Torii Ash , Mar 21, 2010; 06:18 p.m.
Hi. I have my aperture set to f/1.4 and when i try taking a picture,it wont auto focus at all.
i usually have to manual focus just a bit, to a certain point then it starts autofocusing. It wasnt like this at all in the beginning.. its only 2 weeks old.
What could it be?or is this how its actually suppose to work? :-/
Ramon V (California) , Mar 21, 2010; 06:28 p.m.
your second statement is a little confusing to me. are you in manual mode or autofocus mode?
Charles Beddoe 
, Mar 21, 2010; 06:30 p.m.
This is likely a camera/lens settings issue, not a lens problem. Check your autofocus settings and switches on lens and camera.
Shun Cheung 
, Mar 21, 2010; 06:45 p.m.
Which camera body are you using that lens on? Have you been using this lens on multiple bodis?
On most DSLR bodies and on that lens, there should be an AF/MF switch. Try to slide both switches back and forth a couple of times and make sure everything is set to AF. Also clean the electronic contacts around the lens mount area, on both the lens and the body.
Torii Ash , Mar 22, 2010; 03:37 a.m.
Let me re-explain.
Right now i have the camera set on manual mode. Lense on M/A and focus mode on AF-A.
I try taking a picture. - The lense sounds like its struggling to move. It moves easy between 0.5 - 1, then it stuggles and i have to switch to manual mode to move it from 1 to 1.5 by turning about two times and the same with 1.5 to 3 ..while turning it, theres a strange sounds as if some plastic part is moving over another plastic part if that makes sense? Like a pepper grinder - in a sense. Isnt it supposed to be silent and why do i have to intervene when trying to focus in Auto [when it gets stuck i have to switch to manual and move it] .. moreover,i wanted to know, is the focus ring supposed to be stiff in autofocus? As seen in the Nikon 18-55mm? Because i am able to move it around even in autofocus?It isnt locked?
Torii Ash , Mar 22, 2010; 03:53 a.m.
Shun Cheung , Mar 22, 2010; 04:54 a.m.
Torii, of course it is very difficult for me to tell only based on your description, but it sounds like your new 50mm lens is broken.
However, the 50mm/f1.4 AF-S has "real AF-S"; you can manually override AF by turning the focusing ring without switching to manual focus first. You can do that with most of the AF-S lenses. But on some of the low-end AF-S kit lenses such as the 18-55, you cannot just override AF. You need to switch off AF first.
Matthew Brennan , Mar 22, 2010; 04:59 a.m.
Torii,
That grinding noise inside sounds alarmingly wrong. If you have indeed moved the focus mode switch to M and turned the focus ring by hand and it makes a grinding sound it's say there is either a broken part or a dislocated helicoid. The focus ring should only require a little effort to manually turn when in M mode and it certainly should make hardly a sound.
I would return the lens pronto.
Torii Ash , Mar 22, 2010; 05:23 a.m.
William Pahnelas , Mar 22, 2010; 02:54 p.m.
this sounds very familiar to me. i had a 300/4 lens that produced a loud, grinding sound when attempting to AF. it would not focus. this particular lens would somehow "fix itself" after a few minutes, and work okay for a while. after a few moments of inactivity, however, it would return to the grinding sounds. i quickly returned it to the seller, as it obviously failed to perform to specifications.
