Digital IR - Nikon D80
In January 2007, I upgraded my infrared converted Nikon D70 to a new Nikon D80, which I converted to infrared by Lifepixel, in the USA. I shifted to the new camera for two reasons - first, my Nikon D70had worn out one shutter (after making 67,000 images), and second, the new D80 has an RGB histogram, which will make exposing with the converted camera more accurate. Ironically, the main reason most people upgrade cameras (more resolution) isn’t much of a factor with my work, because of how I use advanced digital techniques - stitching and exposure blending.
A few weeks later, I bought a Nikon D200 camera, and have since come to realize I should have waited a little longer until I could have afforded two D200s and converted one to IR. The D200 is such a nice camera, and makes the D80 feel quite inferior in comparison (though the image quality of both is near identical, the photographic experience with the D200 is way ahead of that of the D80).
When the D80 came back from conversion, it was immediately evident how much of an improvement it provided over the infrared converted D70. The additional resolution was actually quite apparent, and as much as I didn’t think it would be part of the reason to get the camera, it ended up providing a major improvement over the previous one.
Focus Correction
When I received the modified D80 back from Lifepixel, I immediately set it up and made an image. Right away, I was impressed with the larger screen, and more importantly, the RGB histogram.
As I suspected however, while the autofocus was close, some modifications was necessary before the camera provided perfect AF accuracy with a 50mm f/1.4. Lifepixel clearly states they calibrate the camera to be accurate with the 18-55mm lens, which I don’t have, so I had expected this issue. After a quick application of the same technique used to correct the focus of the Nikon D70, the camera worked exactly as I’d hoped.
Field Experiences
Working with the IR converted D80 is a serious improvement over the D70 (which I loved at the time). The RGB histogram make it much easier to get a good exposure (as opposed to the luminance histogram on the D70).
I was quite surprised by how much difference the 10mp (vs. the 6mp I had used before) made, with more detail and clarity when the images are infocus, and more silky-smooth out-of-focus tones when they aren’t. This was, as I said, not the primary reason I shifted to the D80, but I am pleasantly surprised at how much it contributes to the final images.
The only continuing issue with the IR camera is the focus. While the camera is carefully adjusted to provide accurate focus with my 50mm f/1.4 portrait lens, I have (after 30,000+ images) learned that even this is limited. The AF accuracy is optimized for portrait, and becomes quite inaccurate (at f/1.4) beyond 10’, being totally out of focus at the horizon.
These issues (AF accuracy varying depending on focus distance) become even more difficult with other lenses. My 10-20mm Sigma lens needs to be focused beyond infinity to be focused at 20’ or so, and can’t actually focus on infinity. In order to get the horizon in focus, I have to rely upon depth of field (stopping down to f/11) as opposed to actual focusing. The technique I use to overcome these issues is focus bracketing - I make a series of images gradually focusing from as far beyond infinity as I can go, to the point where the image looks significantly short focused. This usually takes 4-5 frames, and explains how I can put 30K images on a camera in 10 months!
