Archived posting to the Leica Users Group, 2001/07/30

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: [Leica] Light in the darkroom?
From: Tina Manley <images@InfoAve.Net>
Date: Mon, 30 Jul 2001 19:50:40 -0400
References: <5.1.0.14.2.20010730163234.01db8160@127.0.0.1>

At 12:00 AM 7/31/01 +0200, you wrote:
>Tina writes:
>
> > Fluorescent lights can continue to fog film
> > even after they've been turned off.
>
>Really?  How?


I've always heard this.  A quick search on google turns up this:

"Technically, the afterglow is phosphorescence, not fluorescence, but the 
effect on your film is the same. There are no general rules: there are many 
different tubes out there, and they all have different afterglows. In the 
darkroom I use, the ceiling fixtures will noticeably fog RA4 paper up to 
quarter of an hour after they are turned off.
A standard darkroom safelight test will tell you if your fixture is causing 
a problem. The afterglow usually has blue or even ultra-violet components, 
so even ortho-lith film can be fogged. On my RA4 paper tests the 'fogging' 
showed up as a 5-10cc shift to yellow, rather than a noticeable darkening 
of the print. "

and from the Kodak site:

"Never have fluorescent lamps in the darkroom! Fluorescent lamps remain 
glowing after the power is turned off and will cause film fog."


Tina

Tina Manley, ASMP
http://www.tinamanley.com

Replies: Reply from Tina Manley <images@InfoAve.Net> (RE: [Leica] Light in the darkroom?)
In reply to: Message from Tina Manley <images@InfoAve.Net> (Re: [Leica] Light in the darkroom?)