IR with an unmodified Nikon D70

The Digital Imagemaker recently ran an infrared competition (February 2007). All six(6) out of six(6) of my entries made the finals, but I did not win. This confirms my reputation as the Susan Lucci of IR photography but that's neither here nor there. It was an honor just to be nominated. Really.

Bastidges.

Where was I? Oh, yes. From the contest entries I was also struck by the variety of digital cameras people have put into use for IR. DSLRs, compacts, modified and unmodified. I currently use the MOJO EYE, a Sony DSC-F828. But the contest inspired me to take out the Nikon D70 (cute nickname still pending) and give it a go.

Most unmodified digital cameras can make IR images. The ol' TV remote test is a good start. But the most important factor is the strength of the camera's internal hot mirror, or infrared cut filter. Without them most detectors would be overwhelmed by IR light and cameras would not work properly in the visible range.

Slapping an IR-pass filter on the front means it is working against the hot mirror and the necessary exposure time is increased. It's kinda like the Steven Wright joke about buying an humidifier and a dehumidifier, putting them in the same room and letting them fight to the death.

Okay, it's better when he tells it.

The Mojo Eye has a hot mirror that can be removed from the optical path. But most unmodified digital cameras will work only if the IR pass filter lets in more IR light than the hot mirror can block. So it's off to the campus of U. Are Here for some tests with the D70 ...

Straight out of the camera this is unusable. The red channel is overpowering and there are a lot of reflections caused by light leaking through my Cokin P-Series bracket onto the back of the IR filter and into the lens and back again and again.

I blocked off the light leaks and made another image. With no live preview, bracketing and good guessing are mandatory. 1/30 second at f3.5 - not bad actually. Sharpest focus with IR is best done at small apertures, though.

After processing in a photo editor for contrast and color adjustment, this image turned out pretty well. Pretty well, that is, if you go around all day imagining what the Apocalypse would look like. A digital camera's color balance circuitry often reacts this way to being bathed in infrared light. For the classic monochrome IR look, simply desaturate color.

Here's a larger version for your viewing enjoyment. UAH pond, 1440x900