i have a quite noisy lens, when i use it on AF mode. the lens is a fixed 50mm, nikkor. to me, it has always been like this, since i got it second hand. now, does anyone have an idea about why is it noisy? and thus, how could i (in case i could) "silent" it? actually, it doesn't bother too much, but makes me feel my camera like an old crappy toy ...and it is a not-that-old wonderful toy!