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View Full Version : Loading film in the presence of "glow-in-the-dark" aperture scale...



fecaleagle
27-Jul-2014, 12:33
I recently picked up a Durst S-45 from Don Dudenbostel, and I was just in the darkroom getting ready to load some film when I noticed that the aperture scale on one of the lenses glows in the dark. I put it in a box just to be safe, but should I be concerned about this when loading/unloading film?

lenser
27-Jul-2014, 12:40
I would be deeply concerned about any light source of any level. It seems silly to take chances with film being so scarce and expensive.

fecaleagle
27-Jul-2014, 13:34
I would be deeply concerned about any light source of any level. It seems silly to take chances with film being so scarce and expensive.

Seems like a silly feature to me. It's a really nice Fujinon-EX 135mm f/5.6, but I may need to let it go or paint over the scale, because I know it's going to drive me crazy having to remember to remove it every time I'm working with film in there.

John Kasaian
27-Jul-2014, 13:53
I'd cover it to be on the safe side.

David Schaller
27-Jul-2014, 14:02
Throw a towel over it. I do that with my timer.

cyrus
28-Jul-2014, 00:43
I don't really think this affects normal speed film. I regularly load and unload film in a darkroom which has plenty of glow-in-the-dark things hanging around including the dial on the old Gralab with no negative results.
I also put little glowing stickers on strategic corners to guide me out of the darkroom in an emergency.

BetterSense
28-Jul-2014, 04:41
I load film 3 feet to a Gralab 300 timer. It's fine. I only wish film were fast enough to be fogged by such a light! If you can't see your hands it is plenty dark enough.

hoffner
28-Jul-2014, 05:28
It's fine. I only wish film were fast enough to be fogged by such a light! If you can't see your hands it is plenty dark enough.

Really? Astronomers have been taking pictures in a light where you cannot see your hands for ages.
My military Luminox watch always leaves my wrist when I load film. For a good reason. You can even read maps in its light.

Luis-F-S
28-Jul-2014, 06:01
I typically try not to have any light sources with film. I've taped the little green dots in the GFI protected outlets in my dark room, try not to have any "glow" light switches, and have my Zone VI developing timer on it's lowest setting plus I have a piece of cardboard over the display to direct it away from the film when processing. Enjoy the Durst S-45, it's a wonderful enlarger! LFS

lenser
28-Jul-2014, 06:01
When I was setting up my first darkroom while in high school, the owner of the local camera store, quite the expert, said that same thing. Only he said "if you can't see your hands AFTER FIVE MINUTES, it is safe to load film".

I still trust that advice completely.

Keep in mind that it takes our eyes several minutes to adjust to darkness after turning out the lights. In that time, the film is happily doing what it does, gathering and recording light in the dimmest of circumstances.


I load film 3 feet to a Gralab 300 timer. It's fine. I only wish film were fast enough to be fogged by such a light! If you can't see your hands it is plenty dark enough.

hoffner
28-Jul-2014, 06:35
all you need to know is - film has much better light gathering capability than your eyes. If you don't believe it try to make a precise difference between a 1/50 and 1/25 of a shutter speed in your eye. .. You will soon loose your silly confidence.

Harold_4074
28-Jul-2014, 13:11
For a real-world sanity check, take an incident light meter into the darkroom, put it where the film usually is during loading, and point it in the direction of the suspect light source. Then see how long an exposure you would need with an f/1 lens.

If the time seems marginal, maybe you should also think about reciprocity failure...

Kirk Gittings
28-Jul-2014, 14:20
A GrayLab timer can fog Tri-x tray developing at about 4 feet. I didn't believe it but after testing it turned out to be true. So I needed to see the timer-it sat on a wire shelf above the sink. So I cut out a 18x18" piece of black Gatorboard to put under the timer and block a direct line of sight to thye film and that solved it.

towolf
29-Jul-2014, 06:33
all you need to know is - film has much better light gathering capability than your eyes. If you don't believe it try to make a precise difference between a 1/50 and 1/25 of a shutter speed in your eye. .. You will soon loose your silly confidence.

Your eyes are way more capable of collecting low flux of photons in scotopic vision (https://en.wikipedia.org/wiki/Scotopic_vision).

After calcium adaptation your rods can manage to detect down single photons. Your film needs several seconds to minutes to aggregate enough photons to convert the silver.

hoffner
29-Jul-2014, 06:50
After calcium adaptation your rods can manage to detect down single photons. Your film needs several seconds to minutes to aggregate enough photons to convert the silver.

Good luck with loading your film in a time under several seconds to minutes!

towolf
29-Jul-2014, 07:22
Good luck with loading your film in a time under several seconds to minutes!

You're taking my reply wrongly. I was merely comparing low light sensitivity of film and human retina. Where your camera needs seconds to minutes expose something resembling your visual perception, your eyes are feeding your brain "live video".

Scotopic vision starts at EV -9 and stops at EV -13.6. Good luck metering that.

lenser
29-Jul-2014, 07:59
You're taking my reply wrongly. I was merely comparing low light sensitivity of film and human retina. Where your camera needs seconds to minutes expose something resembling your visual perception, your eyes are feeding your brain "live video".

Scotopic vision starts at EV -9 and stops at EV -17. Good luck metering that.

You just alluded to a condition that may belie what you are trying to explain. You mention the condition of the film accruing the light in the camera which has a more finite limit on what light is available to the film. The conditions of loading or unloading film in the darkroom will imply that each sheet is totally exposed to any slight amount of existing light with no lens/aperture limitations. It may be a small difference, but a highly important one.

The only true way to know is to test by leaving a completely unexposed sheet of film out on the loading table with an object of some kind on the film. Give it reasonable amount of time under the actual conditions, say 30 seconds. and then process the film.

If the object left a shadow image you're in trouble.

Drew Wiley
29-Jul-2014, 08:21
I learned about this the hard way a long time ago. Different films have different degrees of sensitivity. And then even when you don't think fogging is going on, there can be some subtle degradation of the crispness of shadow values. Darkrooms should be dark. Period. Any glow anything should be in a position where the film cannot see it. I never use one of those old-fashioned Gralab timers except in an emergency, and then it's put on a shelf BELOW the sink. In the film room, anything with a visible LED or luminous whatever is oriented in such a manner that nothing reaches the work station where the film is loaded, in other words, where I can't even see that light source myself from that position. And all the walls are black. An exception would obviously be blue-sensitive or ortho graphics films and conventional black and white printing papers where specific safelights are an option.

towolf
29-Jul-2014, 08:49
You just alluded to a condition that may belie what you are trying to explain. You mention the condition of the film accruing the light in the camera which has a more finite limit on what light is available to the film. The conditions of loading or unloading film in the darkroom will imply that each sheet is totally exposed to any slight amount of existing light with no lens/aperture limitations. It may be a small difference, but a highly important one.

I was merely objecting to what I quoted, i.e. "film has much better light gathering capability than your eyes", as a vision scientist.

I wasn't talking about fogging on film lying openly over long periods.

Corran
29-Jul-2014, 09:21
There's been a couple of times that I've loaded some film and after my eyes acclimated I could see my hands clearly. One time was so bad I almost trashed the 6 sheets I had loaded. But I decided to shoot with them anyway and guess what, clearly no fog. Glow in the dark stuff? Nope, not going to be a problem.

hoffner
29-Jul-2014, 09:33
I wasn't talking about fogging on film lying openly over long periods.

Yet that is what is discussed - the film doesn't need to see, all it takes to fog it is to gather some light over a certain period of time.

Drew Wiley
29-Jul-2014, 13:41
Yeah... what's the problem with a tiny little hole in your tire? It isn't flat (yet).