A7S Metabones Smart Adapter MK IV Autofocus issues

B

Brad12d3

Member
So I mainly use my A7S for video, however I do like to do a bit of photography. I was just playing around with taking some photos using my A7s, Metabones EF to E Mount Smart Adapter MK IV with a Canon 24-70L MK I lens. The autofocus is abysmal in this set up. It is astonishing how difficult of time it has locking on to anything. I am playing around with different autofocus settings but results aren't great.

Is there anything else I should be trying, or do I need to buy a proper e mount lens if I want to have decent autofocus?
 
Never heard of any decent result with adapters and auto focus... The new Sigma adapter seems to work reasonably well with Sigma canon glass for photos but that's about it. Been avoiding adapters as they seem to be more trouble than they're worth...
 
The simple explanation here is that DSLR lenses are designed to operate with Phase Detection, and your A7S doesn't have that.

Mirrorless cameras until recently didn't support Phase sensor points at all (traditionally, we used the mirror to bounce light to the array before snapping the picture. But now we, uh, have no mirror!). The phase points are required to measure the distance to your subject and snap the lens into place. Without that sensor, we rely on judging the contrast of the pixels to determine focus. Since the camera doesn't know how far away you are, it has to make educated guesses and determine focus by trial and error. Native E-mount lenses are designed to do this at very high speed, by using small and efficient focus elements. Conversely, this is why E-mount lenses are almost always Focus-by-wire. A DSLR lens can have a motor driving a mechanical gear since it only needs to snap into a precise location in one movement.

Newer Sony cameras like the A6300, A7ii and A7Rii actually have phase arrays ON THE SENSOR, which can even drive adapters full time. That means a Metabones on an A7Rii can focus at nearly the speed a Canon body can. However, on an A7S, which relies only on Contrast, it will hunt back and forth a lot trying to figure out where to go, and the lenses simply aren't made to make those small repetitive movements that fast.
The only adapter that WILL drive lenses full speed on an A7S is the official LA-EA4 from Sony. That's an A-mount adapter for Sony's older lenses (the design they inherited from buying Minolta), and includes its own phase detection mirror in the adapter! I have one and use it to shoot photos with cheap Minolta and Sony DSLR glass, and it focuses nice and fast and accurate! It does have limitations in video mode however- the lenses are noisy and not silent, which may show up in your video footage. And the real annoying bit is that Sony's AF system locks the aperture to F/3.5 (or as close as possible). This is true of all Sony A-mount cameras as well, so its something about how they chose to make focus work. Flip it to MF, and you have full manual control of everything.

I'm hoping the A7Smiii will finally have PDAF points on the sensor. In the mean time, consider an A7ii or A6300 if you want to adapt Canon lenses and focus at full speed!
 
I have an A7rii and the same Canon 24-70L MkI lens as you with the Matabones MkIv.

Out of all my lenses, the Canon 24-70 performs the least reliably in terms of focus so that may have something to do with it.
For stationary objects and decent lighting it works great, but get out of those conditions and it goes back in the bag.
 
M. Gilden said:
The simple explanation here is that DSLR lenses are designed to operate with Phase Detection, and your A7S doesn't have that.

Mirrorless cameras until recently didn't support Phase sensor points at all (traditionally, we used the mirror to bounce light to the array before snapping the picture. But now we, uh, have no mirror!). The phase points are required to measure the distance to your subject and snap the lens into place. Without that sensor, we rely on judging the contrast of the pixels to determine focus. Since the camera doesn't know how far away you are, it has to make educated guesses and determine focus by trial and error. Native E-mount lenses are designed to do this at very high speed, by using small and efficient focus elements. Conversely, this is why E-mount lenses are almost always Focus-by-wire. A DSLR lens can have a motor driving a mechanical gear since it only needs to snap into a precise location in one movement.

Newer Sony cameras like the A6300, A7ii and A7Rii actually have phase arrays ON THE SENSOR, which can even drive adapters full time. That means a Metabones on an A7Rii can focus at nearly the speed a Canon body can. However, on an A7S, which relies only on Contrast, it will hunt back and forth a lot trying to figure out where to go, and the lenses simply aren't made to make those small repetitive movements that fast.
The only adapter that WILL drive lenses full speed on an A7S is the official LA-EA4 from Sony. That's an A-mount adapter for Sony's older lenses (the design they inherited from buying Minolta), and includes its own phase detection mirror in the adapter! I have one and use it to shoot photos with cheap Minolta and Sony DSLR glass, and it focuses nice and fast and accurate! It does have limitations in video mode however- the lenses are noisy and not silent, which may show up in your video footage. And the real annoying bit is that Sony's AF system locks the aperture to F/3.5 (or as close as possible). This is true of all Sony A-mount cameras as well, so its something about how they chose to make focus work. Flip it to MF, and you have full manual control of everything.

I'm hoping the A7Smiii will finally have PDAF points on the sensor. In the mean time, consider an A7ii or A6300 if you want to adapt Canon lenses and focus at full speed!
Click to expand...
I don't think MB ever digs into the PDAF sensors. It uses contrast detection AF on all cameras. Hence the issues....
 
optitek said:
I don't think MB ever digs into the PDAF sensors. It uses contrast detection AF on all cameras. Hence the issues....
Click to expand...

False. The issues don't exist on newer cameras with PDAF sensors.

Remember, the adapter doesn't get to decide what the camera uses anyway. Only the camera does. Try a MB on a mark ii model with phase sensors, and you'll get a very difference experience. Even the cheap knock off adapters focus fast in this setup. See video below demonstrating native vs adapted lens on an A7Rii:
(jump to about 6:13 to see the adapted lens)

Keep in mind, all the MB and others like it do it emulate the signals by Sony's own adapter protocols, originally designed for adapters like the LA-EA3. At first E-mount was only contrast, so these protocols were slow and laggy trying to drive DSLR lenses. Then they added PDAF as part of the hybrid AF system (A6000, A5100, A7, A7R), but the LA-EA3 (and therefore MB and others) were still treated with the same contrast protocols as the older contrast only cameras (in other words, it doesn't use the PDAF sensors).

The A7Rii was the first the change that. They advertised that the camera could drive adapted lenses like their legacy A-mount without a mirrored adapter, since the focus system was that good. It turns out, the new focus protocols are now designed to be able to drive PDAF full time, even on adapters like the LA-EA3. They even went back and supported it on the A7ii with a firmware update since it uses the same newer focus system, and the A6300 has it as well. Therefore all adapters that emulate Sony's own protocols also get to use PDAF for adapted lenses on all cameras released since then.
Sadly, this won't be a reality on the A7S unless the mark iii adds the PDAF components to the sensor. We just physically lack the hardware to do it. :(
 
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^^^This and his previous post is correct. Without PADF adapted lens AF is bunk. I own the A7rII, A7s and a5100 - two of those do well with my adapted Canon lenses. The A7s hunts and hunts before finally locking and its usually just ratcheting the lens little by little. The a5100 is fast and the A7rII focuses really fast and accurate, its clearly the best of the three Sony bodies I shoot, and most of the time it just snaps into focus.

I passed on the A7sII because Sony neglected to upgrade the AF. I'll buy the A7sIII if it gets a PADF array and if they bump the MP a bit so we can shoot 4k in FF and s35 mode, even if there's a crop in s35.
 
Chris Joy said:
^^^This and his previous post is correct. Without PADF adapted lens AF is bunk. I own the A7rII, A7s and a5100 - two of those do well with my adapted Canon lenses. The A7s hunts and hunts before finally locking and its usually just ratcheting the lens little by little. The a5100 is fast and the A7rII focuses really fast and accurate, its clearly the best of the three Sony bodies I shoot, and most of the time it just snaps into focus.

I passed on the A7sII because Sony neglected to upgrade the AF. I'll buy the A7sIII if it gets a PADF array and if they bump the MP a bit so we can shoot 4k in FF and s35 mode, even if there's a crop in s35.
Click to expand...

Interesting that you find the a5100 faster than the A7s... I own an A5100, I tried it once or twice with my commlite, and it definitely still does not use PDAF. However, the A5100 might just be a snappier system overall, hence why it might be faster than the A7s but still leaps and bounds worse than the A7Rii, which practically feels native with it. I'm curious if the MC-11 would make a difference on the A5100 since it supposedly can tap the PDAF when working with Sigma lenses. I haven't heard any confirmation of that combo being any good though. I'm wondering if the older (pre A7mii models) that had the hybrid AF system still require some CDAF to focus, whereas the newer ones can do PDAF full time?
 
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