Is there such thing as a digital infrared camera? and how...

[ismael]

Hello,

I was wondering, since I was looking at some thermal photos from infrared film. Is there such thing as a digital infrared camera? Is that film still available? How do you use infrared film? I think the camera meter will not help much. Just curious.

Thanks,
Ismael

 

[ksmattfish]

I was wondering, since I was looking at some thermal photos from infrared film. Is there such thing as a digital infrared camera? Is that film still available? How do you use infrared film? I think the camera meter will not help much.

IR photography takes place just a hair's width outside the visible spectrum (on the red side of ROYGBIV). IR film is designed to be more sensitive to that end of the spectrum. Many digital cameras are also sensitive to the IR part of the spectrum. To get maximum IR effect in a photo you need to block some or all of the visual spectrum; this is usually done with a red filter.

There are several manufacturers that still produce IR film. It was originally designed for scientific studies (for instance it's easy to determine ground cover from the air with IR photography). As far as results from digital cameras, check the web, there are lots of photogs doing it. They'll be able to recommend the cameras it works best with. The camera will need some way to mount a filter onto the lens. Some manufacturers place an internal filter to block IR, beause it can affect image quality. If you are interested in digital IR photography don't get one of these cameras.

Normal light meters usually don't work well for measuring IR. IR doesn't bounce around like UV, so your subject matter must be directly exposed to the IR source. The best IR source is the sun. IR cuts through the atmosphere, so when the sun is low in the sky, and it seems like there is less light, there is lots of IR. On the flip side, shooting in hazy conditions with IR significantly reduces the apperance of haze in the photos. Many artificial light sources also output IR as well as visible light, including most electronic flashes. Experience is the only way to learn how to shoot IR; you will notice that the instructions that come with the film are vague. You'll have to practice.

I don't exactly know what you mean by "thermal photo", but IR photography does not expose from heat; it requires a source of IR light. The only way the heat of a subject can affet the photo is if the temperature of the subject affects it's IR reflectivity. While there are motion cameras that register subject heat (as seen in many Hollywood movies), this is not what is going on with IR photography. For instance, if you try to shoot a pic of a hot car engine at night with IR film you will get nothing. The film/digital sensor requires an IR light source.

Check out the Alternative Processes section for more info.

 

[ismael]

Thanks fore the reply. Then what I saw was a thermal image and not an IR image. It was part of a HVAC study on a building, and it showed which windows and doors were "leaking" heat so the insulation can be verified. Heat produces IR, but lower in the frequency spectrum. What I understand from your reply is that IR film actually covers the visible spectrum with more weight towards the red, covering some of the IR. Interesting.
Thanks!

Ismael