Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,206   Posts: 1,531,878   Online: 1022
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 16
  1. #1
    David Lyga's Avatar
    Join Date
    Nov 2007
    Location
    Philadelphia, PA USA
    Shooter
    35mm
    Posts
    1,235

    Two questions about enlarging

    I have an Axomat 5 35mm enlarger and it does all that I need done. But, for about three years I have had a 3" x 3" square of drafting film (available cheaply in any art supply store) inserted into the filter drawer in order to convert the light from condenser into diffusion. I like the really even results. (For focusing, I simply temporarily pull out the drawer so that more light will reach the easel.) Does anyone else like this simple method?

    Also, is it true that a blue light will result in slightly sharper prints, due to the fact that you now do not have to worry about all the various colors present in tungsten 'white' light needing to be focused? - David Lyga

  2. #2
    NedL's Avatar
    Join Date
    Aug 2012
    Location
    Sonoma County, California
    Shooter
    Multi Format
    Posts
    784
    Images
    14
    I only have a cold light, so don't know about the first part, but that's interesting.

    As for the blue light, I guess it wouldn't matter much for fixed grade paper and might matter very slightly for VC paper, since no lens is perfectly achromatic. I'm not sure how much UV or violet light gets through an enlarging lens ( and film! ), probably not much, but it might make more difference up at that end of the spectrum. Maybe someone has done a calculation to show that these aberrations are smaller than the "CoC" or grain size on paper....

  3. #3
    David Lyga's Avatar
    Join Date
    Nov 2007
    Location
    Philadelphia, PA USA
    Shooter
    35mm
    Posts
    1,235
    Ah, since 'no lens is perfectly achromatic' NedL this becomes all the more reason to be concerned with such lens' inability to focus all colors at the same time. Thus, by allowing ONLY ONE color, blue, to hit the paper maybe that deficiency can be solved. And maybe I am being naive here but I wanted to pose this in order to receive reaction. Thank you. - David Lyga

  4. #4
    NedL's Avatar
    Join Date
    Aug 2012
    Location
    Sonoma County, California
    Shooter
    Multi Format
    Posts
    784
    Images
    14
    Hi David,
    You like to ask "provocative" questions, to provoke thought, I mean! So I'll add to your question. When we look at the world with our own eyes, in color, presumably the lenses in our eyes are not perfectly achromatic either. Our brains probably use the color variation to enhance our perception of patterns and edges and textures etc... So perhaps if we could make a print using perfectly monochromatic light, perfectly focused, it would look less natural and lose information compared to the "micro-blur" in the gradation of tones caused by slight chromatic aberration? In other words, would this kind of sharpness be too much of a good thing at the expense of important contrast? Perception of sharpness is more than resolution... it's not obvious to me that a perfect monochromatic projection would appear sharper!

  5. #5

    Join Date
    Oct 2009
    Location
    Central Florida, USA
    Shooter
    Multi Format
    Posts
    3,919
    Quote Originally Posted by David Lyga View Post
    Also, is it true that a blue light will result in slightly sharper prints, due to the fact that you now do not have to worry about all the various colors present in tungsten 'white' light needing to be focused? - David Lyga

    Microscopists use this principle of using blue light, light with shorter wave length, to obtain the sharpest image possible. BUT, they are looking at objects at 1000x magnification and trying to extract finer resolution at that extreme magnification. They also use Apochromatic lens so that convergence error is minimized. But again, they are worried about it at an extreme magnifications.

    B&W paper is already mostly sensitive to blue/green spectrum only. Magnifications we are talking about isn't nearly as extreme either. Provided that you are using quality lens, I doubt it'll make any visible difference.
    Develop, stop, fix.... wait.... where's my film?

  6. #6
    polyglot's Avatar
    Join Date
    Jun 2009
    Location
    South Australia
    Shooter
    Medium Format
    Posts
    3,186
    Images
    12
    If you use only blue light on VC paper, you will get an extremely high contrast image. You also need some green light to activate the lower-contrast layer(s) and thereby get an appropriate image.

    For any quality 6-element enlarger lens, the focal differences due to wavelength are not an issue. You should be able to make prints of the grain from slow fine films.

  7. #7

    Join Date
    Apr 2010
    Location
    SF Bay Area, California, US
    Shooter
    Multi Format
    Posts
    275
    I recall a similar method to diffuse the light in a condenser enlarger.
    I think they used a piece of frosted/ground glass or a piece of white plexiglass (which also soaked up more light than the frosted glass).
    I don't know why I did not try it myself.

  8. #8

    Join Date
    May 2011
    Location
    South Africa
    Shooter
    Multi Format
    Posts
    458
    Images
    14
    Well, I am sure your approach will make it a bit easier to print from slightly scratched negatives. That is one of the main reasons a diffuser source is preferred over a condenser source. As for blue light: If you use VC paper, it will simply give you the highest contrast the paper is capable of. So you would have to use graded paper. Not in principle a problem, but then you can use any pure colour, and get into the part of the spectrum to which the paper is most sensitive. It might be that colour is blue, I don't really know. Green would be better for your eyes to work in. I would only do this if my enlarging lens was not very good. I don't have that problem, since I use Nikkors, Rodenstocks and Componons. They are all good enough that I don't have to bother with monochromatic light. Given the hassle of working with graded paper, a decent enlarging lens seems a cheaper and more efficient solution.

  9. #9
    LJH
    LJH is online now

    Join Date
    Nov 2008
    Location
    Melbourne, Australia
    Shooter
    ULarge Format
    Posts
    542
    In one of his videos on YouTube, Clyde Butcher is shown enlarging with blue light.

  10. #10

    Join Date
    Jul 2006
    Location
    Oklahoma, USA
    Shooter
    Med. Format RF
    Posts
    680
    I used to use a frosted cut glass above the condensers in a Omega B-22. It added about 50% to the print times and lowered the contrast by no less than 1/2 grade. The concept works.
    RJ

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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