How sensitive would Tri-X 8x10 be to infrared light?

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Sean

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I'm still building my infrared night vision develop by inspection system for tri-x 8x10.

I have the goggle which can see infrared light. The idea is to develop each sheet in a glass tray with an infrared light source below the tray aiming up at the film. The result would be like looking at the film on a light table through the goggle. If it works as expected I should be able to see every nuance in the film as it develops. I have found what appears to be a good infrared light source, it contains a small bank of infrared led's. The guy on ebay says it gives off no visible light unless you look directly into the led you can see a very faint red glow within the leds. Is that faint glow going to be enough to fog the film or will the film even see it? I'm hoping it will not see it. I don't plan to leave the infrared light source on the entire time, just at certain intervals. The only way to answer this may be to do a fog test of some kind...
 

David A. Goldfarb

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It should be okay, but if you know the specs of the IR source, you can check it against the spectral sensitivity curve for Tri-X in the technical data sheet at kodak.com.
 
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Sean

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The guy doesn't know. I might just risk it and give it a try. If it doesn't work with that source I can sell it as a 'camcorder night illuminator', then get someone to custom built an IR source with specific specs.
 
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Sean

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This is the one I'm looking at. It's even waterproof which will come in handy incase I spill some chem on it by accident.

3128574_full.jpg
 
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Sean

Sean

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ah, i found a similar item with a wavelength of Wavelength: 945nM

will check kodak's site
 
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Sean

Sean

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ok this is the sensitivity chart. So it looks like 945nm would be way in the clear right? not sure how to read this, thanks!

f002_0360ac.gif
 

David A. Goldfarb

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That's right. 950nm would be way off the chart, so it would produce essentially no density on the neg.
 

David A. Goldfarb

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Of course you could still do a fog test, or in the meantime, if you happen to have an deep red IR filter (which I suppose you might, since I remember that your Traveling Portfolio selections were IR), make a long exposure on Tri-X with that filter and see what shows up on the film.
 

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The fascination with development by inspection completely eludes me. I can take two negatives on the light box and study them under a 10x loupe for two minutes, and still cannot decide which will print best with the #2 filter. How can anyone look at a wet negative for a few milliseconds under green light, or a few seconds with an infrared set-up and determine a good highlight or a strong shadow?
For me that would be like disconnecting your speedometer and determining your speed by licking your hand and using the cool sensation when you hang it out of the window.
We dunk our work at 68 F., not "feels right to me"; we time our exposures, not "that oughtta do it"; we develop good habits and repeat them exactly every time to eliminate unwanted variables. Anything else would be jumping the tracks and off-roading with a locomotive.

OK, development inspectors. Bring it on! :smile:
 

Donald Miller

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Deckled Edge said:
The fascination with development by inspection completely eludes me. I can take two negatives on the light box and study them under a 10x loupe for two minutes, and still cannot decide which will print best with the #2 filter. How can anyone look at a wet negative for a few milliseconds under green light, or a few seconds with an infrared set-up and determine a good highlight or a strong shadow?
For me that would be like disconnecting your speedometer and determining your speed by licking your hand and using the cool sensation when you hang it out of the window.
We dunk our work at 68 F., not "feels right to me"; we time our exposures, not "that oughtta do it"; we develop good habits and repeat them exactly every time to eliminate unwanted variables. Anything else would be jumping the tracks and off-roading with a locomotive.

OK, development inspectors. Bring it on! :smile:

I was fascinated with the romantic notion of doing what Edward Weston did. You have to admit there is a certain mystique to that...something inside said yeah!!! if I do what he did then I undoubtedly will make prints like Edward.

I found out that, in my experience, I can not tell within 15 units the density range of a negative when I have more then a minute in full room light to judge let alone 3-5 seconds under a dim green light. But then maybe it is that my eyes and judgement are fading with my age.

In order to get the most out of the materials we use, I believe that we need to determine the characteristics of those materials and then formulate repeatable procedures to produce results consistant with the characteristics of the materials.

So as a recovering DBI addict. I take it one day at a time and do the same thing over and over again. That means reading negative densities on a densitometer to match the paper.
 
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Sean

Sean

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But I'm not talking about a quick glance in the dark here. I'm talking about full and bright illumination of the negative and looking at it in crystal clarity, in total darkness while it develops. Imagine if you could watch your neg develop on a lightbox in full light from start to finish -this is what infrared inspection can provide. This is totally unchartered territory for me, but if it works, and I can get a feel for this process, the rewards could be pretty phenominal. I also plan to take care during exposure, not just shooting blindly and worrying about it later. I figure I have nothing to loose here. If it doesn't work out I can sell the goggle to a hunter, and the IR lightsource to someone with a B&W security camera or camcorder. Not much risk here in trying something new so I'll give it a shot. I'm not aware of anyone attempting to create a bright 8x10 IR lightbox and deving on a glass tray above that with a goggle, watching the entire process. If anything it will be fun to try :smile:
 

Donald Miller

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Sean, I think that what you are attempting to do is a worthwhile project. My DBI experiences were certainly a lot different then what you are doing. As you said it will be fun. Good luck and I look forward to hearing your experiences.
 

Tom Duffy

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After your eyes adjust to the dark, the green light used in DBI is very bright. The infrared source should not cause you any difficulties.

By the way, the negs and prints I promised you a long time ago are going out tonight. Hope you can still use them!
 

Ed Sukach

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The question here would be the wavelength of the light produced by the LEDs. If it *is* Infra red, greater than ~ 700 nanometers, the Tri-X should be blind to it - or at least it would take a *very* long time to affect it. LEDs, as a rule, are very "monochromatic" I have the JOBO MaxiLux safelight (? - Who pays attention to the names of things?) and that consists of a bunch of LEDs.
Another factor would be the spectral sensitivity during development - I don't know if that would be different from the dry film or not.

Only one way to go - try it. Leave some wet film under it for an extended time, and see what happens.

BTW, was that power supply labeled in the Province of Dyslexia?
 

gainer

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In order for your plan to work, the film will have to be transparent to IR light. Maybe you should check that out before going to a lot of expense. You may wind up having to put the illumination on your side of the film.
 
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