Last week I bought a brand new Sigma 8-16 from B&H ... today, I mounted it on my camera for maybe the 2nd time... and no AF.
To tell the truth.. I got the 8-16 the same day as my 35L... so, I really wasn't playing with the 8-16 much.... and I really can't say for certain that the AF ever worked on it...
So.. it got boxed back up and sent back to B&H.... now it's the waiting game.... I have to wait for them to get it... then refund my cash.... then... I'm debating on whether or not I'll order another one from them.
***Crazy Thoughts warning *** The following text will be regarded as insane by most.. feel free to not read any more.
The thing that bothers me though... and I know it's irrational... is that I rented this lens and liked it... so bought one with plans to use it for Christmas... now, there's no chance of that.. B&H won't do what they have to do in time for me to get the refund, get another one ordered, and have it delivered by Christmas... now... as I said, I know this is irrational.... but, in the last year, I've bought a 7d, a 70-200 f/2.8 IS II, 24-70, 35L, and the 8-16 all from B&H... so.. damn near $6k worth of stuff... and each transaction, I give them a thousand dollars or two... and trust that they will deliver my ordered products... however, this trust is a one way street... even after spending a ton of money with a retailer.... In my delusional world, they'd look at my past as a customer with them... and as soon as they see that the package has been shipped, they'd send me a new lens... They'd say "Hey... this guy has spent $6000 with us this year.. I doubt he's going to try to screw us over with a $700 lens..."
I wish I had a local camera shop... I feel that with a local shop, I could have walked in the door... tossed them the failed lens, and walked out with a new one.

