Anybody else having trouble with the Sigma 30/f1.4 (or any other Sigma lens) on the 7D?
I've already handed of my old 30D, so I can't directly compare focus with the 30mm on the 30D vs 7D, but my recollection is that the Sigma 30mm worked better on the 30D (though reliable AF was never the lens's strong point).
On the 7D the 30mm seems to routinely front focus when camera to subject distance is less that 6 or 8 feet -- and I've been unable to correct this using the microfocus adjustment. At about 10 feet the AF seems to improve (focus adjustment of +5 seems spot on). But when getting closer to the subject it front focuses. I've tried a variety of microfocus adjustment settings at 6 feet and the adjustments seem to have remarkably little effect.
Could this be due to the new AF system in the 7D that the Sigma just isn't prepared to handle? Might a trip to Sigma fix up the lens? (And would I need to send in the body, too? -- not sure I'm prepared to do that anytime soon).
Can't comment on the 30/1.4 but I've had the sigma 50/1.4 front-focus on the 7D we were shooting with last weekend. As in your case, focus adjustment was not of much use, specially when the subject is close. There was no focus problem when I tried with my canon 50/1.8.
In your case, is this the only lens that mis-focuses?
I noticed my friend's 30 FF on his t1i as well. I keep it quiet thought cause not good o tell him he should have gotten something with AF adjust. So that being the case I think it's less likely problem with the camera. Especially if it doesn't happen for other lenses.
Haven't tried my sigma 30mm yet, or at least not enough to form an opinion on it's focusing with the 7D. I know the 70-200mm f2.8 has become a crapshoot on the 7D. The sigma 70mm macro on the other hand is working great with it. I'll try to test my 30mm when I get 2 minutes of time to rub together.
vince wrote:
In your case, is this the only lens that mis-focuses?
Yes. So far the Sigma 30 is the only lens that I've noticed with focus issues. A couple other lenses took a small micro-adjustment (+3,+5, somewhere in that range), but many lenses seem to focus well with no micro-adjustment.
I noticed my friend's 30 FF on his t1i as well. I keep it quiet thought cause not good o tell him he should have gotten something with AF adjust. So that being the case I think it's less likely problem with the camera. Especially if it doesn't happen for other lenses.
It may have been harder to tell on the 30D, but I'm quite sure it wasn't as bad as it is on the 7D. I actually sent back my first copy of the Sigma 30mm due to focus issues and went to a brick and mortar place where I could try a few copies -- my current copy made me reasonably happy on the 30D. And the 7D front focuses badly enough that it would have been obvious even on the 30D.
I don't think it's a problem with the camera (or the lens, really, since it worked well on the 30D). I think it's a problem with the lens-camera combo. I'm guessing (wildly speculating) that the 7D AF system is different enough to confuse the older electronics in the Sigma lens (which may have been reverse engineered from earlier Canon AF systems)
