Night lights with an Infrared filter

I have had a lot of fun recently doing night photography. I was intrigued by the prospect of doing the classical car light trails using long exposures with an IR filter (Hoya R72 Infrared). At night, there are of course not many sources of scattered IR light, but I was curious about the results.

Los Angeles freeway traffic capture in Infrared I 

Los Angeles freeway traffic capture in Infrared II 

The images in my Los Angeles gallery on PBase speak for themselves. Interestingly, the results are somewhat soft, probably through diffusion of IR light, compared to the same view seen without the IR filter. This provides an ethereal feel to the image, which I like. I have not tried really long exposures yet (longer than the 30 sec limit of a digital camera), but will soon.

The only challenge with IR photography when using an IR filter in front of the lens is to first prefocus without the filter on, and then make sure that screwing the filter back on does not disturb the lens focus. I used Canon's excellent 85 mm f/1.8 prime lens for this work (58 mm filter size), but any other lens would be fine too. The filters are not inexpensive, so if you are trying this out for the first time, it may be a good idea to rent the filter, or purchase a smaller filter on an appropriate lens.Los Angeles freeway IR photo