AF/C with Canon Lenses & A7rII

[Ivan]

Hi

 

Can anyone please give me some feedback regarding the AF/C preformance with Canon lenses using the Metabones adapter. Thanks

[joema]

I have tested the A7RII with my Canon 17-40, 24-105 and 70-200 2.8 IS II (and 1.4x TC III) using the MB IV adapter. C-AF works with these lenses but not nearly as reliably as on my 5D3. That is using the latest Metabones 0.41 firmware. In general at wider angles, deeper DOF and brighter light it does better. At 200mm f/2.8 in dimmer light it's less reliable whether in AF-S or AF-C.

 

The behavior is inconsistent and unpredictable. It sometimes exhibits a cache-like phenomenon whereby it will rapidly acquire focus as you pivot between between two different objects that have been previously acquired. It feels almost like the native lens on a Canon body. At other times it hunts endlessly in the same conditions and on the same objects.

 

I could shoot a commercial showing only the success cases, and you'd see little green squares snapping to the object, lightning fast with total accuracy. But in the real world of event shooting we usually cannot ask for a re-do -- we have to get the shot. Just because the AF system is lightning fast 70% of the time doesn't help -- we need 98% reliability or better.

 

Whether AF-C or or AF-S, I would not trust Canon lenses on the A7RII on a "must get" shot like a wedding. OTOH there are probably less critical situations where it's useful. It does basically work, but feels roughly like early beta-quality software. 

 

By contrast when using my Sony 28-135 f/4 lens, the AF system is really fast and accurate in both AF-S and AF-C. I assume it's similar for other Sony lenses. Maybe not *quite* as fast or reliable as my 5D3 and Canon L lenses, but it's very good.

 

In video mode with Canon lenses and the Metabones adapter, there is only single-shot AF and it's not very fast or accurate. Even the 5D3's single-shot contrast-detect video AF seems better.

 

Video mode AF with the Sony lens is pretty good. I'm still testing how reliable it would be in a production situation.

 

Beyond just focus acquisition is tracking, which usually means predictive fore/aft tracking toward/away from the camera. I haven't tested that thoroughly but since the Canon/Metabones combination sometimes often struggles with static subjects, I can't imagine it working super-reliably on a rapidly moving subject. 

 

Maybe I should just be impressed it works at all. The ability to interchange Canon lenses between my 5D3 and A7RII is very handy, provided I don't try to shoot an indoor swim meet on the A7RII using a Canon lens.

[Ivan]

Thanks Joema again

[bplet]

Agree with Joema's assessment.  If you're curious about specific lenses, here's what I've found thus far...

 

24Lii:  Brilliant.  Locks on to everything, even using the smallest spot.  Just as fast as on my 5D3, but exponentially more accurate and consistent.  I've always adored this lens, but it misfocused so often wide open.  This lens is a rock star on the R2

 

100L Macro: Totally unusable AF.  Can't lock on to anything.

 

24-70 f/2.8 ii:  Fast and accurate at almost all times, at the wider end of the zoom range.  Count on consistency from 24mm up to around 50mm.  Once you're up in the 60-70mm range, it starts to get more hit and miss.  Will sometimes lock on without any issues, and other times will just hunt back and forth.

 

70-200 f/2.8 ii:  Much the same as the 24-70.  Fast and accurate, but results start to get more hit and miss once you pass the 135 mark.

 

With both of those zooms, that not to say they never lock on when zoomed all the way in.  They often do, but then you'll try a different target and it just hunts, with no apparent rhyme or reason. 

 

85L ii:  This one has surprised me.  I expected AF on metabones to be HORRIBLE, as it can be sorta slow and hunty on Canon bodies.  It's actually not bad at all.  Very accurate, and locks on well.  I wouldn't call it "fast", if you've got the 85L, you know it's not fast in the first place.  Every now and then it has trouble in dim light or areas with very little contrast, but for the most part it's pretty solid.  Also, gotta say, manual focusing at f/1.2, focus peaking is shockingly effective, because there's such rapid fall off of detail, you really can see where that focus is falling  

 

135L:  Totally unusable AF.  Either hunts endlessly, or just gives up and sits there.  MF'ing at f/2 is very easy though

 

40mm Pancake:  Quick, reliable, nails everything.

 

Some of the early "preview" videos seemed to want to paint the R2/metabones combo as the answer to everyone's dreams, perfect performance, yada yada.  It's not perfect.  Compared to adapted lenses on almost any other camera body available, it's amazing.  But it's not a situation where every lens performs exactly as well or better as on Canon bodies.   (some do all the time, some do at certain FL's, some don't at all)

 

One thing I keep trying to remind myself of, however, is that I'm getting almost twice the pixels that I get with my 5D3.  So if I'm shooting with the 70-200, I try to remind myself to not always feel the need to zoom all the way in if it's a make or break shot.  e.g. A shot at 120mm, that it nails right away, can be cropped in even tighter than a properly framed 200mm shot on the 5D3.  Still though, that's sort of a justification... it'd be nice if it would just nail everything at all times, even when zoomed in to 200mm, but you work with what you've got.  Performance is very dependent on the adapter, so hopefully Metabones will keep experimenting with the formula.  

 

My biggest gripe with the Metabones, honestly, is ergonomic.  I've got long fingers, and the knuckles of my middle and ring finger end up resting against the sharp knurled ring of the adapter, leaving my knuckles feeling scratched/raw after a lot of use.  I keep meaning to gaff tape that side of it, but... you'd think someone might have thought of that over at Metabones

[Christo25]

Again, agree with Joema. I have so far only got round to testing the 70-200 2.8 ii and it works fine in great conditions but inside my house in daytime it struggled on a lot of subjects. It really seems Sony has some people out there putting up posts that really make it look a lot better than it is! I also tried the sigma 35mm 1.4 which was very quick for about three shots then it would stop working. Swapped the metabones adaptor as I have a spare (both mark iv) and the same happened so not sure why??