On March 3, 2018 at 21:50, Ernie Gilman said...
From
[Link: digital-photo-secrets.com]:
What they don't mention is that reflections do not include all angles of polarization of light. A polarizing filter can attenuate the polarized light that is glare.
But I'm not talking about correcting for glare. I'm talking about a portion of the spectrum being presented as a different portion of the spectrum: IR appears as white, blowing out subtle sunset colors.
I can't think of a good sonic analogy, so here's a bad one: You've got a hifi system and it performs really well. That's the camera not allowing IR to influence the image.
But an audio system that would take, say, all frequencies below 100 Hz, convert them to some scale that's non-harmonically related to the original frequencies, and mix them in... that's the cell phone camera showing IR as white or purplish. That is, all of the original image is there (as was all of the music) but there's ALSO some stuff in the original frequency spectrum that wasn't there before it went through the system.
What I'm saying is that high levels of IR exist in sunset lighting and in lighting where a lot of heat is generated, and I want to keep that IR from affecting the photograph. I don't see that IR at all, and if my camera sees it as white, I won't be able to get a photograph of what I see.
The audio analogue is low frequencies making the sound muddy- IR is low frequency light.
If you don't know much about photography, look in some of the online photographic sites, specifically the kind that deal with what you're trying to do. Outdoor Photography and their sister publication that dealt with digital are good choices, as well as Shutterbug magazine.
This might help-
[Link: practicalphotographytips.com]Our eyes are very limited in bandwidth- no IR or UV is visible to us and that makes photography frustrating- it doesn't matter what format or medium, it won't look the same as how we see it.
You need to filter the IR AND UV if you want it to translate better, but you really should think about using an actual camera for this. You'll have better control of what it records and you can adjust the color gamut, effective exposure and some will let you decide what is filtered out of the picture. Lots of good cameras are out there and if you don't want to spend a lot, go to a local camera store and ask about their trade-ins. They should be able to answer your questions about using a phones camera, too.
