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OT: Know of a way to keep IR out of a cell phone camera?
This thread has 9 replies. Displaying all posts.
Post 1 made on Saturday March 3, 2018 at 14:13
Ernie Gilman
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Many cell phone cameras respond to IR, showing it either as white or as a pale purple. This is great when we want to verify that a remote control is outputting IR.

But I've noticed that photos of sunsets are a lot brighter, and less red, than the visible sunset. And while there's A LOT of red in the sky and the clouds, obviously visible reds are white in the photos. It's as though IR in the sunset is converted to white.

Anybody have some idea if there are IR filters for cell phones? I've looked using google. All I've found is how to do the opposite: filter out visible light to see only IR. I want to filter out the IR so it doesn't influence the photo.

Thanks for any, uh.... light you can shed on this.
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Post 2 made on Saturday March 3, 2018 at 14:20
Glackowitz
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Usually the back camera has an ir filter and the screen side camera doesn’t.
When I test ir from emitters the back camera doesn’t work and only the screen side works, this is on an iPhone 5 and 7.
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OP | Post 3 made on Saturday March 3, 2018 at 15:41
Ernie Gilman
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I should have mentioned that the way these things are named is confusing and inconsistent, so I'm not going to say "IR filter" any more. Note that the thread title doesn't say "IR filter" for just this reason.

I suspect, Glackowitz, that you mean "removes IR light." My Samsung Galaxy S4 sees IR just fine, front and back. My gf's iPhone X doesn't show remote control IR on the front camera, but shows it on the back camera.

This helps us define the confused state of talking about this, but nothing here helps us know how to add an IR-reducing element into the light path. Any ideas?
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 4 made on Saturday March 3, 2018 at 16:55
highfigh
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On March 3, 2018 at 15:41, Ernie Gilman said...
I should have mentioned that the way these things are named is confusing and inconsistent, so I'm not going to say "IR filter" any more. Note that the thread title doesn't say "IR filter" for just this reason.

I suspect, Glackowitz, that you mean "removes IR light." My Samsung Galaxy S4 sees IR just fine, front and back. My gf's iPhone X doesn't show remote control IR on the front camera, but shows it on the back camera.

This helps us define the confused state of talking about this, but nothing here helps us know how to add an IR-reducing element into the light path. Any ideas?

Well, apparently, the front lens DOES filter IR out, but you need to block UV, too. Look for a UV filter and you may find what you need. It may be called a 'skylight' or 'neutral density' filter.

You should remember- photos of objects only show the reflected light and cameras aren't designed to photograph the Sun without some kind of filtering, generally UV (as I wrote before). Photographing the Sun is nothing like getting images of things and people- the light is far more intense and that not only affects the colors, it affects the exposure.

Are you mainly using her phone for these photos, or yours, too? If you use yours, what is it?
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Post 5 made on Saturday March 3, 2018 at 17:43
Fins
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There are several companies that make clip on lenses for phones. Usually they are telephoto or wide angle add ons. I’ve seen one that was adjustable. It makes sense that someone makes one with filters


Edit: also, what you may really need is a polarized filter. This is a common one in photography to reduce or prevent glares.
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Post 6 made on Saturday March 3, 2018 at 17:47
Mac Burks (39)
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You could always try buying a camera and quit trying to use your phone as a camera.
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Post 7 made on Saturday March 3, 2018 at 19:04
Fins
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On March 3, 2018 at 17:47, Mac Burks (39) said...
You could always try buying a camera and quit trying to use your phone as a camera.

Are you saying Mr Details is using the wrong tool for the job?
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OP | Post 8 made on Saturday March 3, 2018 at 21:50
Ernie Gilman
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On March 3, 2018 at 17:43, Fins said...
Edit: also, what you may really need is a polarized filter. This is a common one in photography to reduce or prevent glares.

From [Link: digital-photo-secrets.com]:
When the sun strikes a reflective object at angle, it can sometimes cause the light to reflect into your camera. If you break this down, it means there are two causes of glare. The angle of the sun causes it and so does the presence of reflective objects.

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.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 9 made on Sunday March 4, 2018 at 09:04
Fins
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Btw, everything I found says the S4 has IR filters. There are multiple videos on how to remove those filters to get night vision photos
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Post 10 made on Sunday March 4, 2018 at 09:31
highfigh
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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.
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."


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