|DIGITAL INFRARED PHOTOGRAPHY|
*UPDATE* May 21, 2007: I've just uploaded a review of a Canon 20D digital SLR modified by LifePixel for infrared use. --
One day during the Spring of 1998, I pointed my Agfa ePhoto 1280 at an infrared remote control and noticed that it could see the light coming from the infrared LED. I went out to a local photo store and bought a (relatively inexpensive) Kodak Wratten #87 gelatin filter and a Nikon AF-1 Gelatine Filter Holder, mounted it on the Agfa, and took a photo of my hand illuminated by a 50 watt halogen lamp. The results were dark. At first, I thought the experiment had failed, but auto-leveling (SHIFT-CTRL-L) in Photoshop revealed to me that it had, in fact, worked! The next morning I ran outside and snapped a shot of the trees outside of Rains (graduate apartments at Stanford).
I guess I shouldn't have been surprised that consumer digital cameras could effectively capture near infrared images. CCDs had been used in security cameras long before consumer digital cameras started using them, and are roughly as sensitive to near infrared as they are to visible light (when unfiltered). Consumer digital cameras use hot mirror filters to filter out infrared light, but some infrared light gets through, which is what we're interested in capturing.
The various consumer digital cameras have hot mirror filters of varying effectiveness. I found that the Nikon Coolpix 950 was capable of producing high quality infrared images when used in conjunction with #87 and #87C filters. When the Nikon Coolpix 990 was released, it was discovered that Nikon (or the CCD supplier) had improved the hot mirror filters in the camera, necessiting the use of different filters to effectively capture infrared light (#88A or #89B filters).
Some interesting charts:
I've gotten hundreds of emails asking whether a digital camera of brand x is capable of capturing infrared light. While I can say conclusively that most Nikon, Sony, Olympus, and Canon cameras are capable of capturing infrared images, I can only write about what I have direct experience with. Try it! You can find out whether your camera can capture infrared light by testing to see if you can capture (in the LCD of your digicam) an infrared remote's LED lighting up when you press buttons on it. If you can see the LED light up, you'll have to find the correct filter for your camera that will let in the proper wavelengths of near infrared light. You must not let any visible light enter the lens of the camera, because it will likely overpower the small amount of infrared light that gets through the camera's hot mirror filter.
Most recently, I've noticed (from people emailing me) that older 2.1 megapixel cameras will capture infrared light well with #87, #87C, and R72 (87B) filters, and newer 3.3+ megapixel cameras work well with #88A and #89B filters. While this is by no means a conclusive statement, it's a good place to start. :)
These days, I use a modified Nikon Coolpix 990 that has had its hot-mirror filter removed and replaced by glass with similar optical qualities (thanks to Gary Traveis for the modification!). Please do not ask me where to obtain such pieces of glass, or how to modify your camera. James Wooten has a page (mirrored here) that details hot-mirror removal processes. A modified Coolpix 990 can shoot at shutter-speeds in excess of 1/100 sec at f4.4 in full sunlight, at ISO 100. It's very nice. :)
For more information, try the following links (please read the FAQ and tutorial before emailing me with questions!):
- Infrared Canon 20D Review : Modified Infrared SLR by LifePixel [new]
- Near Infrared Image Gallery 2004/01 : Random Shots
- Near Infrared Image Gallery 2003/07: New York and Miami Beach
- Digital Infrared Faq (v1.0.1, 2000/10/17)
- Digital Infrared Photography Tutorial
Agfa ePhoto 1280 w/filter holder attached:
Nikon Coolpix 950 w/filter holder and filters attached, with and without hood: