Dirty Lens or Sensor

[drewpost]

Hey everyone! I'm coming here looking for some help. I have a new 40D with the sensor cleaning feature. I am on holiday at the moment visiting family in Colorado and I just noticed some spots in the upper left hand corner of my shot. I'm not sure if it's on the sensor (which would be weird with this new feature) or somewhere on the lens (a 17-85 4-5/6). I have a 70-200 2.8 IS that the spots do not show up on so I'm not sure where the debris is!

Can anyone take a look at this and see a) if they can tell where the debris is b) other 40D owners, have you had dirt sensor not work for you?

BTW, I was having some issues embedding an image here, the direct link is

http://homepage.mac.com/drewpost/debris.jpg

 

[*Mike*]

I'd put my money on it being sensor dust. The anti-dust features on C/N are far from perfect... although a step in the right direction.

Are you sure it's not there with the 70-200? Have you taken a test exposure to check - not just looked at your typical shots?

 

[tirediron]

Do a test shot against a light-coloured wall with your 70-200, stopped right down and see if the spot appears there; they're less noticable at wider apetures, but that looks like sensor dust to me too!

 

[Garbz]

Indeed that would probaly not be visible at f/2.8 or at 70mm. But shoot at 17mm f/22 and it should turn to a very dark black dot.

I suggest in the absence of any cleaning equipment set the camera to cleaning mode that opens the shutter, remove the lens, and while holding the camera upside down gently blow into it from a distance making sure that you don't spit into it and the surrounding environment is clean and doesn't make matters worse, and that it's warm enough that you don't fog up the LPF on top of the sensor.