spots on photos

i have an 18-55mm lens with my canon 400D- the one that came with the camera.

I THINK that this only happens with this lens - On landscape photos - most

noticeable in the sky, I see slightly darker spots. Not massive and semi

opaque.

Can these spots be caused by dirt inside the lens or do i need to thoroughly

clean both ends of the lens, If the latter what would you recommend

 

Thanks

John

it would help if you would show us an example, but by your description it sounds like dust on your sensor. It may be that you don't see it on other photos taken with different lenses because you shoot at different apperture or the background is not as uniform and bright. In my experience dust on the lens would be noticeable only if it's on the back element as it is physically closer to the focal point. Dust on the front element usually results in flare rather than specks on your film/sensor. I would suggest you clean your sensor with a dust blower, and check the back element of your lens for noticeable scratch or dust spot. Good luck

Maybe it only happens with this lens because this is the one you use, stopped down, for landscapes. Try shooting a blank light coloured wall at f/22, then again wide open. Shutter speed and focus are unimportant. Check the images on the computer. If the spots are there at f/22 but disappear at f/4, then it's sensor dust. Search under "sensor cleaning" for more information than you could ever want!

Thanks Geoff and Michael. I think it mostly happens around f22. I will at sensor cleaning on the net now. the 400D is supposed to have an automatic sensor cleaner but it may be that isn't working well enough,

If you have dust on the sensor, the spots will get sharper the more you stop down. If you see them at f22 but they disappear or fade some and get bigger at wide apertures, clean the sensor.

http://www.cleaningdigitalcameras.com/