Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,548   Posts: 1,573,022   Online: 852
      
Page 3 of 3 FirstFirst 123
Results 21 to 23 of 23
  1. #21

    Join Date
    Oct 2006
    Location
    Pasadena, CA
    Shooter
    Multi Format
    Posts
    813
    Images
    9
    Gary,

    I'll measure the light output with my incident meter and keep it for reference. It's probably a handy chart to have around anyway...

  2. #22

    Join Date
    Sep 2002
    Location
    Willamette Valley, Oregon
    Shooter
    Medium Format
    Posts
    3,684
    Quote Originally Posted by David A. Goldfarb View Post
    For the same enlargement factor, at the
    same aperture, any lens of any focal length
    will produce the same exposure time.
    I've given it some thought and now believe the
    above statement the more likely correct. Two other
    non-related matters were considered in making my
    first statement.

    One; point light sources and the inverse square law
    came to mind. Two; years ago I went from a 75mm to
    a 105 when working close to the base board. More room
    to work but had thought my exposure times longer
    without actually testing. Dan

  3. #23

    Join Date
    May 2005
    Location
    Woonsocket, RI USA
    Shooter
    35mm
    Posts
    2,725
    Quote Originally Posted by PVia View Post
    So, Gary...if I dial in all 3 at 25, and the chart says to use 15Y 25M, it would be 25C, 40Y, 50M ?
    Yes, although cyan filtration is irrelevant to most B&W paper, at least in theory, so you could do 25C/40Y/50M, 0C/40Y/50M, or 100C/40Y/50M and they'd all print the same. Remember, cyan is "minus red," and since most B&W papers are (nearly) insensitive to red, adjusting the cyan filtration will have no effect. Again, this is in theory. In practice, there might be a tiny effect, particularly if your cyan filter blocks any non-red light. I did some tests once and found no effect with Agfa MCP310RC paper and my enlarger, but it's an oddball Philips PCS130 with PCS150 controller, which uses separate red, green, and blue lights rather than a white light with cyan, magenta, and yellow filters.

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