@rockb wrote:
The option "Sensor Clean" is not listed in the menu (Neither are Custom Functions or Clear settings
Ah, a 20D. I had a couple 30D and had to clean their sensors fairly often (3 or 4 times a year), shooting a lot in dusty conditions.
Starting with 40D Canon has put "self-cleaning" sensors in their cameras. When you power the camera up, it runs a quick "ultrasonic" sensor vibration that "shakes" off dust. There's a slightly sticky strip alongside the sensor to "trap" specks of dust shaken off the sensor. That and improved coatings that reduce the ability of dust to adhere make the later models less prone to sensor dust problems But even they need cleaning occasionally.
I use cleaning methods such as are outlined at the link I provided above: bulb blower, wet cleaning, dry cleaning (brush & slighlty adhesive "lift off" tools), etc. A lighted magnifying loupe is very helpful, doing this. AVOID LIKE THE PLAGUE using canned air or common cotton swabs inside any camera. Canned air is too strong a blast and can blow liquid propellant onto the sensor. Common cotton swabs (Q-tips) shed tiny, tough fibers that can get into and jam mechanisms such as a camera's shutter, resulting in costly repairs.
You will find a "sensor cleaning" mode in your 20D's menu. First you need a fully charged battery in the camera in order to be sure the camera will stay in this mode long enough to do the cleaning. You don't want it shutting down mid-cleaning, risking the shutter closing onto any cleaning tool you're using.
If the camera has never had its sensor cleaned, it almost certainly will need a "wet cleaning" to remove adhered dust and oils from the sensor. Ebiggs is 100% correct... You actually are cleaning a filter that sits directly in front of the sensor itself and this cleaning must be done properly with the right tools. If you are at all uncertain of your skill and abilities doing it, might be better left to a pro at a camera shop. Read everything at the above link and decide if you want to invest in the proper tools and learn to do the cleanings yourself, at your own risk... Or if you would be better taking it to a shop or sending the camera to Canon Service Dept. and paying a bit for them to clean it. (Without the cost of shipping, if needed, a single, simple, professional cleaning usually costs about 1/3 to1/4 what it would cost to buy the tools and supplies to do it yourself. In other words, after having it cleaned professionally 3 or 4 times, in terms of cost alone you might have been better off buying the stuff and learning to do it yourself.)
After cleaning use common sense... Change lenses in as dust free conditions as possible. And when lenses are off the camera, keep the rear lens cap and camera body caps on. Keep those clean, too.
Finally, any specks of dust seen through your camera's viewfinder are just on the mirror or the focus screen, and will not show up in your images (at the instant of exposure the mirror is momentarily lifted, covering the focus screen, before the shutter opens). There's some very slight chance that dust on mirror or focus screen might migrate around and eventually find it's way past the shutter onto the sensor. But it's mostly just a minor nuisance so you should never try cleaning the mirror or focus screen yourself, with anything more agressive than a puff of air from a bulb blower. Both the mirror and the focus screen are easily damaged. So leave any more intensive cleaning of those to the pros, to avoid costly repairs.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM
