How much daylight in the darkroom can film/paper tolerate?

If you know light is leaking why bother to test when it is very easy to block it. My darkroom has two doors and a wall of windows. I covered the windows with a couple of layers of garden plastic attached to a piece of moulding on top secured with "L" hooks and on bottom also with moulding and Velcro. For the doors I used blackout cloth stapled to dowel sticks top and bottom also attached on top with "L" hooks and long enough on bottom to cover any leaks. They are wider than the doors so that is covered. I only use one of the doors so it is simple to remove and roll up that cloth like a scroll. I use red safelights and have never had a problem light leaks.

http://www.jeffreyglasser.com/

1. Weather strip the doors. If you can find it, there is a very nice, thin plastic that folds into a V when installed. You can use two of them, one on the sill and on on the door frame, they work together to provide a nice light block without jamming up the door. Or use any other thin strips.

2. Either paint or use electrical tape around the edges of the door, to minimize the light piping that happens with doors/walls/sills painted white.

3. For windows, I start by covering the glass with stick on light reduction plastic available at any home improvement store. This reduces the light by about 80%. Then use any of the suggested covering methods mentioned before. Once you've put the plastic on the windows, you can simply tape black construction paper over the window (tape it to the frame using black tape), and that will eliminate the rest of the light.

Of course, your final issue is ventilation. Once you've done all this clever sealing, you have also blocked off your air flow.

The OP asks "how much", but not how to achieve that value. Here is the answer.

NONE = No light at all. Some films, as specified by the manufacturer can tolerate brief exposure to a green safelight.

To achieve it, use your eyes. If you can see anything at all, there is light.

PE

some papers can withstand light minimally, it depends on what kind of paper it is.
i have left a box of azo paper open and turned on the room light by accident 5 seconds or less. i thought i was hosed, and my heart sank because light is light and i turned it on exposing 100 sheets of paper.
thankfully it was fine. but that's azo / silver chloride paper for you, it is normally exposed with a 300 watt bulb. if it was any other kind of paper, i would have had to throw it all out.
film, that's a differnt tomato.

They're called DARK rooms for a reason!!!

To add to my earlier post....

Your film is really sensitive to light. You need to make sure that extraneous light doesn't reach it.

Your black and white paper isn't as sensitive to light. If extraneous light reaches reaches it, it will affect the quality of your prints, unless it is very, very dim.

But whether or not extraneous light reaches your film and paper isn't the same thing as whether or not you can see the outline of a door when you look at that door. Your eye is a very sensitive instrument which can detect very low levels of light. And the sort of dim light that one can perceive at the edge of an otherwise closed door is both quite directional and easily blocked.

The real test is whether any extraneous light illuminates, even dimly, those areas of the room where your film and paper might spend time.

Photo Engineer said:

The answer is a red safelight for paper and nothing for film and there is no other answer out there.

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This is a constant, recurring theme on APUG (and other forums). How dark is dark enough? Many darkroom materials have printed warnings on the packaging saying "open in total darkness" or "open only under safelight conditions", etc. It never ceases to amaze me how people cannot understand that total darkness is an absolute, not a range. And safelight is just that: safe, not of low enough intensity.

Yes, it is true that there is a point of the quantity of light beyond which it is necessary to expose film or paper. And the OP's question is what are those points? But the easier solution os to eliminate all extraneous light. No, really, that's the easiest solution. We've all worked in temporary darkrooms (usually baths). But even temp darkrooms have to be made suitable. Light-Proofing is just one of those things.

As for the anecdotal "I have some light in my bathroom and I never fog prints", well, the operative word here is "anecdotal".

If you can see light in your darkroom, no matter how dim, then if you hold a piece of film between you and that dim light, it will vanish. The film is absorbing that light and is being exposed. Light is not "directional" when coming from light leaks like this. If you can see it, so can the film.

PE

David Brown said:

This is a constant, recurring theme on APUG (and other forums). How dark is dark enough? Many darkroom materials have printed warnings on the packaging saying "open in total darkness" or "open only under safelight conditions", etc. It never ceases to amaze me how people cannot understand that total darkness is an absolute, not a range. And safelight is just that: safe, not of low enough intensity.

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Strictly speaking there is (albeit fuzzy) amount of photographic exposure (that can be expressed as total number of photons or electromagnetic energy absorbed by photosensitive material) that leaves no trace whatsovever in terms of density upon development. A single photon can trounce a silver atom from its halide compound, which happens with certain quantum efficiency. This atom may or may not contribute to formation of a grain under the action of developer - again this happens with certain probability (for any given ISO speed) dependent primarily on temperature and surface density of metallic silver atoms. Therefore there exists certain maximum amount of photon influx per unit of area of film that will leave no trace.

Similarly, there is no such thing as total darkness. There are always photons from bioluminescence of certain bacteria, phosphorescence of various materials, static discharge of electrically charged materials, light from electron recombination of free ions in the air, not to mention neutrons from nuclear decay reactions in the rocks underneath and occasional cosmic ray or two. There are no absolutes in this Universe, no total darkness, nor perfect vacuum, no infinite dimensions, timespans, energies and no gods.

Anyhoo, I wasn't asking about these numbers (although just to satisfy curiosity would still be nice to know that number for a film of given ISO speed). Just the experimentally verified effect of light of geometry and intensity as determined by the average leaky bathroom door.

Yes, it is true that there is a point of the quantity of light beyond which it is necessary to expose film or paper. And the OP's question is what are those points? But the easier solution os to eliminate all extraneous light. No, really, that's the easiest solution. We've all worked in temporary darkrooms (usually baths). But even temp darkrooms have to be made suitable. Light-Proofing is just one of those things.
As for the anecdotal "I have some light in my bathroom and I never fog prints", well, the operative word here is "anecdotal".

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It appears indeed that light proofing is the only way to go. And great advice on that subject matter, guys. Thanks a lot. Weatherstripping and black plastic on velcro over the window should do the trick nicely.

Since the amount of light (photons) is usually 3 photons per latent image center, this is very very low indeed. A 1/100th second exposure at f11 admits very little light into a camera and yet it can fully expose a film. Try looking through your camera's lens with the back open sometime and fire it at a nominal exposure and then figure out how that little blip of light can cause so much change in the film. When you are loading reels or hangers, you are exposing the film for minutes! Maybe an hour or so if you are clumsy and drop the film into the kitty litter. - see this story elsewhere on APUG!

PE

Apologies for not reading the whole thread,,, but did anyone recommend just testing to see if it's bad enough to bother "you"? Take a negative you've printed before with good results. Lay out a sheet of photo paper with 1/2 covered with black paper or a book or something,,, let it sit for 5 minutes,,, then expose and develop normally. How much of a "fog" do you see on the uncovered 1/2?

Grif, what is your suggested test for film then?

Oh, and I forgot, yes, phosphorous "emanations" from devices such as wristwatches can fog film. I've even seen it happen with paper. Greenish numbers on your film!

PE

Here's an absolute amateur's opinion. If you load your reel in front of you with your back to very tiny cracks of subdued, diffuse light which are several feet away then you might well get away with it. No-one here can know except you what constitutes a tiny crack of light in your darkroom so if you have to load a film for developing in daylight then you will just have to take a chance. If you can load at night then so much the better.

If it were me I'd try loading at night with my body shielding the film from those cracks of nightlight. If it works then try it in overcast, dull daylight. I would be wary of trying it on a brilliantly sunny day when even small cracks of light can be intense and penetrating.

I have only ever had one roll of Kodak HIE and tried to load it in total darkness as recommended. It took me several attempts lasting several minutes and just before I succeeded I became aware of a change in light in the room. Shock horror, my darkroom blind had not prevented the ingress of a diffused very dim glow of light. I was expecting at least the first few frames to be damaged or ruined but they weren't. OK not totally analogous with loading a film onto a developing tank reel but the instructions as far as I am aware tell you that HIE has to be loaded into the camera in total darkness so maybe there is a slight safety margin. There may be a slight safety margin with film loading into a developing tank as well

If you do decide to have a go, let's us know how you get on. Best of luck

pentaxuser

I should have added that my U.K. light intensity is slightly less than San Diego's. Even in summer we can get all four seasons in the same afternoon so I just wait an hour or so for the winter season

pentaxuser

Photo Engineer said:

Since the amount of light (photons) is usually 3 photons per latent image center, this is very very low indeed. A 1/100th second exposure at f11 admits very little light into a camera and yet it can fully expose a film.

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Very little indeed! After all, people used photographic plates in serious astronomy and astrophotometry, where photons almost literally can come one by one even during awfully long exposures.

Try looking through your camera's lens with the back open sometime and fire it at a nominal exposure and then figure out how that little blip of light can cause so much change in the film.

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Did that many times for fun. Admittedly, it does give an idea of amount of light needed to form an image. Dependance however is logarithmic, so it my escape our linear intuitions.

[/QUOTE]When you are loading reels or hangers, you are exposing the film for minutes! Maybe an hour or so if you are clumsy and drop the film into the kitty litter. - see this story elsewhere on APUG![/QUOTE]

Film is not so much a problem, since I always load it on reels inside the bag, but on one occasion I needed to open up the loaded camera to check and straighten the jammed film. Would be nice to be able to waltz into the darkroom and do it quickly.

As for kitty litter, now, that truly is the real danger since I do have two cats and their litter box is in my "darkroom"! :-D

Jerry_K said:

Like most people in the world I don't have access to a true, dedicated darkroom and have to resort to utilize my bathroom. And like most bathrooms, mine is too far from perfectly light-tight - there is very little light admitted through the narrow slots between the door and the door jams and the floor.

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Work at night. That is what I had to do when my darkroom was the corner of my and wife's kitchen in Japan, until our family got bigger and we moved to a larger apartment... I took a bedroom all for myself!

Tonite I'm finishing the trim on my sliding panel door to one of my darkrooms. The door itself is covered with deep black studio velvet - the best kind.
Then I'll turn really bright lights in the adjacent room. Hopefully after my eyes get fully adjusted to complete darkness, I won't be able to detect anything. That is a printing room. Where I do film work is two more rooms behind that one. Perhaps overkill, but building shift and develop issues over time, so over-doing it in advance saves panic maintenance or rude surprises later. Worse culprits are things like LED panels and glowing hands
on timers - such things go under the sink or countertop where I have to deliberately look down there; the film never "sees" these from where it is
handled or developed.

bence8810 said:

I also heard that film has no tolerance what so ever so whenever I need to work with film (unreeling a 400ft roll into 4 x 100ft rolls) I do it in a darkbag - in my darkroom. This may sound funny but my dakroom is only dark enough for paper but not for film so I do everything in the darkbag and should I ever need to pull my hand out for whatever reason midway (an hour process to unreel the film), i figured sitting in the 99% darkness would help.

For paper I just go with the flow, make sure the little light that comes in besides the door should not directly hit the paper and I've been okay. I put black tape around the doorframe so it wouldn't reflect anywhere but after 5 or so minutes sitting in the dark with safelight off, I can clearly see where the light comes in by the door.

If I were you, I'd keep printing daytime too - no need to limit yourself to nights only. Get a black cloth from someplace and hang it above your door - problem solved. A rolled up towel pushed against the door at the bottom will take care of the light coming in from there.

Ben

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My dark room is dark enough for paper too.

Film gets handled in changing bags. It is not worth the risk that I might have missed some light leak in the darkroom.

Photo Engineer said:

If you can see light in your darkroom, no matter how dim, then if you hold a piece of film between you and that dim light, it will vanish. The film is absorbing that light and is being exposed. Light is not "directional" when coming from light leaks like this. If you can see it, so can the film.

PE

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This is true.

One thing I do when I turn off the lights before I start... I crane my head all around looking for light. I also put my head where the film or paper will be and I look towards the possible sources of leak, gaps in curtains, the ceiling for tell-tale lights left on in the other room (I have a slightly baffled but open gap ceiling for ventilation, so the surrounding also needs to be dark for my darkroom to be dark). When my head is near the floor and I see a slight leak, as long as it is not severe, I can be comfortable knowing the film isn't going to be on the floor (or if it is, it's not long - don't ask how I know)...

My message here is - look from the perspective of the film/paper and you might see a leak that you don't see when you are standing facing the trays.

the beauty of doing retina and lumen prints is you dont' care if there is a little extra light squeeking its way into your darkroom/closet/bathroom/garage
you can load the camera or contact frame with paper or film in broad daylight ! and unload it bright daylight too.
i'm currently using an emulsion that is a fraction of a fraction of iso 1 so it doesn't matter if i have a little bit of stray light or my safelight is wrong.
it exposes with a 300 W bulb i and is "user friendly" for paper negatives, glass negatives as well as contact prints.
enlargements probably require some hypering ... it is f16 @ about 1min in bright sunlight ..

Photo Engineer said:

Grif, what is your suggested test for film then?

Oh, and I forgot, yes, phosphorous "emanations" from devices such as wristwatches can fog film. I've even seen it happen with paper. Greenish numbers on your film!

PE

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Load the reel,,, leave a couple of frames loose, cover the rest with a black cloth,,, same basic thing. I've actually done it with 120, just unroll it a bit with a book holding the reel down,,, and a book holding the end of the film down leaving a frame or so open, and wait "awhile",,, spool it up and see how it looks. you're not going to get any statistically valid results, no r values and so on,,, but quick and dirty to see if the problem is big enough for "you" to be concerned with. After technical judging a couple of photo shows in college I discovered a wide range of tolerance for various things. :-(