Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,836   Posts: 1,582,437   Online: 707
      
Page 3 of 3 FirstFirst 123
Results 21 to 26 of 26
  1. #21
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,381
    Images
    4
    The Darkroom Automation web site has an application note explaining how variable contrast paper works (and sometimes doesn't):

    http://www.darkroomautomation.com/su...vcworkings.pdf

    Contrary to common belief the various emulsions in VC paper all have the same intrinsic contrast. The only difference is that one emulsion has a green sensitizer added to it - it is the same sensitizer used for Orthochromatic (blue-green sensitive) film. This is very old technology, the addition of erythrosine dye to the emulsion to make it orthochromatic was discovered in the late 1800's. Dupont came up with the idea of 2-emulsion VC paper - called Varigam - in the late 30's.

    The reason that a high contrast filter is magenta rather than green is that VC filters also pass red light. The addition of red results in more illumination when you are dodging and burning. Try putting a deep blue filter in the holder and then hold a cardboard dodging card under the lens -- it is very difficult to see just where in the image you are with the card. The original VC filters were green to blue in color, but user's didn't like them, and that's where the change to yellow to magenta filters originated. Color heads also use yellow & magenta, while VC cold light heads are stuck with green and blue.
    Last edited by Nicholas Lindan; 02-20-2013 at 12:49 AM. Click to view previous post history.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  2. #22

    Join Date
    Feb 2012
    Shooter
    Medium Format
    Posts
    39
    Quote Originally Posted by MartinP View Post
    ... One exercise that used to be given to most learners was to make a grid of (small, postcard sized) prints of a neg with a full range of tones that prints easily on a mid-grade. Print each grade and vary exposure by, say, 1/2 stops across a range of a couple of stops and arrange the prints on a board so that you have your 'standard' print in the middle. Going horizontally (change in exposure) or vertically (change in contrast) you see an example of the change in exposure or contrast, by whatever units you have used, and can more easily relate what you see on a future print with what you might want to change to get it where you want.
    Martin, Thanks for your reply. The exercise sounds like a good idea to me. I did some printing last night and compared a non-filtered print to my #2, #2.5, #3, just to see what would happen. I got very confused as my non-filtered print is drastically different than what I get with a #2 MC filter. Your exercise sounds like just what I need. I'll do this before attempting to print anything else. Now I just need to figure out which of my negatives are "normal" enough to use. I think I'll mount the prints on a piece of cardboard to hang in the darkroom for future reference. Thanks a lot.

  3. #23

    Join Date
    May 2005
    Location
    Daventry, Northamptonshire, England
    Shooter
    35mm
    Posts
    7,149
    Just as a matter of interest what could the unfiltered print be compared to grade-wise and what was the paper? If I recall correctly Ilford says that its VC paper unfiltered corresponds to grade 2

    Thanks

    pentaxuser

  4. #24

    Join Date
    Feb 2012
    Shooter
    Medium Format
    Posts
    39
    Quote Originally Posted by pentaxuser View Post
    Just as a matter of interest what could the unfiltered print be compared to grade-wise and what was the paper? If I recall correctly Ilford says that its VC paper unfiltered corresponds to grade 2
    Thanks
    pentaxuser
    I went into the darkroom just now and turned on my enlarger and guess what I noticed? The stupid negative is on Ilford's XP2 (C41)film. The resulting negative isn't black and white, but BROWN and white. I feel very silly and you (and anyone else) are welcome to come over and kick me in the ass, as it should have been obvious to me that brown negatives are going to require a different approach. I didn't realize it last night as I'd been under the red lights a long time and I guess I went a little color blind.

    But for reference, the unfiltered print is lower in contrast and very dark. I am using Arista's RC and FB papers, as they seem to need almost identical exposures as each other. I'll look through the forums for how to best print C41 "B+W" negatives but I will also make the test print grid as Martin suggested. I think it will do me a lot of good.

  5. #25

    Join Date
    May 2005
    Location
    Daventry, Northamptonshire, England
    Shooter
    35mm
    Posts
    7,149
    Quote Originally Posted by jeddy-3 View Post
    But for reference, the unfiltered print is lower in contrast and very dark. I'll look through the forums for how to best print C41 "B+W" negatives but I will also make the test print grid as Martin suggested. I think it will do me a lot of good.
    Thanks for the response. If the print is overall very dark then I wouldn't expect the use of filters to correct that. They will increase contrast and that way appear to brighten the highlights compared to the midtones and shadows so yes parts of the print will look brighter but you need to look at overall exposure as well. If a low contrast but "too dark" print has its contrast raised but at an exposure that simply equates to the "too dark "exposure on the low contrast print then it will still be too dark.

    I might be stating what is obvious to you but a sparkling print is a combination of the right exposure for the highlights with a right exposure for the shadows so the details can be seen. I agree the exercise of printing at all the grades is very educational


    pentaxuser

  6. #26

    Join Date
    Feb 2012
    Shooter
    Medium Format
    Posts
    39
    Thans Pentaxuser,
    You're correct, it was very overexposed but I had done so purposefully as I had hoped for a very dark image with only a few bright highlights. With use of even the #2 filter the highlights were "overcorrected". I will come back to the print later; I'm trying to run before I can walk.....crazy to say as actually I'm hobbling around on crutches for 2 months.

Page 3 of 3 FirstFirst 123


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin