Why would an EF adapted lens have better af than 4/3 adapted lens?

SteveNunez

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Why would an adapted EF mount lens work significantly better than an adapted 4/3 version of the same lens using a Panasonic G9 (FW 2.4)? My Oly EM1 has no issues using either lens but the Pan G9 only works well with the EF version of the Sigma 150-500 and barely works with the 50-500 4/3 version....I would have thought the 4/3 version would have worked better but with the G9 this isn't the case- any ideas why? (The EM1 works well with both lenses adapted!)
 

DeeJayK

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First big difference, which you likely already know, is that the E-M1 offers Phase Detect AF, while the G9 is limited to Contact Detect AF.

That would explain why the 4/3 lens would work better in the Olympus than the Panasonic body. But it doesn't explain why the EF lens outperforms the 4/3 lens. Could it be because the Sigma is just a more modern lens with a better focusing motor? That's just a guess. I have zero experience with EF lenses.

- K
 
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I don't have any experience with an EF lens on an M43 camera either. My understanding is that you'd need a "smart" EF-M43 adapter for the AF to work with an EF lens, and some of those cost more than the lens. My former ZD 50-200 SWD and 12-60 SWD focused fairly quickly on my EM1 II, but M43 native lenses were even faster. The 50-200 was bog slow on my EM5. My understanding is that most 4/3rd lenses were made for PD-AF, while M43 lenses were made for CD-AF. My 4/3rd Sigma 105 f2.8 macro is slow to focus on any camera primarily because it uses a slow screw-drive AF motor. Later versions of the lens for other camera mounts got upgraded AF motors.
 
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Why would an adapted EF mount lens work significantly better than an adapted 4/3 version of the same lens using a Panasonic G9 (FW 2.4)? My Oly EM1 has no issues using either lens but the Pan G9 only works well with the EF version of the Sigma 150-500 and barely works with the 50-500 4/3 version....I would have thought the 4/3 version would have worked better but with the G9 this isn't the case- any ideas why? (The EM1 works well with both lenses adapted!)

When the 50-500 was released the only type of focusing on cameras was PDAF and the motors needed for PDAF focusing is different than those for CDAF. So most of the 4/3 lenses work like crap on CDAF only cameras, even the CDAF optimized ones don't work all that well on a CDAF only camera. The 150-500 uses new motors that actually work well for both CDAF and PDAF focusing.

as an aside, the 50-500 is the worse focusing 4/3 lens that I own.
 
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