[Leica] RE: darkroom update

[George Huczek <ghuczek@sk.sympatico.ca>]

At 01:17 PM 29/10/98 -0800, Dave wrote:
>Tina:
>
>>>You wrote:
>
>>>Don't make it too dark!
>
>My darkroom is about 9'X 12'. I put a Thomas safelight in the middle. I
>could hardly call it a darkroom anymore. I did some extensive testing for
>fogging and discovered a problem. It happened when I preexposed the paper
>to a certain threshold, which I now do for all safelight testing (i.e.
>identify and give max exposure for zero density, then do the coin test). I
>blamed the Thomas and took it down. I left up the smaller lights. Turns out
>the fogging was caused by one of the smaller lights. The filter was old so
>I replaced it and the problem cleared up. I tested the Thomas again and
>there was no problem. Still I took it down. I couldn't get used to working
>in that much light. Plus I'm 6 foot and the light hung down to 5 feet ll
>1/2 inches. I banged my head every time I got overly excited about a print
>and sprinted across the room to turn on the 5000K lights.
>
Dave,
I have tested my Thomas safelight and I have found that it does indeed
cause fogging a problem.  Mine is about 5 feet above the work counter where
I handle my printing paper.  I found that about a five minute exposure
caused fogging on Ilford MGIV.  Usually I do not have to keep paper on the
counter for that length of time, but to remedy the problem I closed down
the vanes on the Thomas safelight so that they are just barely open when I
have to handle a print longer than usual.  The vanes cut down the light
intensity in the darkroom, but the safelight gives out so much light anyway
that this is not really a problem once one gets used to working in slightly
dimmer conditions.
   The fogging can actually come in handy if one finds the threshold limit
of a particular brand of paper.  It can be used to preflash the paper for
longer, more carefully controlled times than blasting the paper for one or
two seconds on the enlarger, like most darkroom sources suggest.  Most
mechanical timers do not give precise time intervals anyway, especially for
short durations, so preflashing to bring details into overexposed highlight
areas becomes a matter of guesswork using the normally prescribed
techniques.  Longer safelight flashing can work well, as long as the
safelight is positioned so that the illumination is even across a large print.

   
 _
[o] -GH