pinhole pictures in high altitude

[Anon Ymous]

I get a plastic infrared filter from Edmund Sci, which works great down here on the ground. Optically plane, it's made of a plastic so hard that I can't score and snap it; it must be cut on the bandsaw. An added advantage is that it is cheap. It doesn't seem to screw up the imagery, either. Even with the Super Angulon. Do you think that any UV could get through that stuff?

Larry

Hello Larry,

IR filters, just like UV, are lowpass filters. The ideal lowpass filter will cut frequencies above a certain threshold. So, since IR is quite lower than UV, it will probably cut out any UV radiation. Of course, you can never be sure about how effective it is, unless you have a look at it's spectral response graph.

But I'm curious. What kind of film will you use with that? Is it an opaque filter, or does it let some red light pass?

[bowzart]

Then it also would not need to be directly on the hole, but keep a little distance, probably also somewhat alleviating the problem with those fuzzy spots.

That will make them smaller, but sharper.

Good luck. I'd like to hear what you discover.

[Lukas Werth]

That will make them smaller, but sharper.

Yup, you are right, of course. Anyway, I will try it without filter, first.