[bjbj]

I bought a Canon 350D with 17-40mm lens and took some photos. I found some round dots appeared on some of the photos when I used f22 1/13s.
http://www.geocities.com/jetsobill/img_0240.jpg

But the round dots did not appear when I used f4 1/400s.
http://www.geocities.com/jetsobill/img_0237.jpg

Is there any problem with my camera and lens? Anyone can help?

[micros]

吹吹塵再試啦。

[bjbj]

I've cleaned the lens but the dots still exist.
Why the dots could not be seen when I use large aperture? Anyone have idea?

[micros]

細光圈時景深長就比較明顯。

[ChrisPoon]

I am using same equipment and also got this problem when taking picture at F20 1/125S but not that worst, only three small dots on the sky. This problem will be fixed after clean the sensor ( I discover dust on the sensor ). Hope I can help you. Chris.

[bjbj]

Did you clean the sensor by yourself or took it back to Canon Service Centre?

[ChrisPoon]

You could see the sensor cleaning function in last menu page.

*** DON'T TOUCH THE CMOS ***

I just use the "AIR PUMPER" pump out the dust from CMOS. Please also check the MIRROR in front of the CMOS. Thanks. Chris.

[bjbj]

I couldn't blow off the dust by air pump, so I needed to take it back to Canon service centre for cleaning.