[VIXIV]

I was doing my routine spiffying up of my gear (wiping the body's LCDs, checking the lenses/filters for surface specks), then I saw my Dust Alert highlighted in the menu. It wasn't a few tiny specks like usual, but a broken up semi-circle on the lower half of the sensor (according to the dust alert). I found that strange since I do my little cleanings every other week or so, and my gear stays in a bag the entire time it isn't in use.

I did what I normally do:

1) Mount the camera to a tripod
2) Angle the camera downward so that surrounding dust doesn't just fall it
3) Unmount and cap attached lens
4) Flip the camera's mirror up (via sensor cleaning in the menu)
5) Use my Rocket to puff away whatever's inside the camera and the last lens attached
6) Re-mount the last lens used

I have only ever had the Dust Alert show up a handful of times before tonight in the year and a half or so I've had my K200D, but that process I just described has made the alert go away every single time before. The alert does show a lot more dust specks tonight, but I figured it would work. It didn't. So what I did next was try another lens. Same thing, except now, it's only a speck that's more or less located dead center on the sensor. I then repeated the steps I described above, and still got the same central speck. Dust Alert shows up on 2 different lenses at different locations on the sensor. I don't know why, but I figured maybe it was the lenses, so I thoroughly (and carefully) wiped the front and rear elements of the 2 lenses I just mounted and re-puffed with the Rocket. I even used a flashlight to do a little check on the insides. When I mounted them back on, alert still shows. So now I'm going crazy, and got this silly idea of checking each lens at different apertures since the dust alert showed when both lenses were set to A and the camera set them to F16 to check for dust. I clicked through every single stop on both lenses, and WOW!!! no dust alert at any stop...until the aperture was set back to the A position. When back in the A position, the camera showed a dust alert in the same differing positions for each lens.

WHAT THE HECK IS GOING ON?!

[causey]

The Dust Alert can be very misleading. Have you used it with the camera in front of a spotless white sheet of paper? Any paper wrinkle or bend can cause the Dust Alert to show things aren't there. Rather than using the Dust Alert, just wait for a clear day, set the aperture above 11 and shoot clear skies at infinity. Any dust will show up on the pics. But even if there's some dust showing on pics taken at, say, f/20, I wouldn't care to clean it, because I don't normally use such apertures, and many particles that are visible at f/20 are not visible at f/11.
Also, don't employ the blower very frequently--only when really needed. In any case, not as part of a daily routine. It may create more than solve problems. If the room where you do the cleaning is dusty, you'll introduce (with the force of blown air!) dust in the camera. I think my blower is guilty of some 'welded dust' on my sensor: dust that the blower itself can't take away, because they are stuck to the sensor. (There are methods of removing 'welded' particles as well.)