Zone VI Variable Cold Light Enlarger in community college

Discussion in 'Large Format' started by mike_troxell|2, Sep 4, 2003.

  1. I just enrolled in a community college darkroom class because I was
    told that they had a 4x5 enlarger and I don't have a darkroom at the
    moment. I was pleasently suprised when I got into the darkroom to
    find that they not only had a 4x5 enlarger but it had a Zone VI cold
    light variable speed head on it. I've always used graded papers
    before and have never used a variable speed light head. Noone in the
    darkroom is familiar with the 4x5 enlarger since noone there uses LF
    (don't ask why they have the enlarger, I don't have a clue. I'm just
    grateful that they do have it). Does anyone who is familiar with the
    Zone VI variable cold light head know what settings I would use to
    simulate a grade #2 paper?
     
  2. Mike, it depends on who makes the VC paper you are using.
     
  3. I'm planning to use both Forte Elegance and Kodak Polymax Fine Art VC papers. So there is no "standard" setting equivalent to a #2 graded paper? It depends on which paper you are using? I was hopeing there was a standard setting I could use as a starting point for testing papers. I still have some Bergger #2 paper that I normally use. What if you are using a graded paper such as Bergger with a Zone VI VC cold light head. Do you just set all the VC controls to 0 and print like you normally would with a cold light head?
     
  4. Mike;
    Check your e-mail for details on split printing with a Zone VI head.
     
  5. Does this Zone VI have a controller with three knobs labeled "Hard", "Soft" and "Brightness"? As stated above it depends on the paper, but grade 2 should roughly be found by dialing in equal amounts of "Hard" (blue) and "Soft" (green) light -- the dials on the Zone VI controller for hard and soft are each labeled A-G if I remember correctly -- On the 5x7 VC Zone VI I worked on I just set both dials to "D" for grade 2.
     
  6. Mike,

    Variable contrast papers are not equal. The range of available contrasts varies considerably between papers. Some papers give a wide range of contrasts; others offer only a narrow range. Some papers may offer evenly spaced grades while others have grades which are clumped together and unevenly spaced. The actual contrast you get from a sheet of paper depends on the paper itself, the light source used and to some degree the developer used. If you wanted to pin the grades down, you would use a step tablet to determine the range of values printable for each setting. This, however, is a bit redundant. What should remain constant for any paper is that if you increase the contrast of the light source, you increase the contrast of the print. (And conversely, of course, for contrast reduction.) What you really want to determine is the appropriate contrast range for the negative you're printing and your own aesthetic values. If you think about it, it doesn't really matter whether it's called a Grade 2 or a Grade 1 or a Grade 5. What matters is that the print values end up on paper where you want them.

    The light source you have is not a "variable speed" light source, but a variable contrast light source. Nevertheless, the change in contrast is effected by changing the relative intensity of the two tubes (blue and green) in the head. By starting with both contrast controls set to "maximum", the head will produce the most light, hence print the fastest. I would suggest that you start there and see what a straight print looks like. If you need more contrast, you then reduce the "soft" light (green) which in turn produces a bluer output and a harder contrast. In the same manner the contrast may be reduced by reducing the "hard" (blue) light.

    If you try two or more different VC papers, you will be surprised at how different they can be, both in their contrast response and overall printing speed. To start out I would strongly suggest that you begin with one VC paper and learn its quirks before trying to use several papers. Otherwise there are so many variables that it can be very disconcerting.

    If you use graded paper with the VC head make sure that the controls are set the same each time. (That probably would mean "maximum", again, for the fastest printing speed.) The contrast won't change if you change the setting while using a graded paper. But changing the contrast setting on the head changes the spectral output of the lamp and will have an effect on printing speed.

    I would strongly recommend that you consult one or more of the texts currently available on printing which cover variable contrast printing techniques.

    Good luck,
     
  7. Since there isn't a "standard" grade 2 there really is no way you could simulate "a grade 2 paper" that would apply to all papers.

    Also, the contrast range of conventional black and white enlarging paper actually varies very little from one brand to another. The range is about 2.0 to 2.2 density units, a very small difference. What does vary is how that available range is apportioned among the shadows, midtones, and highlights. If you happen to have Ctein's book "Post Exposure" available, there's an excellent discussion of this in the chapter dealing with enlarging papers.

    I use an Aristo VC4500 head, which I believe is very similar to the Zone VI head. Since it's really impossible to have a "standard" grade 2 or a "standard" grade 3, and since there isn't a reciprocal relationship between changes in the numbers and changes in contrast, I don't find it very useful to try to relate the numbers to paper grades. I think you'll find that as you use the head you'll quickly determine a place to start to produce a more or less normal proof print with a more or less normal negative (with the Aristo head I usually begin at 2.7 with Ilford Multigrade IV FB and at 2.0 for Kodak Polymax Fine Art). I think you'll also find that the contrast doesn't increase or decrease proportionately with increases or decreases in the numbers. With the Aristo head and Kodak Polymax Fine Art paper there's a "flat spot" in the area of 3.0 to 3.5. In other words, there is very little contrast change from 3.0 to 3.5 even though if you thought in terms of paper grades you'd thing there would be a half grade difference. Otherwise the contrast changes are more or less consistent with increases or decreases in the numbers. If you're lucky enough to have a reflection densitometer available it's pretty easy to make a chart that correlates the contrast change with the change in numbers on the head. Phil Davis did that for me when I attended one of his workshops and it has been very useful.

    Good luck, once you become familiar with your school's variable contrast head I think you'll be very happy using it.
     
  8. Thanks for the advice everyone. I've been printing with graded papers for years but VC is a whole new area for me to explore.
     
  9. One word of caution regarding the Zone VI VC head... Forget it if
    you're printing from stained pyro negatives (such as from PMK).

    Unfortunately, I bought this head about the time I was getting into
    PMK in the early 90s and the combination of the yellow/green
    stain and blue (hard) florescent tube resulted in verrrrrry
    looooong exposures and a limited range of contrast from VC
    papers.

    A typical exposure with this head for an 11x14 print was over 3
    minutes using a stained HP5 neg. Same neg with condenser
    light source was about 20-30 seconds.

    As I used more and more pyro in my LF photography, I finally
    sidelined the VC head (which does work great for non-stained
    negs) and re-tested everything to standardize on the trusty
    Beseler condenser unit. And in doing so picked up about 1/3
    stop more film speed on average.
     

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