I recently bought a Canon 550D, and I read it has an auto-focus motor, which not all cameras possess. I'd like to know what it is, and what I can do to keep it running smoothly; AFAIK the manual ...
I have dilemma what camera is better Nikon D5100 or D90. The first one is newer but the second one has lens servo ("screwdriver") motor. My question is: can I save some money overall with the more ...