A Quick and Dirty IR Workflow

I had some reading to do today and so I walked down to the park and set up the camera for a 45-minute exposure. Up until now, I've been shooting out of my office window and the composition isn't exactly a Minor White. After a few 45-second test shots at f/4.0 and ISO 3200, I set the remote for 45 minutes and the camera for ISO 50. It's convenient that seconds at ISO 3200 are about the same as minutes at ISO 50. The same is true for ISO 6400 and ISO 100, which makes a nice rule of thumb. Before pressing start on the remote, I attached the lens hood, tied my floppy sun hat over the viewfinder, and hung my backpack from the tripod. The sun would be shining on the filter for the next 45 minutes, so the lens hood wouldn't be any help, but the hat kept light from leaking in through the viewfinder and onto the sensor, which has been a very repeatable problem in the past. The backpack was used to stabilize the tripod on an already breezy day. With all of that in place, I hit start and sat down to read.

Exactly 45 minutes later, I packed everything up, leaving the camera on and the viewfinder covered for the ensuing 45-minute dark image, and headed home. I left the camera outside while it collected the dark image because the air conditioner was on and I would expect the hot-pixel signature to change with temperature. Once again, I sat down to read. Another 45 minutes later, I brought the camera in and imported the image into Lightroom 2.4. I set the color temperature to 2000 and the tint to -130, which are values that have worked well in the past for what we're about to do, and adjusted the exposure, brightness, contrast, and etc. as usual. When I had a pretty good looking image, I shipped the results over to Photoshop CS3, switched the red and blue channels using the channel mixer, and added a warming filter (85) at 45%. None of these steps are required, of course, but the false color image that results has a deep blue sky and warm highlights, which may be appropriate for some compositions.

In the end, the image was just off from tack-sharp, but the clouds cooperated beautifully, the camera stayed put, there was no viewfinder leakage, and the sun on the filter didn't do a thing. I attribute the softness to the f/4.0 aperture and so I imagine I'll move right back to a very comfortable f/11 when the Hoya R72 arrives.