16x20 and film options

Dr Croubie said:

So here's a question, with double-sided X-Ray film, does the emulsion on one side (facing the lens), completely block any light from getting through to the other side? Or can you get a bit of light through one emulsion to the other side similar to shooting Redscale.

I'm having devious thoughts for a very cool project, shoot nice landscapes on one side, then if the other side emulsion is completely intact, reload it around the other way and overlay something over the other side for some ghostly double-exposures.

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StoneNYC said:

It goes straight through, in fact I can't ever tell which side was the side that got hit "first"

It's designed like this on purpose....

The idea of having two sides of emulsion for x-ray film is that the amount of x-ray that is needed to penetrate the film becomes cut in half by having a double emotion making the image density doubled, this means that less x-rays are being used on the human body and therefore it makes machine safer for people.

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MattKing said:

Actually ......

X-ray film isn't really very sensitive to X-rays. Most of the X-ray just travels through it. It is fairly sensitive to visible light.

The X-ray film is exposed in machines that have fluorescent screens behind the film. Those screens are sensitive to X-rays - they absorb those X-rays and then re-emit visible radiation back on to the film in front, in a pattern that matches the pattern of the original X-ray source.

So the resulting film has a faint image (created directly by the X-rays) on the front, and a much stronger image on the back, created by the emissions from the fluorescent screen behind.

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