Infrared eyesight

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Peter Jonasson - 26 Dec 2004 00:47 GMT

Can cats see in the infrared spectrum??
I'm thinking of putting a camera and an IR-light in an enclosed area where
Felix often hides but I don't want to put a (for him) visible light right in
he's eyes.

Regards Peter

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Mike Rhino - 26 Dec 2004 01:49 GMT

> Can cats see in the infrared spectrum??
> I'm thinking of putting a camera and an IR-light in an enclosed area where
> Felix often hides but I don't want to put a (for him) visible light right in
> he's eyes.

Can cats see red? Some zoos use red lights in their night section, because
some animals can't see it. Maybe that makes it sound like the red light
district. I doubt that cats can see infrared.

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Ted Davis - 26 Dec 2004 02:23 GMT

>Can cats see in the infrared spectrum??
>I'm thinking of putting a camera and an IR-light in an enclosed area where
>Felix often hides but I don't want to put a (for him) visible light right in
>he's eyes.

Define "IR-light" and "camera" - both terms cover extremely wide
ranges of meanings (and costs and difficulties).

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T.E.D. (tdavis@gearbox.maem.umr.edu)

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Ted Davis - 26 Dec 2004 15:40 GMT

>>Can cats see in the infrared spectrum??
>>I'm thinking of putting a camera and an IR-light in an enclosed area where
[quoted text clipped - 3 lines]
>Define "IR-light" and "camera" - both terms cover extremely wide
>ranges of meanings (and costs and difficulties).

From e-mail:

>A simple webcam and some infrared LED-s, dont know the exact spectrum for those but I can check that up.

That may work. Many cheaper CCD cameras are sensitive to infrared and
do not have the infrared rejection filter one would expect in high
quality equipment (infrared sensitivity is *not* desirable in visible
light work). In addition, the small size of the sensor and short
focal length of the lens make focusing for infrared (different from
focus for visible light) a non-issue. However, most webcams are
tricolor and have fairly narrow band filters over the cells -
obviously the green and blue cells will be blank and the red ones may
or may not be IR sensitive. You really need a B/W camera instead of a
color one.

I might mention that inexpensive video cameras with built-in infrared
LED illuminators are sometimes available on the surplus market - they
are intended for security camera use.

I would not expect any problem from/for the cat unless the LEDs are
too close to the visible range, too bright, and too close to the cat.
I would expect the described setup to work poorly, if at all.

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T.E.D. (tdavis@gearbox.maem.umr.edu)

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Peter Jonasson - 26 Dec 2004 22:50 GMT

>>>Can cats see in the infrared spectrum??
>>>I'm thinking of putting a camera and an IR-light in an enclosed area
[quoted text clipped - 28 lines]
> too close to the visible range, too bright, and too close to the cat.
> I would expect the described setup to work poorly, if at all.

OK I think you might be right, I came up with the idea when I found out the
camera in my cellphone easily could detect the light from the TV remote
control but now when I tested with my webcam, that wasn't at all as good (a
strange remark is that the light in the cellphone actually looks white!
[poor color filter no doubt]).
But!! I have a friend that have a webcam with an IR light that works very
well, but that's probably intended for just that purpose! I will ask him
what stuff he has bought!

Regards Peter

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