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10-26-2012, 11:24 AM   #1
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How does one make the film roll not sensitive to light?

I see that when you first have your film, before you shoot it, you have to be careful not to let it in the light otherwise it'll ruin your roll of film. However when I get my film developed, I see that they give me back my roll of films but this time you can expose it to light. How does one do that? I am going to be developing my film next week in class and am curious as of how this will happen, my professor will of course teach the class how to do it. But I am curious now. Also how does one make that tiny exposure become so big into a print such as a 4 by 6 and such? And when you make the roll of film no longer sensitive to light, it is possible to still use that film to become a big print?

10-26-2012, 11:38 AM   #2
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Well, I'm not an expert, but while the developer changes silver ions to silver oxide (feel free to correct me here), the fixer neutralizes the rest of the emulsion. So to make film non-light-sensitive, just dip it in fixer for about ten minutes.

But this of course removes the film's ability to register images, and if your goal was just to have film that you'll never develop, there's no need to care about exposure at all.
10-26-2012, 11:39 AM   #3
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That's quite a lot of very broad questions. While I could give you some broad responses, I think you just need to hang on and go through all of this step by step in your class with your instructor. All will be revealed. If after that, you have more questions, post 'em here.
10-26-2012, 11:50 AM   #4
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It's Voodoo magic.

10-26-2012, 11:56 AM   #5
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Here is my try at an answer...

QuoteOriginally posted by LeDave Quote
... you can expose it to light. How does one do that?
Simplified: Film starts out as a plastic (usually) backing and a combination of silver or other ingredients are applied and is made light sensitive or getting sensitized, the components are such to allow the chemical reaction to light. This then sets up for later the chemical process to work on these molecules that have reacted to the change. In a form of oxidation they sort of are cooked by the chemical reactions and these bits become the visible grains to make up or represent shades and or colors of the image. When the process of bringing out the image is over, the next thing is to neutralize and wash away the parts that are not to be part of the image which at the same time will make it not sensitive to light. When that is done, all that is left is the "cooked" on gains that is the image.

If you prefer the more tech description... Photographic emulsion - Wikipedia, the free encyclopedia



QuoteOriginally posted by LeDave Quote
Also how does one make that tiny exposure become so big into a print such as a 4 by 6 and such?
This method is done by means of projection. The device commonly is called an Enlarger....

QuoteOriginally posted by LeDave Quote
And when you make the roll of film no longer sensitive to light, it is possible to still use that film to become a big print?
Simply a tray that hold the negative is positioned in front of a light source and a lens to the other side of the negative... in almost the reverse of the taking process... the negative is projected to a sensitized paper that will... reverse the reverse... and render the positive image. The paper goes through a similar process to the film to develop the the image out.


Think of it this way...
So if you start with a black square with a white box in the middle and take a picture of it. The resulting negative produced will be a clear square and a darkened box in the middle. When you project the clear square and darkened box on to a sheet of sensitized paper, the clear part which is allowing the bright light, will sort of excite the sensitized material (exposure) and the darkened box will do next to nothing to the part of that sheet and later you develop that sensitized paper the portion that received the most light will darken from it and the box that received next to nothing will possibly do nothing and remain the same as the paper base.

Last edited by MysteryOnion; 10-26-2012 at 12:09 PM.
10-26-2012, 12:26 PM - 1 Like   #6
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...Ok, First you have to load the exposed film onto a spool, and seal it in a light proof developing tank. Then you pour in a chemical known as developer, and agitate it for a certain period. The time the film spends in the developer determines how contrasty the negatives will be. You then pour out the developer and pour in some stop bath, agitate for one minute, then pour that out. Then you add fixer which remove the remaining silver halide crystals for about 9 minutes. Finally you wash the negatives for 20 or 30 minutes, you may want to add an anti water spotting agent to the final rinse and the take the film off the spool, cut it into strisp, and hang it up to dry. Once it's dry, you are ready to print.

Printing is the step that converts the small negatives into larger positive photos. You use a machine called... an enlarger :P. You put the negative into a film holder, put that in the enlarger and put a light sensitive piece of paper on the enlarger table. You then turn on the enlarger lamp which exposes the paper to the projected negative image. If you're shooting 35mm film you will be able to print up to a certain size before the print would be considered to "lack sharpness", if you're shooting medium format, that size is larger, if you're shooting large format sheet film, the print size can be larger still.

Then you more or less repeat the process you went through to develop the negatives, but this time with the sheet of photo paper you just exposed, and you'll use trays instead of a tank. If you're printing in black and white, you can have a red safe light on so that you can see what you are doing. I've never done color printing myself, but I think that has to be done in total darkness (the red light would ruin the final images).

That's a very simplified overview of the process. There is an art to it all that is becoming lost to modern digital photographers. It used to be that capturing the photo was only half the battle, and the real masters were the ones who could make the magic happen in the dark room.

In truth, I was a little surprised that anyone asked this question, it's just something that I took for granted that all photographers knew. It's amazing how far we've come, but it's a little sad to me that we're beginning to forget our roots. I'm glad that your professor is going to teach you, but how many other photographers out their have no idea how film works?

Here's a very good video on how to develop negatives:

Last edited by maxfield_photo; 10-26-2012 at 12:34 PM.
10-26-2012, 01:11 PM   #7
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With digital you use Lightroom, with film you use Darkroom
10-26-2012, 01:18 PM   #8
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Thanks a ton you guys, also maxfield that video is helpful.

10-26-2012, 02:28 PM   #9
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QuoteOriginally posted by topace Quote
Well, I'm not an expert, but while the developer changes silver ions to silver oxide (feel free to correct me here), the fixer neutralizes the rest of the emulsion. So to make film non-light-sensitive, just dip it in fixer for about ten minutes.
Developer: Silver halide ==> (reduction reaction) ==> Silver metal

Fixer: Residual silver halide ==> soluble silver salts

Wash: Removes all traces of fixer and the soluble silver salts leaving the silver metal (your photo) behind


Steve
10-26-2012, 02:29 PM   #10
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QuoteOriginally posted by maxfield_photo Quote
It's Voodoo magic.
That too...
10-26-2012, 06:11 PM   #11
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My wife always wished I spent as much time in the darkroom as your synopsis implied Maxfield, and not a minute more! Still, good job.

I did it all in B&W, but I was never game to tackle my own E-6 (Ektachrome reversal film) processing. Toward the end of Ektachrome's life, making color prints from slides actually became quite easy. Most of the work happened with full room lights.

You used a spring loaded stage with a dark slide over the paper. The upper surface of the dark slide was equivalent to your glossy photo paper. And when you pulled the dark slide, the spring moved the paper up to the same focus position of the dark slide. The paper was transferred from its box into the stage inside a light-tight bag that had sleeves for your hands. The enlarger had built-in color filtration, but you started with no filtration. Now you turned off the room lights and you projected the slide onto the dark slide, then viewed the image through a hand-held set of colored gels to determine the proper color correction. (or if you were really rich, there were meters to assist with color correction - I was never that rich) Darkroom exposure meters were pretty common by then to determine time. Next you dialed your color correction into the enlarger. All the lights go off, the dark slide was pulled and the enlarger timer tripped to make the exposure. It was possible to do dodge & burn like B&W, but at the possible chance of screwing with your color correction.

The paper then went from the stage into a tube that looked pretty much like a slightly larger version of a film developing tank. And then you could turn on the room lights and process your paper inside the light-tight tube. There were a few more chemical baths and temperature was bit more important, but the activity was otherwise the same as developing B&W film.

And I swear it takes me longer to process and print a digital image on my computer than it did to process an analog image via chemical reactions.

Oh, if you wanted to make small color prints from slides really fast, you used Polaroid SX-70 film cartridges. You used a dummy cartridge for focus and color correction, added some deep neutral density filtration (Polaroid film is understandably MUCH faster than reversal print paper), substituted the real cartridge in the dark, made your exposure, popped the cartridge into your processor (a Polaroid camera!) and snapped a picture with the lens covered. Done!
11-12-2012, 04:39 AM   #12
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QuoteOriginally posted by LeDave Quote
I am going to be developing my film next week in class and am curious as of how this will happen, my professor will of course teach the class how to do it.
How did it go? Welcome to film processing, lots of fun!
another Dave
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