     
  8. MattKing

    MattKing Subscriber

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    Magenta filters subtract green from relatively full visible spectrum light, but leave blue and red in the light. As the papers are not sensitive to the red light, a magenta filter has the effect of increasing the relative amount of blue in the light that actually reaches the paper.

    Yellow filters subtract blue from relatively full visible spectrum light, but leave green and red in the light. As the papers are not sensitive to the red light, a yellow filter has the effect of increasing the relative amount of green light in the light that actually reaches the paper.

    I expect that the reason so much of our equipment uses subtractive based, magenta and yellow filtration is that the systems are based on incandescent or halogen light sources that are more effectively filtered using magenta and yellow filtration. If the original technologies had easily available red, blue and green sources instead, additive colour (and contrast) control would probably be more common.

    The various variable contrast components are equally and evenly but randomly distributed throughout the emulsion on the paper.

    The main exposure is generally the green sensitive one. The blue sensitive one just provides a small but very effective amount of strategic higher density in the spots where it matters most to create apparent contrast.
     
  9. RalphLambrecht

    RalphLambrecht Subscriber

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    this may help
     

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  10. pentaxuser

    pentaxuser Subscriber

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    Ralph's free and generous download says it all. I urge everyone to instantly download and keep this who has any interest in grades, exposure calibration etc. These downloads have a habit of somehow disappearing or having a 404 error years later

    At the very least it forms a basis for a educative discussion. A great pity that a similar chapter isn't available on Perceptol Minimum Quantity :D

    pentaxuser
     
  11. DREW WILEY

    DREW WILEY Member

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    Matt - additive colorheads are much more difficult to engineer, and the filters are much denser, requiring more light. I have a couple of additive systems. But for split printing VC paper, one can simply use white light and attach high quality Green vs Blue filters right to the enlarger lens. I use 47 blue and 61 green with a cold light.
     
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    crumpet8

    crumpet8 Member

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    Ok, this combined with Matt’s explanation that the relationship between layers is relative seems to click for me. Where I thought the magenta green was steering the black and white points from the endpoints it’s aftually that the amount of green reaching the paper is reduced, thus leaving a greater ratio of blue and apparent contrast. Correct me if that’s still wrong :smile:

    When you mention this upper and Lower halves, how does this relate to negative density? I understand how low contrast filtration affects mainly the lower (white-grey) half values and magenta the upper, but how pronounce do the effect is would depend on how much contrast is in the negative?
     
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    crumpet8

    crumpet8 Member

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    Thanks so much! I’ll print this out at school and read it next week :smile:
     
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    crumpet8

    crumpet8 Member

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    Great explanation Matt, think I’ve got it now :smile:
     
  16. cowanw

    cowanw Member

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    Negative density and contrast are two different things. Density speaks to times of enlargement exposure.
    As to your second sentence, I am not sure how to think about that. If your negative is very contrasty you will not be using any blue light anyway and vice versa; sort of self correcting.
    You might consider getting a Stouffer negative and print that under differing scenarios to see what the effects are.
     
  17. CMoore

    CMoore Subscriber

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    If i understand you correctly.....
    1. With Yellow (Max) you are looking at the Brightest/Whitest areas that are important.?
    2. With Magenta (max) you are looking at the Darkest/Blackest areas that are important.?
    Thank You
     
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    crumpet8

    crumpet8 Member

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    Seeing it’s been a while I’ll try answer... With split grade printing you are correct.

    The first exposure/test strip is usually at low contrast (high yellow filtration) and you look at what highlight value you like.

    Then, make another test strip with high contrast (high magenta) on top of an already exposed low contrast exposure based on the first. Now you look for what black values you like.

    Print with the two exposures selected and let the rest of the tones fall into place.
     
  19. MattKing

    MattKing Subscriber

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    That is for un-manipulated split grade printing where you are essentially aiming for the same print you could obtain with a single exposure at an intermediate contrast setting.

    Split grade printing excels when you split different parts of the image in different proportions - certain areas are printed with one proportion, other areas are printed with another proportion while other areas are printed with another proportion. Combine that with dodging and burning in different areas, and you end up with a well crafted print.

    As I indicated earlier, I tend to base my main exposure split decisions on how the important mid-tones appear. I add or delete contrast and dodge and burn in the shadow areas to achieve the detail and black I want there. And I delete or add contrast and burn or dodge in the highlight areas to achieve the detail and luminosity I want there.

    By the way, for most scenes with a range of contrast and tones, many people do prefer to start with the low contrast exposure tests. If, however, you are working with a predominantly low contrast scene - like a photo taken in foggy conditions - it usually works best to start with the high contrast exposure tests.
     
  20. adelorenzo

    adelorenzo Subscriber

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    I highly recommend Gradient Light: Art and Craft of Using Variable Contrast Paper by Eddie Ephraums. I got my copy for a few dollars they are not hard to find.
     
  21. CMoore

    CMoore Subscriber

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    Thanks for those last Three Replys.
    What i have been doing so far is what Matt has Mentioned/Suggested.
    Maybe printing 3/4 of the frame at 20M...dodging the upper 1/4 for All/Most/A Lot of the exposure, and then go back and Burn THAT Area at 60M (these are all just arbitrary) for as long as "necessary".....Stuff Like That.
    I am still Very Much a "beginner", but i kind of do all this by Intuition/Educated Guessing.
    I know there are Numbers/Ratios that suggest what time to add to an exposure for how much Filtration is added, but God Help Me.....i am just not that Smart/Articulate.
    So i just kind of guess, write down (approximately) what i have done, and then adjust from there.
    Since joining APUG, i have read many times that guys like to do the Y-max and M-max method.....so i have always been curious.
    Just one way to find out i suppose.....:smile:
    Thanks Again
     
  22. DREW WILEY

    DREW WILEY Member

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    The less complicated you make it, the better. Some people enjoy crunching numbers, and that's fine, but had darn little with getting good prints. You just need a timer and some kind of appropriate VC filtration. The rest becomes easy with practice.
     
  23. sepiareverb

    sepiareverb Subscriber

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    Hah!

    I taught film and darkroom classes for 15 years, and think starting with an excellent negative that looks good on the proofsheets at grade 2, one should print that negative a few times: with standard filters, with the split-grade approach, with water bath development and even on graded paper to learn the ins and outs. This can all be accomplished in a single session, and by working with the same negative one can quickly get a feel for what the different approaches can do.

    My personal preference is to use a VC Head and adjust filtration for burning as needed, a sort of hybrid split grade. I generally print at 1.5 to 3, and will burn in with grade 0 or 5 as needed. I also often use a brief grade 5 exposure to firm up maximum black. I have arrived at this method after using only graded papers for a very long time. The quality of the VC papers became apparent when I replaced my Zone VI VC Head, which was only capable of about a two grade range in practice with all of the papers I tested. I have not looked back.
     
    Last edited: Feb 22, 2018
  24. DREW WILEY

    DREW WILEY Member

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    So someone has to fish around for the odds n' ends of ancient grade 2 paper still left in the world, then gr 3, 4, etc to understand the lingo first? - grades which never really were standardized brand to brand to begin with ?
     
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    crumpet8

    crumpet8 Member

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    Hey Matt,

    Seeing as it’s a ratio or relationship between blue and green light that affects contrast, would the contrast always be the same if the ratio was the same but overall amount different? If so, is it just the exposure time that changes then?
     
  26. MattKing

    MattKing Subscriber

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    Yes and no.
    Yes, if the adjustments available to you are linear and they match between the filters.
    In other words, does a change from 30 to 60 on the magenta scale have the same effect on the amount of green light as a change from 30 to 60 on the yellow scale has an effect on the amount of green light.
    If not, no.
     
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