Shaking the Sensor
The Nikon D300 has been out for a number of months now; I got mine at the end of last November and couldn't be happier with its overall performance. One of its many new features is a self-cleaning sensor. Here are some thoughts on how well it has worked for me so far.
Technically, what the self-cleaning sensor actually consists of is a self-cleaning filter that lies directly above the sensor. The sensor itself doesn't need cleaning since it can't get dust because it is fully covered by the filter. The cleaning action comes from ultrasonic waves that vibrate the covering low-pass filter at four different frequencies in an attempt to shake any dust lose that may be present. Other manufacturers have built similar systems since dust can be a problem for any camera with interchangeable lenses. Everybody is looking for an answer to the same problem so it's no wonder they try out some of the same ideas.
I can't speak to whether this technique works on other camera but now that I've been shooting for a while with a D300 I can report on my experiences with how well Nikon's implementation works. As I mentioned when I wrote about wet cleaning sensors that have an Indium Tin Oxide (ITO) coating such as on the D300, shaking the sensor won't get everything loose. Pollen grains and stubborn dust particles can sometimes get "fused" to the sensor filter solidly enough that no amount of vibration will do the job. But I have definitely grown to appreciate that more ordinary dust is now less of a problem.
I can remember being down at Mt. Rainier early one morning with an earlier DSLR and discovering a number of spots on all the shots I was taking. I had hiked no more than a mile or so from my car, getting to where I wanted to be in time for sunrise and had made a number of test shots in order to refine my composition before the real magic started. Reviewing them on the camera's LCD back though presented me with a dilemma: ignore the dust spots for the time being and worry about getting rid of them in Photoshop later, or hike back to my car to clean the sensor and risk not getting back in time for sunrise. Needless to say, I was forced into continuing to shoot despite the dust since I almost certainly wouldn't be able to get to the cleaning supplies in my car in time. Yes, I could have cleaned my sensor the night before but I hadn't since I was tired and sunrise comes early during summer. Yes, I could have brought a Rocket blower in my camera bag, but I didn't. Using one on the side of the trail in the dark probably would have been pretty much hit or miss even if I had. But now I have a different option. Just by selecting "Clean Now" from the Setup menu at least some of the dust can be dealt with anytime, anywhere.
When you clean your sensor in this way, you should orient the camera in the normal horizontal position with the camera base down since Nikon engineers provided an adhesive strip to catch any falling dust that won't be in the right place otherwise. Gravity always points down so the adhesive must be underneath the sensor to do its job. If your camera is in any other position the dust that gets dislodged will merely fall in a corner somewhere from where it can move further as you use your camera after cleaning. Eventually, it may fall on that adhesive strip, but it may instead fall back on the filter atop your sensor, right where it started.
To make it even easier, Nikon will let you set the camera to clean the sensor automatically at startup or shutdown. At first this may sound like a good idea, but there's no good way to remember to always hold your camera in the correct sensor cleaning orientation when turning it on or off. Instead, I just added "Clean Image Sensor" to the "My Menu" list. I often do use it when turning the camera on, but only when I know I'm doing it. I'm not sure how much is due to using this option and how much comes from the anti-static ITO coating, but I so far have not had to wet clean my D300 as often as I did with the D2x. Between the built-in sensor cleaning option and an occasional blower bulb when needed the D300 sensor has been pretty good to me. We're only just now getting to peak pollen season in the Northwest of course but hopefully this trend will continue.