BOTTOM LINE: For $22, you get a no-touch system to take care of 90% of all your sensor cleaning. Go to www.americanrecorder.com/catalog/default.php?cPath=10 to purchase it. Doing it yourself also requires around 10 minutes of your time. Removing more stubborn dirt from really filthy sensors takes $50.45 for Photographic Solutions' Eclipse solution and sensor swabs. Go to www.bhphotovideo.com to get 'em. It may take up to 20 minutes of swabbing and checking to clean completely - but you want clean images without spending time in Photoshop to get 'em.

Light touchup for easy dirt: Giottos Rocket Air Blaster is a large blower bulb providing an air stream with enough force to clean a sensor, unlike wimpy small blowers. Available at Adorama for $9.95. www.adorama.com/GTRAB.html

A big blower bulb may not remove stubborn sensor dirt. Photograph an evenly-lit blank white wall with a stopped-down lens as a test. If you still see dirt specks, go to the next step.

Hands-off method for most dirt: American Recorder Technologies' CO-2 complete kit with pack (CO-SOFTD, www.americanrecorder.com/catalog/default.php?cPath=10) blows a high-velocity stream of residue-free gas across your sensor to remove particulate junk. The kit costs $44 and includes six gas cartridges.

Want something cheaper? American Recorder Technologies' CO-2 Duster (CO-2) is only $22. It has three gas cartridges, more than enough for three to five cleanings.

Were you were photographing that mountain bike race in the dusty, windy Sierras at 10,000 feet? Still see spots after blowing-gas cleaning and the white wall test? It's time for more radical methods.

Don't laugh, there are some ways to make cleaning work better. Mount the camera on a tripod and angle it slightly down. Place it in sensor cleaning mode, then remove the lens.

Use a small camel's hair brush to GENTLY brush out the bottom of the mirror box. Then angle the blower bulb back and forth over the sensor to remove the least stubborn stuff. It may help to wear a headlamp to see what you're doing.

Put the lens back on, and switch the camera off and on to restore it to normal mode. Photograph a featureless white wall with the lens stopped down and view the resulting image on your computer to check for remaining dirt. Dirt specks will make a slightly bigger shadow on your sensor if they're lit by a point source like a lens' small aperture opening.

If there are still specks in your test, use the CO-2 cleaner for a stronger gas stream. Do the white wall test again.

If you STILL have dirt, lay the camera down faceup on a reasonably clean surface, put it in cleaning mode and use a couple drops of Eclipse solution on a sensor swab to clean. Then use the CO-2 cleaner to remove any dirt that fell in and test again. That should do it.

If the thing's still dirty, send it to the camera manufacturer for cleaning. But that's almost never necessary.