Focus hunting when using Canon lenses on Sony bodies with Sigma MC-11?

Kit Lens Jockey

EOS 7D MK II
Nov 12, 2016
528
190
Has anyone experienced some focus hunting issues when adapting Canon lenses onto Sony bodies? I recently got a Sony A7 III, and the performance so far has been pretty impressive, especially considering the adapted lenses. However, occasionally the lens will just go completely berserk when focusing. It acts kind of like a Canon lens on a Canon camera when it can't achieve focus and you have "Lens drive when AF impossible" set to "on." The focus racks way out, to the point where you have to grab the focus ring and twist it just to get the lens back to some kind of reasonable focus. At first I thought this was just the camera struggling in low light, but it's done it a few times in decent lighting. If I could just iron out this bug, I think this camera would really be viable to use with Canon glass, and I have to admit that it's got some very solid features. Hoping that Canon can come out with something that has all this technology and a menu system that isn't garbage. ::)

For reference, I'm using a Canon 50mm 1.2L and a Sigma MC-11 at the latest firmware on the Sony A7 III. I'm going to try a Metabones adapter as well to see if that's any better, as admittedly the Sigma adapter says straight up that it's only meant for use with Sigma lenses.
 

Talys

Canon 6DII
Feb 16, 2017
2,058
329
Vancouver, BC
Kit Lens Jockey said:
Has anyone experienced some focus hunting issues when adapting Canon lenses onto Sony bodies? I recently got a Sony A7 III, and the performance so far has been pretty impressive, especially considering the adapted lenses. However, occasionally the lens will just go completely berserk when focusing. It acts kind of like a Canon lens on a Canon camera when it can't achieve focus and you have "Lens drive when AF impossible" set to "on." The focus racks way out, to the point where you have to grab the focus ring and twist it just to get the lens back to some kind of reasonable focus. At first I thought this was just the camera struggling in low light, but it's done it a few times in decent lighting. If I could just iron out this bug, I think this camera would really be viable to use with Canon glass, and I have to admit that it's got some very solid features. Hoping that Canon can come out with something that has all this technology and a menu system that isn't garbage. ::)

For reference, I'm using a Canon 50mm 1.2L and a Sigma MC-11 at the latest firmware on the Sony A7 III. I'm going to try a Metabones adapter as well to see if that's any better, as admittedly the Sigma adapter says straight up that it's only meant for use with Sigma lenses.
Yes. The MC-11 you're using is the best of the options, too.

The focus hunting drove me batty, because it's not the 50% of the time when it works well that I remember, it's the 15% of the time when it's has to hunt a bit and the 5% of the time when it fails miserably that drives me nuts.

Technologically, no question, the MC-11 is impressive and just fine for playing with or occasional use, and certainly ok for specialty lenses and manual focus situations, but I don't think it's acceptable for "real work" in general -- if you love the system, buy native glass, IMHO.
 

Kit Lens Jockey

EOS 7D MK II
Nov 12, 2016
528
190
Meh, I don't love the system. I've been tolerating the system so far because of the advantages it has. I want Canon to come out with something that competes. But I'm working on an important project this summer, and I wanted to see if the Sony might be useful to me.

One thing I have noticed, there's very little focus missing. If it does manage to lock focus, it pretty much nails it every time. That's really really nice.

Oh, and the sensor cleaning on the Sony kind of cracks me up... With Canons you just see a little animation on the screen, and you trust that it's doing something in there. With the Sony, hold on tight, because when you run the sensor cleaning, that sensor is moving in there. ;D I guess that's something else IBIS is good for... A vigorous sensor cleaning.

Last, regarding the focus hunting, I'm starting to learn that what really sets it off is if you try to autofocus and the point you have selected is not pointed at something with a decent amount of contrasty edges. Good light or not, try to focus on something that's not contrasty, and it's going to freak the camera out.