Color Theory Question

[bonsor]

This is my first post here, so I am not quite sure if I am posting this in the right forum, so mods feel free to move it if it's in the wrong place.

Anyway...

I know that inaudible sound frequencies will affect the way audible frequencies sound to the listener, because of the way they interact with eachother. I was just curious if the case was similar with lightwaves, as in...will ultraviolet or infrared light reflecting off an object affect the color's appearance, or is it a totally different concept?

Thanks! :)

[PhotosGuy]

If you're asking about interference effects, it probably is happening to some extent but I doubt that the tiny interference effects can be measured by our media, film & sensors, to the point that we'd notice them. Much more noticable would be the UV & IR effects themselves. So, "Ultraviolet or infrared light reflecting off an object" may "affect the color's appearance" which is why we use a UV filter at times & some films are designed to be more sensitive in those wave lengths. OTOH, all my Physics is undergrad, so maybe someone else would have a different take on it.

[robertwgross]

About the only thing that I detect from ultraviolet light is the sunburn afterward.

In the old, old days, the electric eye metering in cameras was calibrated to be roughly correct at sea level. If you went to some high altitude where UV light is three times as strong, then the calibration was way off. The meter would detect too much light (skewed by UV) and then your photo would be underexposed. So, serious UV filters were necessary for high altitude work then.

Now, I believe that most modern digital sensors have a UV filter in contact with them, so I don't think there is so much calibration problem.

---Bob Gross---

[Longwatcher]

The answer depends on the sensor in question and its spectral response (something I can never get out of Canon when I ask)

The CMOS sensor used on the Canon DSLRs seems to start its response at just above UV, which is why no significant effect of UV filter on effects. It could be a filter in place over the sensor, but I thought I read that the CMOS sensor are just not sensitive in that region.

The sensor itself is apparently very receptive to near IR region, which is why Canon puts a filter in front of the sensor which restricts the ability to do IR (except 20Da). Some of the filters let some IR in (although not much), so we can do IR with some of the cameras. Since a small amount if IR can get to the sensor, it will affect the color of the final image a very small amount, but at shutter speeds faster then 1/2 sec you are highly unlikely to notice the difference. On the 10D/300D sensor it appears to be around 2 secs, that it will start making a slight difference, although still minor compared to the RGB effects (like 2 IR photons out of 2000 red). With a IR filter (like Hoya R72) this restricts the visible light and lets a higher relative percentage of IR light through to the sensor so you start seeing near IR effects.
My understanding is the 20D/350D sensor is similiar, but the D60 sensor had a stronger IR blocking filter on it. My 1DsMkII appears to let more IR farther out in then closer in IR then the 10D I have, so the filter seems to allow for slightly better IR. Could be imagination or just manufacture variations though. Also note that the focus point for IR is different then for RGB so the appearance will also be lessened because of this.

Short answer is IR could affect longer duration shots, but is not likely to affect short duration shots if at all. UV has no apparent affect on the sensor as far as I have been able to determine.

Just my memory, research and opinion,