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  1. #21
    JBrunner's Avatar
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    Quote Originally Posted by Reinhold View Post
    This is a repeat of my post back in 2003 on afterglow...

    "... Just for the heck of it, I took a reading of afterglow with a Pentax digital spot meter held up against a bare 4' warm white flourescent tube and took a reading within 5 seconds of turning it off (in my darkroom, of course).

    Wanna guess what it read??? Zeeeero.

    Ok, lets assume that the light was actually E.V. 0.9, and couldn't trigger the meter to respond with a positive reading. How long would a medium speed panchromatic film have to sit on a countertop (4 feet below the light) before it would show noticeable fog?...??

    Also... afterglow diminishes with time... I can't visually see any glow after a minute or so, even with eyes that are fully dark acclimated. When I process 400 speed film or Konica 750 IR film, I wait 2 minutes before opening the wrapper. Been doing it for nigh onto 30 years now...

    I routinely latensify film in the same room (using a #3 filter in a Kodak beehive safelight) for 16 minutes, and have yet to get even a hint of uncontrolled fogging from fluorescent lights.

    Afterglow is a not a bugbear in my darkroom..."

    Reinhold

    www.classicBWphoto.com
    The afterglow of most fluorescent sources falls mostly outside of a meter's spectral sensitivity, so it isn't a surprise that the meter read nothing. Paper, however, has a broader range, and may "record' what the meter doesn't. Most likely a practically undetectable low grade fog, dinging up those sparkling highlights (less so for panchromatic film, and unexposed film might just get a tiny little kick to B+F, usually no biggie). Many a person searches for a technique that will give them that range they see in certain prints. Most of the time it isn't a technique that is at fault, rather a cruddy lighting, safelight, leak, or afterglow situation in the darkroom when printing. Even though paper is slow by comparison to a lot of film, it spends a lot more time out of the box, so the cumulative effect can be much more apparent. Again I am talking about something that borders on insidiousness. Most people notice gross problems right away. I have seen this tiny little dinge gremlin more than I care to recount, even in "perfectly fine" darkrooms that have been in use for years. (not saying there is anything wrong with yours)

    The only way to know for certain is to perform a safelight test with pre-flashed paper, the same paper you print, under your personal printing conditions. The slight pre-flash recommendation is particularly relevant in regard to weak sources of contamination. It might not show with unexposed paper. Testing is the only sure thing. Everything else is speculation.
    Last edited by JBrunner; 09-13-2010 at 06:09 PM. Click to view previous post history.

  2. #22
    Martin Aislabie's Avatar
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    Quote Originally Posted by JBrunner View Post
    Testing is the only sure thing. Everything else is speculation.
    How very true

    Martin

  3. #23
    RalphLambrecht's Avatar
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    Quote Originally Posted by Adrian Twiss View Post
    ... I intend to replace them with 6ft 70 watt fluorescent tubes in a twin light fitting. I was going to opt for daylight tubes with a colour temperature of 6500K. ...
    Adrian

    Incandescent lighting is preferred over fluorescent lighting. Incandescent bulbs are designed for frequent on/off switching. They have no lengthy ramp-up and are immediately at full power, which they maintain consistently. The bulbs do not continue to glow after they are turned off, and their color temperature is similar to typical domestic and gallery lighting, making incandescent lighting more conducive to accurate image tint evaluation.

    A dedicated location for dry or wet print evaluation is an important feature of a well-designed darkroom. The area should be evenly illuminated and closely simulate final viewing conditions. Prints produced and evaluated in brightly lit darkrooms end up looking too dark in dimmer environments. A 60-100W opal tungsten bulb, a distance of 1-2 meters from the evaluation board, provides an illumination of around EV 6 at ISO 100/21°. This setup simulates rather dim display-lighting conditions and is ideal for dry print evaluation. However, don’t forget to consider print dry-down when evaluating wet prints.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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