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accidentally exposed raw stock


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#1 Jiekai Liao

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Posted 27 April 2006 - 12:56 PM

I was in a pretty light proof room transfering 400 feet of "Eastman High Contrast Positive Film2 7363" to 4 seperate daylight spools so that I can shoot on a bolex. I had taped up the edges of the door; there are no other areas of possible light leaks into the room. Ten minutes into the transfer, I turned my back and discovered this glaring red bulb of light in a hidden corner of the room, which I had not discovered. It is a really small bulb, I have no idea whether it is the kinda light they used in photographic dark rooms or not, but in any case, my film is possibly exposed to that light for ten mins straight. The light is approx 20 feet away from the rewinder where I am working on the transfer. I immediately sealed whatever I have not transfered, taped up the red light, and then proceed on and finished the transfer.

I know it is very difficult to judge the extent the film is being exposed to this small bulb, as I have provided very minimal information. But considering the fact that the bulb is small, and the stock is High contrast extremely low sensitivity film stock, can I remedy the situation by rating the stock slightly higher? Do you think that the film is totally burnt out in that ten mins, and I should not consider using it at all?

advice needed. thanks!
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#2 John Pytlak RIP

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Posted 27 April 2006 - 01:25 PM

I was in a pretty light proof room transfering 400 feet of "Eastman High Contrast Positive Film2 7363" to 4 seperate daylight spools so that I can shoot on a bolex. I had taped up the edges of the door; there are no other areas of possible light leaks into the room. Ten minutes into the transfer, I turned my back and discovered this glaring red bulb of light in a hidden corner of the room, which I had not discovered. It is a really small bulb, I have no idea whether it is the kinda light they used in photographic dark rooms or not, but in any case, my film is possibly exposed to that light for ten mins straight. The light is approx 20 feet away from the rewinder where I am working on the transfer. I immediately sealed whatever I have not transfered, taped up the red light, and then proceed on and finished the transfer.

I know it is very difficult to judge the extent the film is being exposed to this small bulb, as I have provided very minimal information. But considering the fact that the bulb is small, and the stock is High contrast extremely low sensitivity film stock, can I remedy the situation by rating the stock slightly higher? Do you think that the film is totally burnt out in that ten mins, and I should not consider using it at all?

advice needed. thanks!


7263 is mostly blue-sensitive, so it should be fairly insensitive to a dim red safelight. You should process some of the film you suspect may be fogged, along with an unfogged sample, to see if the red light caused any exposure. If not, you do not need to compensate. If you find fogging, don't use the film.

http://www.kodak.com...ves/ti2167c.pdf

http://www.kodak.com....4.6.6.12&lc=en

EASTMAN High Contrast Positive Film II 5363 and 7363 is a medium speed black-and-white positive film that is suitable for making both positive and negative titles. It is also useful for production of printer effects, such as silhouette and traveling mattes. This blue-sensitive film is characterized by high contrast, excellent sharpness, and very high resolving power.


Next time, let your eyes get accomodated to the dark, and look carefully for ANY light source before handling unprocessed film. Don't forget things like a luminous watch or the flashing LED on your cell phone.
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#3 K Borowski

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Posted 27 April 2006 - 05:09 PM

I was in a pretty light proof room transfering 400 feet of "Eastman High Contrast Positive Film2 7363" to 4 seperate daylight spools so that I can shoot on a bolex. I had taped up the edges of the door; there are no other areas of possible light leaks into the room. Ten minutes into the transfer, I turned my back and discovered this glaring red bulb of light in a hidden corner of the room, which I had not discovered. It is a really small bulb, I have no idea whether it is the kinda light they used in photographic dark rooms or not, but in any case, my film is possibly exposed to that light for ten mins straight. The light is approx 20 feet away from the rewinder where I am working on the transfer. I immediately sealed whatever I have not transfered, taped up the red light, and then proceed on and finished the transfer.

I know it is very difficult to judge the extent the film is being exposed to this small bulb, as I have provided very minimal information. But considering the fact that the bulb is small, and the stock is High contrast extremely low sensitivity film stock, can I remedy the situation by rating the stock slightly higher? Do you think that the film is totally burnt out in that ten mins, and I should not consider using it at all?

advice needed. thanks!


There should be no damage whatsoever. I'm not exactly sure what kinda bulb you have, but even with sensitive colors, if it was 20 feet away, and you only had the film out from inside the reel to break it up for a few seconds (i.e. only a few seconds of line-of-sight exposure) there should be no detectable difference in the base fog. It doesn't sound like you're talking about a full-sized safelight, as I"m sure you'd notice that in 10 seconds, not 10 minutes. Agreed with what John said, print film, like print paper in B&W is not sensitive to red at all. In fact, I wouldn't be surprised if that light were perfectly compatible with that film. My 1947 Naval Photography guides contain some descriptions of 16- and 35mm printing done then, which was all B&W save Kodachrome. They have actual pictures exposed either with a darkroom light or by simulation of one, so it was apparantly fairly common practice in the days before color to make prints under red safelight, as the print film needed only be sensitive to blue. Red is generally the safest when it comes to print films, having a narrow bandwidth and being furthest away from the blue area of the spectrum that silver halides are naturally sensitive to.

To give you an example of a case where a color that a photographic material IS sensitive to, I was making some prints with RA-4 photopaper, which, because it is designed for prints from color negative film, is sensitive to all wavelengths of the visible spectrum. The speed of modern papers is rated by some at 400ASA. Anyway, I use glow-in-the-darkgreen tape, which the paper is sensitive to, but is very dim. Not to mention there is usually some residual light leaking in from the upstairs, as the door of the darkroom is obstructed from closing by an effluent waste hose running from some film and paper processors outside the darkroom into the darkroom drain. So I was printing 3.5x5 inch proofs one day, by hand, and I didn't have that size easel at the time. I decided to use that glow-in-the-dark green tape to make a makeshift printing area, charged it up with light and made 2 prints on each 5x7 inch sheet of paper I used. To make a long story short, there was fogging, but ONLY because the paper was in contact with the tape for several seconds, and it was SENSITIVE to the wavelength of light coming from the tape.

So do your test, but only use a small piece of film. I'm certain you'll be fine. If the test shows no signs of fogging, feel free to use that light in the future so you can see what you're doing!

Regards.

~Karl Borowski
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#4 John Pytlak RIP

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Posted 27 April 2006 - 08:09 PM

Sometimes a light that appears "red" to the eye, could have enough energy at the lower wavelengths to fog a blue sensitive film, so I strongly suggest testing. Here is my SMPTE technical paper about darkroom lighting for color products like Kodak VISION Color Print Film:

http://www.kodak.com...on/page01.blind
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#5 K Borowski

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Posted 27 April 2006 - 08:50 PM

[quote name='John_P_Pytlak' date='Apr 27 2006, 09:09 PM' post='102534']
Sometimes a light that appears "red" to the eye, could have enough energy at the lower wavelengths to fog a blue sensitive film, so I strongly suggest testing.

No disagreement intended; test to be sure. Any fogging that occurs will be minimal if it is a real red safelight, which is what it sounds like from your description, iakeij. If it is not a true safelight, or more of an orange, then you might have some very very slight fog, certainly most of your stock will still be useable, since it tended towards the red end of the spectrum. Why not go back into the darkroom and check to see what it is for sure and eliminate any speculation as to what it was? You'll note in the paper John provides, very similar to another darkroom guide I use as my working guide, that even safelights can fog film given enough time, as no safelight is perfect. However, 20 minutes of ambient exposure to light that you couldn't see until that amount of time had passed leads me to believe that it is one of those small enlarger safelights, designed to be especially weak and be set near the enlarger so that the guy printing the pictures can see what he's doing before and after exposure.

Regards.

~Karl Borowski
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#6 Dominic Case

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Posted 28 April 2006 - 12:14 AM

The danger with "safelights" is that the filters can fade over time. They remain about the same colour, but begin to pass traces of wavelengths that they shouldn't. You don't see that till you pick up the fog on the film. And sometimes in a stills darkroom you don't pick up the fog on the film until it gets really bad.

The other danger is that quite often "safelights" are only safe up to a certain level of exposure: a lamp designed to provide distant and general illumination can easily fog film if it is brought up close to an emulsion - the good old inverse square law comes into play.

That said, it sounds as though you would be very unlucky if this particular light fogged your particular roll of film. It's red, it's distant, and it's not bright enough for you to have seen it at first. The film is non-panchromatic, and presumably if you were rewinding it, any given peice of film was only open for a second or two.

A good way to test a darkroom for fogging is to leave a short length of film out on a benchtop or rewind for a long time, with an object such as a coin, or a film spool or can, over part of it. Punch a hole to mark where the object was, and get the section processed. If you can see any trace of the object where it has prevented fogging, then the light isn't safe.
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