July 30, 2011
Contour Issues: High Contrast & Snow
If you've got a Contour helmet cam, or if you've ever watched any of my helmet cam videos, like this or this, you've probably noticed that the camera is particularly inept when it comes to dealing with bright, snowy scenes. Highlight detail tends to wash out, leaving obvious and ugly blank, featureless regions of white. The question is: why?
The answer kind of struck me out of the blue (or white) one day, when it suddenly occurred to me that there is almost certainly no variable aperture in the camera. In other words, the only way the camera can adapt to changing light levels is electronically, by varying the sensitivity of its sensor. If that's the case, how would the engineers design the camera so that it could handle a wide range of brightness levels, from sunlight to dusk to dark? The answer is, they would cheat at the ends of the spectrum.
In bright sunlight, the Contour would (theoretically) be designed to operate as close to clipping as possible, so that at the other end of the spectrum, the darks wouldn't get too noisy. So, everything is fine as long as you're shooting in bright sun under normal conditions—ie, grass, trees, and people in your back yard. But what happens when you shoot snow under full sunlight? Well, in terms of EV, this is actually a full stop or more brighter than an ordinary (non-snowy) scene. And it pushes all the highlight detail right out of the camera's range.
Similarly, shooting any highly reflective material when the sun is at the right angle will result in the same phenomenon: the brightness level exceeds the camera's expected maximum. The good news, if I'm right about this, is that there is a pretty easy fix. Just put a neutral density filter in front of the lens to reduce the light entering the camera when you shoot sunny-snowy or otherwise highly reflective scenes.
And yes, I've found an aftermarket kit that allows you to do exactly this (albeit with a polarizer instead of a true ND filter). Will it save those otherwise burnt highlights on bright snowy days? We'll have to wait until next season, as I made this logical leap a little too late to test it this year. But it sure would be nice to get more usable footage out of the Contour when shooting sunny, snowy scenes, wouldn't it? Stay tuned...