Spots after cold weather shooting

[kevinma]

Out taking pictures this afternoon (cold, -15C/5F). On looking at the images on the computer, I noticed 2 spherical darkish spots in most of the images in the same area of the image. I can't be sure if they are in all because of the background in some of the images. Likewise, I can't be sure if they were there in the first image. I've just taken a couple of indoor shots and they're gone. What caused these?
Kevin.

[scottbergerphoto]

It sounds like sensor dust which is more apparant at small apertures (higher f) and against skies.
Scott

[kevinma]

Thanks Scott; that would explain why they weren't there with the indoor shot (bigger aperture). I'll investigate the post on this page about sensor dust...
Kevin.

[Jim_T]

Yes... The aperture is what brings out the dust..

Put the camera in manual focus and shoot the sky at f/22.. A cloudy sky is usually best.. That' will give you an idea of how much dust is on your sensor..

[scottbergerphoto]

It also helps to open the image up in PS or PSE and run auto levels.
Scott