I was looking at old photographs of the nuclear tests on the bikini atoll. It da

Question

I was looking at old photographs of the nuclear tests on the bikini atoll. It dawned on me that you don't want to run film through airport x-rays, as it exposes the film. I've been told that a nuclear explosion emits all energy on the spectrum (IR to Gamma). If this includes x-rays, why wasn't the film ruined? Is it because:

1) I'm an amateur radio operator. One of the things I'm familiar with is that RF signal strength starts at a point, and changes by a sum of squares (correct me if I'm wrong PLEASE!) as you move away from the point. If all energy behaves similarly in this respect, is this just a, "not enough x-rays at this distance to effect the film discernibly?"

2) The body of the camera must be taken into account (maybe?). Most cameras of this time period were metal (I believe). Most of the film curtains/iris' we're made of metal too. The only point of entry might have been during exposure?

3) A combination of 1+2

4) Some other awesome physics thing that I can't wait to learn about?

5) Pics of nuclear blasts are all photoshopped productions (I'm kidding of course)?

Explanation / Answer

I believe most of the em-spectrum from a nuke is low energy. So when you take a photo you get a lot of visible light and heat, and only small amounts of high energy radiation on your film. Also the lens might be transparent to visible light, but non transparent to high-energy em-waves.
It says that most of the inital photons are indeed in the X-ray spectrum, but these high energy photons are quickly absorbed by the atmosphere. So the spectrum reaching the photographer is determined by the atmosphere transparency.

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