Posted by Deliverator on April 29th, 2009
One of the few real downsides to digital SLR cameras versus their film brethren is getting dust on the sensor. With a film camera, each new exposure yields a fresh “sensor,” but over time with a digital SLR, dust which gets into the camera frame during lens swaps can coat the sensor (technically the IR filter over the actual sensor). At larger lens apertures, dust on the sensor generally can’t be seen, but at small apertures against a fairly consistent bright background, you can really see it. I shoot a fair number of panoramas with my Nikon D80 and often see repeated spot patterns on the source images. One can clean these sorts of problems up in Photoshop, but it greatly increases the amount of time spent in post-processing.
For most cases of dust on the sensor, I have simply used the mirror lockup mode on my camera to reveal the sensor and then used an oversize rubber air bulb to blow the dust off the sensor. Mine is this one made by Giottos, but these are a dime a dozen. It does the job most of the time with a minimum expenditure of effort.
Recently, I encountered some dust that had “welded” itself to the sensor and wouldn’t come off with any of the above methods. Welded dust is probably usually the result of some sort of particle that is wet when it makes contact and dries hard to the sensor. To get it off, you need to use a “wet” cleaning method. The favored method seems to be a few drops of Methanol on a very fine cloth attached to the end of what amounts to a miniature squeegee the width of your particular cameras sensor. A number of companies sell wet cleaning kits. I got one from Photographic Solutions for $20 for 4 pre-wetted swabs. I was hoping that just one swab would be enough and I could keep the others in my camera bag for emergency in-the-field use. I ended up needing to use all four swabs in the kit to get the majority of welded dust off my sensor. Is this a good value? I would probably buy my swabs and Methanol separate in the future. On the other hand, the cheapest wet cleaning I found in the Seattle area was at Cameras West for ~$60
Here are some before and after pics to show the difference. The pictures were taken at f/16 and are of a relatively undifferentiated target (my projector’s screen).