Digital cameras' I.R. Range?

[Soapy Sam]

Lacking any dedicated IR sources in my home, I just tried photographing several heat sources at low temperature (ie not glowing visibly), to see if I could detect any IR related anomaly. Nothing at all.

Has anyone got any hard data , or photos of IR sources interfering with digital cameras?

Call me a sceptic, but...I'm skeptical.

[Pragmatist]

Originally posted by Soapy Sam
Lacking any dedicated IR sources in my home, I just tried photographing several heat sources at low temperature (ie not glowing visibly), to see if I could detect any IR related anomaly. Nothing at all.

Has anyone got any hard data , or photos of IR sources interfering with digital cameras?

Call me a sceptic, but...I'm skeptical.

That probably won't work because the IR you are looking at is likely in a totally different range to that of the camera sensitivity. IR covers an extremely wide range of frequencies - much more than the visible spectrum of light. Body temperature peaks at a wavelength of around 9 microns (that's 9000 nm) and infra red starts around 700 nm. Which means that anything hotter than body temperature will have a shorter (peak) wavelength than 9000 nm and the temperature will have to increase a lot to bring that up to the start of the visual range (i.e. 700 nm) - around 3900 degrees Celsius. The CCD's used in digital cameras are typically sensitive down to 1000 nm or so, but the way the camera works is that special filters are placed over individual cells of the CCD to give colour rendition - the filter will modify the response and so a camera with a more restrictive filter will remove more IR than one with less - it varies from camera to camera.

The infra red emitters used in remote control and the like vary depending on which LED is used - but 975 nm is a typical frquency for IR remotes. Which is the equivalent to peak radiation from a heat source at 2700 degrees C approximately! So unless you happen to be looking into a blast furnace it's unlikely you'll find the equivalent radiation intensity of a typical IR remote in common environmental sources.

I haven't noticed the effect myself but it doesn't sound implausible to me.

[Soapy Sam]

Thanks for that Pragmatist. I didn't actually expect to see anything, as I have never seen any effect from heat sources in photos to date, but it was simple to check before opening my mouth.
There's a building nearby with IR security lights. I will try photographing those this evening. (Probably end in jail).

Has anyone tried the experiment with an IR source such as a computer or remote control?
I would be interested to see what effect if any is created.

[mummymonkey]

Originally posted by Soapy Sam
Has anyone tried the experiment with an IR source such as a computer or remote control?
I would be interested to see what effect if any is created. I looked at my Sky remote with a digital camera and you can see the IR source blinking on and off via the camera's preview screen.

[Soapy Sam]

And you can't see it with the naked eye?
What colour does it appear?

[Pragmatist]

Originally posted by Soapy Sam
Thanks for that Pragmatist. I didn't actually expect to see anything, as I have never seen any effect from heat sources in photos to date, but it was simple to check before opening my mouth.
There's a building nearby with IR security lights. I will try photographing those this evening. (Probably end in jail).

Has anyone tried the experiment with an IR source such as a computer or remote control?
I would be interested to see what effect if any is created.

That should certainly be interesting to explain to the police, "Yes officer I was hanging around at night, photographing the security installation because I'm a skeptic and I don't believe that IR shows up on digital cameras without evidence." :D

I just tried mummymonkey's remote experiment with my Casio EXP-600 digital camera and sure enough it works. I tried a whole range of different controls (O.K. I'm a gadget freak! :D) and sure enough all the controls I looked at showed up on the camera's preview screen - but were not visible to the naked eye - except one which looked faintly red to me. On the preview screen they showed up light blue (most of them) and the reddish one appeared violet on the camera screen.

[mummymonkey]

Originally posted by Soapy Sam
And you can't see it with the naked eye?No.

What colour does it appear? Looked white to me.

[CodeComplete]

While on the subject of CCDs receiving infra-red...

Howabout a cheap and cheerful do-it-yourself infra red webcam? Now you can add infra-red detection to your PC home security system:

http://homepage.ntlworld.com/geoff.johnson2/IR/

[Darat]

Originally posted by Soapy Sam
And you can't see it with the naked eye?
What colour does it appear?

Have a look here:http://www.remotecentral.com/features/infrared.htm

Plus this is from my ProntoPro taken with my Sony DSC-P120. Couldn't see anything with the naked eye, appeared pinkish on the camera screen and more purple/lilac in the file.
http://www.darat.org/JREFPhotos/remote.JPG

[Kopji]

IR focuses on a different plane than visible light so it would look blurry unless you compensated somehow. A good 35mm camera would probably be a better device to capture IR than digital. Some zoom lenses also have focusing marks for IR (a curved red line on the barrel).

A problem with digital cameras is unless you have a really good one there is going to be a lot of ccd noise at low light or high ISO.

[jmercer]

If you're really interested in IR viewing through your camera, try here (http://www.fjwopticalsystems.com/page2.html) or here. (http://www.electrophysics.com/)

[alfaniner]

Originally posted by Darat
Have a look here: ...

Plus this is from my ProntoPro taken with my Sony DSC-P120. Couldn't see anything with the naked eye, appeared pinkish on the camera screen and more purple/lilac in the file.
[IMG]

Isn't that Rutherford B. Hayes in the first circle?

http://www.whitehouse.gov/history/presidents/images/ca21.gif

[IIRichard]

Originally posted by CodeComplete
While on the subject of CCDs receiving infra-red...

Howabout a cheap and cheerful do-it-yourself infra red webcam? Now you can add infra-red detection to your PC home security system:

http://homepage.ntlworld.com/geoff.johnson2/IR/

Either slashdot or boingboing had an article on this. Basicly one uses an exposed negative (black) to block the visible while letting IR in to the lens.

[LTC8K6]

I tried several remote controls with several different digital cameras. All of the remote's IR signals were clearly visible with all of the cameras.

[Soapy Sam]

I never did check that security camera. Rain stopped play.
I'll be home next week and will try then.