Has anyone come across this problem before.
I use AI servo on the back button to focus with my 10d. A while ago, I noticed that when using my Sigma 15-30, it it seemed to jitter in and out of fcus on static subjects. ie, if I held the button down it would jump back and fore (up to about 5mm on the focus scale).
Sigma agreed it sounded faulty, and I arranged to send it back to them and used it on manual focus in the meantime, It worked on manual focus quite well, so i never actually sent it, but I decided to recently and bought a Sigma 10-20 to replace it while it was away.
Well, as soon as i put the 10-20, that did the same thing. I was aware that focus on the sigma 100-300 was a bit jittery and I always put that down to it being a long telephoto. I was convinced that it never happened on my Canon 28-135, but have realised that it does, although it takes longer for it to manifest with the button held down.
So what I first thought was an isolated lens problem, then a sigma problem, I have now realised is a canon body problem.
So I am just wondereing, before i send the body back to canon, if anyone alse has come across this or how it was overcome?
Thanks.
PS, it also happens in One Shot Focus, gets focus, beeps, stays, buit if i press again, focus moves and re-confirms.
PPS, I've tried it on flat subjetcs, so i know it's not re-focussing.
Cheers
I use AI servo on the back button to focus with my 10d. A while ago, I noticed that when using my Sigma 15-30, it it seemed to jitter in and out of fcus on static subjects. ie, if I held the button down it would jump back and fore (up to about 5mm on the focus scale).
Sigma agreed it sounded faulty, and I arranged to send it back to them and used it on manual focus in the meantime, It worked on manual focus quite well, so i never actually sent it, but I decided to recently and bought a Sigma 10-20 to replace it while it was away.
Well, as soon as i put the 10-20, that did the same thing. I was aware that focus on the sigma 100-300 was a bit jittery and I always put that down to it being a long telephoto. I was convinced that it never happened on my Canon 28-135, but have realised that it does, although it takes longer for it to manifest with the button held down.
So what I first thought was an isolated lens problem, then a sigma problem, I have now realised is a canon body problem.
So I am just wondereing, before i send the body back to canon, if anyone alse has come across this or how it was overcome?
Thanks.
PS, it also happens in One Shot Focus, gets focus, beeps, stays, buit if i press again, focus moves and re-confirms.
PPS, I've tried it on flat subjetcs, so i know it's not re-focussing.
Cheers