Do sensors wear out?

[MATT_GODFREY]

I recently bought a d200 from a firend who had it as a back up camera and was selling it due to upgrading all his kit to d3 & d300,got at good price and was happy with it up until recently.
Lately i have been shooting in sort of overcast days where the sun isnt quite as bright and it has caused me to use slower shutter speeds,bigger apertures and up the iso if i cant get away with it. But for some reason my pictures arent coming out as sharp as id like nor are they good quality. when i zoom in 100% the picture appears grainy(even when shot ISO100). i also recenlty submitted 4 photos to alamy.com and had all 4 knocked back to due soft focusing and or loss of detail. could this be the camera? or is it me? the more i write this the more i think it could be me rather than the camera. Also the lense i have isnt the best so i could well be compromising quality there also(70-300). i try and keep my post processing to a minimum to try help preserve quality.
anyone any ideas? oh yes, and do cameras sensors wear out?
cheers,
matt

[beejaybee]

Wear, no, but they can fail partially or completely.

But if you're getting soft images then the sensor has nothing to do with it - the most likely fault is with focusing, try focusing manually, deliberately going a shade "in front of" & "behind" the subject to see if one or other is sharper. Practice holding the camera steady & use short exposures - less than half the reciprocal of the focal length e.g. with a 200mm lens you want a shutter speed of 1/400 sec or faster. (A longer shutter speed may be acceptable if your lens has image stabilization). Finally all digital images need some sharpening, but not all that much - see the article in this week's AP.

[Monobod]

Slower shutter speed could lead to a bit of camera shake and larger apertures to a shallow depth of field. Either one could be causing your problem. Have you tried using a monopod? They can remove the vertical element of camera shake and any very slight sway front to back would be overcome by the depth of field latitude or a fast autofocus. Unless you are photographing very close objects with a wide aperture the depth of field should not be a problem requiring you to use a tripod and remote release.

[geoffL]

I'm assuming these were your 4 sample images to register with Alamy? My experience is that Alamy are pretty unforgiving when it comes to picture quality - they can afford to be given the size of their library. Photos need to be pretty well perfect technically - it won't take much for them to be considered too soft. As well as the good points made about re focussing, use of tripod etc you also need to take care in the processing as if you are too harsh with your treatments this can also cause probs. Another point to consider is that you will have had to interpolate the image from that camera to make the image file large enough to meet Alamy requirements. What software did you use? This can also introduce softness.