It's actually this whole complicated thing. Not really.
Here’s a tutorial of a sort that you may not have come across. It’s a little song-and-dance on the topic of how to clean your DSLR sensor.
Now, granted, this edifying little piece is a few years old, but some things don’t change, and the correct method for wiping a sensor with a lens tissue is one of those things.
Bob Atkins (writing for Photo.net) leaves no hold barred and no stone unturned in this discussion of how (and how not) to clean your DSLR sensor. This guy is eminently qualified to discuss the issue, with a PhD. in chemistry and all manner of other impressive credentials and letters and whatnot. In his tutorial, he talks about how you can tell if the dark spots you’re seeing are dust on the sensor itself, or dust somewhere else, or a personal problem that needs to be resolved in conference with your ophthalmologist. He explains what “DSLR sensor cleaning mode” is—your camera probably has it. He discusses the relative merits of (1) blowing, (2) brushing, and (3) wiping the dust off from the sensor.
Bob also weighs the relative merits of “the commercial solution” and “the software solution.” The commercial solution is that you get somebody else to do the cleaning for you: either the manufacturer, which would involve the annoyance of shipping costs and a week’s delay in being able to use your camera, or a local camera shop or repair center that might charge between 30 and 50 bucks. The software solution, on the other hand, involves a bit of ‘dust deletion” hocus-pocus that your camera may be set up to handle on its own, at least until you find yourself in the position to do a real cleaning.
“What’s the worst that can happen?” asks Bob, echoing the very question that was in your head. Well, you can scratch the sensor: not the ideal outcome, if Bob’s version of things can be believed, because this may necessitate a replacement of the whole sensor assembly, which will in turn necessitate shipping the camera back to the manufacturer for what could amount to several hundred dollars’ worth of repairs. Ouch. (That was our conclusion, not that of Mr. Atkins, though we’re certain that he would concur.)
What we’re saying is this: If you even suspect that you might need to clean your DSLR sensor, you’ll want to have a look at Bob Atkins’s article. You really will.
And now for something completely different…