Allan martin wrote:
I just bought my second sigma lens, a 17-50 for nikon cameras, and I didnt know it had a focus switch (AF/M). Unlike my other sigma, 10-20, which has manual override. (minor drawback of the 17-50, lens like that should have override!)
This is a well known complaint/trade-off of the lens.
I tried to twist the focusing ring while the switch was set to AF and, although it was hard to do it, it could be moved.
Yes, it was wasn't it?
Later I read on the manual that I shouldnt be doing that because it might damage the AF mechanism.
Yes, they certainly do try to let you know it's not good to do.
Do you guys think I somehow already screwed it? How can I test to see if everything is alright?
When you move it to manual and try turning the ring, does it feel ok? The focus ring is overly-loose-ish anyway. If it turns smoothly and goes to its hard stop, you're more than likely fine as everyone else here has said. It only rotates about 45° so it's not like it's got far to go (another complaint).
I'll bet 80% of purchasers do this and then wonder why it's so hard to turn! They should probably put some sort of sticker over the switch with a /!\ warning.
Just don't do it again! You'll also notice that the zoom sort of breaks in after a while and gets smoother.
BTW, it's an absolutely amazing lens (in spite of these foibles), you're going to love it. I hope that the next rev of it is an "Art" version. As I've said before, this lens is one thing that's keeping me from jumping on FF. Every time I use it I wonder why I don't use it more!