Digital IR Photography
After I picked up my D90 in December I had to consider what to do with my D50. I didn't want it to just collect dust as a "backup" but I didn't want to get rid of it either. I finally decided to take a bit of a radical path: I sent it away to have it converted to an IR camera.
Digital cameras use sensors that are already sensitive to infrared light but internal filters are used so that only the visible spectrum passes. You can simply send your camera away to someone like Jim Chen, however, and he will remove the stock factory filter and replace it with one that only passes IR light. His page has plenty of good information if you are really interested in the technical side of things, as well as LifePixel, another site that does conversions.
I went to Jim and he had the camera back to me very quickly. He was very communicative and helpful and I wouldn't hesitate to do business with him again.
Photographing in a light spectrum that we can't with our naked eye takes some getting used to. Some things look exactly the same while others turn out radically different. Metering becomes a slight issue as your camera will still meter based off of visible light. This is fine if you are shooting in available light that contains IR but if you are under bright fluorescents, for example, you might get dark exposures.
Plants and animals (humans included) can look quite different under IR. For example, our skin looks softer and more porcelain, while our eyes get darker. The dark eyes can be better mitigated with lighting but the below example highlights it to an extreme. The "fake IR" frame is just photoshop channel mixing that some people do to fake IR shots. It works on outdoor photography from time to time but as you can see here, it doesn't come close.
I'm wearing the same shirt in all shots: not only does it reflect IR differently from visible light but shooting IR requires a custom white balance profile in the camera.
And here's what I meant about lighting. The lamp on the right is a "regular" bulb while the bulbs on the left are energy-efficient compact fluorescents.
See why they're so much more energy efficient? The regular bulb is wasting huge amounts of energy in a part of the spectrum that we can't even see.
Converting the IR shots to B+W can give nice contrast
I'm looking forward to experimenting more, especially once plant life is in bloom again. In the mean time I've just been goofing around with it and seeing what I can do.
One fun thing was looking at the IR "signature" of various things around the house. Our military has specifications for certain pieces of gear these days (like uniforms) to reduce their IR signature so they are less observable under night vision equipment. Below is a shot of some camo gear and a nomex flight glove. The camo behaves as expected and gives no IR glow: it remains subdued. The nomex glove lights up brightly, however. The ironic part? The nomex flight glove is actual military surplus issued gear while the camo is aftermarket civilian-manufactured.
For shooting in the dark, I got some IR filter gels that I can put over my flash. They pass almost no visible light so I will be able to photograph at night without disturbing animals/people if I want.
The left frames show the bare flash in (color D90 top, IR D50 bottom). The middle frame is an IR filter that cuts off light below 740nm. When this one is used, you can see a very faint red when the flash fires. Even up close though it's barely noticeable. The frames on the right used an even more aggressive filter on the flash: one that cuts off everything below 780nm. This one has even less of a visual signature when used: you only see a very faint purple which is even less noticeable. It appears to let more light out in the color picture above, but that's only because I wasn't pressing it as close to the flash and light spilled out around it.
Anyway, as you see oddly colored photos, dark eyes and soft skin, or other strange things on my site from time to time, it's because I'm shooting in IR. Hopefully I get some more interesting shots in the near future.