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View Full Version : Flourescent-light 'glow' a problem?



Eric Thomson
24-Sep-2004, 23:10
I'm pretty new to darkroom proceedure and self-taught so please excuse a possibly dumb question. When I turn off the flourescent lights in my darkroom to load film into film-holders, I notice the tubes glow for a very extended period. There is still a noticeable flourescing after I've finished loading a dozen sheets. Is there a possibility of fogging from this faint light source?

Thanks

Pete Watkins
24-Sep-2004, 23:19
I have experienced problems in my darkroom caused by flourescent tubes. I now remove the tubes to another room before I do any loading film or processing film or paper. The probmlem is real. Best wishes. Pete.

Joel Brown
25-Sep-2004, 00:02
Eric, I had the same problem years ago. Yes you will fog your film. It will probably happen to the top sheet of film in the box that is exposed while you are loading another into the film holder. As each sheet in the box takes it's turn being the top sheet it is being exposed to your flourescent tubes. Try waiting at least half and hour after turning out the lights before loading your film. I was using Arista 125 film at the time. Between each sheet was a thin tissue of paper. That paper was exposed on every sheet of film from the flourescent lights. Get rid of the the lights or find another room to use. Best of luck. Joel

Michael Veit
25-Sep-2004, 00:16
Do all flourescent tubes glow? I've seen this problem referred to several times now, but I swear my tubes don't do it. I load film within 6 feet of the extinguished overhead flourescents without any problem.

Paul Moshay
25-Sep-2004, 01:43
I was using two 8 foot 5000k tubes in my darkroom until a friend suggested that they have an after-burn. I tested this way. At night I entered the darkroom and did not turn on any lights. I sat in the dark for 15 minutes (the longest time doing nothing) and covering my eyes with my arm, turned on the lamps for 15 seconds, then off. At that time I uncovered my eyes and could plainly see the tubes glowing so bright I could have read the newspaper, as my eyes had been used to the dark. I ditched the fluorescents for incandescent lamps.

Huib
25-Sep-2004, 01:49
Hi,

In my darkroom tubeslight do not glow when switched off. I once noticed that tubeslight can glow if you have them wired incorrectly to the switch operating them. If you have installed the switch in the 0 wire, tubes will glow, if you have installed the switch in the live wire tubes will not glow/flicker. Best to use a switch that switches both wires at once.

Huib

www.huibsmeets.com

Øyvind Dahle
25-Sep-2004, 04:09
I have 230V system with 115 on each wire (same system as Albania). I do not have a switch, so I unplug them. They still glow, so I cover them with aluminium foil, and that's good enough for darkroom use, I haven't tried to load film there yet, but I will check thorougly before I do that.

Øyvind:D

Brian Ellis
25-Sep-2004, 04:16
In its Darkroom Guide or somewhere else, I forget exactly where, Kodak recommends that you wait 10 minutes after turning off a fluorescent light before opening film or paper. I used to do that after turning off my two 40 watt 48" lights located in the ceiling of my darkroom but it was a pain so I stopped and didn't have any problems with fogged film or paper. However, my darkroom has an unusually high ceiling, about 12 feet. If the lights were closer I suppose it could be a problem. I'm not sure that being able to actually see a glow is the key to whether it's a problem or not.

Chris Gittins
25-Sep-2004, 06:57
It's the phosphor on the inside of the tube that glows. When you turn the light on you deposit energy in the phosphor and have to wait for that stored energy to bleed off once you turn the light off. As noted above, unplugging the light doesn't speed the process up. Incandescent bulbs don't have a phosphor so are a simple way around the problem.

Chris

Ed Pierce
27-Sep-2004, 10:36
You really can't beat flourescent lights for general use. Yes they do glow and yes they will fog film.

I've solved the problem by making a 'barn door' out of cardboard, and hinging it to the fixture with picture wire on one side. To use the light, I swing the cardboard up out of the way and hook it to a hook installed in the ceiling. To cover the light, I swing it back and hold it in place with a paper clamp.