Mount differences between Olympus and Panasonic


Mu-43 Regular
Sep 28, 2018
Real Name
I own an Olympus E-M5 MkII and a year ago I upgraded to an E-M1 MkII. The other day out of curiosity I bought a Panasonic GX-8. It is in good condition and the price was right for an older camera.

Since I am posting this in the "adapted lenses" forum you would be correct to guess that I own and use many adapted lenses. Actually, adapted lenses are pretty much my main thing.

After some initial testing I have to come to a conclusion that honestly surprises me: while the mounts on my E-M5.2 and E-M1.2 are identical in terms of how the various lenses and adapters behave, the GX-8 is different.

So far I have found several things:
- The flange distance on the GX-8 appears to be longer than on my two Olympuses. Yesterday I received a Carl Zeiss Jena 25mm 1.4 Biotar lens that originally had a pentaflex 16 mount. The person selling these on eBay adapts them to M4/3. On my E-M1.2 infinity focus is between 4 and 8 meters on the lens' scale. On the GX-8 it is at 8 meters.

I have also tried my Novoflex M42 and Canon FD adapters. One of my M42 lenses that definitely does reach infinity on Olympus with the Novoflex adapter does not reach infinity on the GX-8. Another is touch and go in that respect. My Canon FD 200/4.0 is also touch and go.

- A long time ago I picked up an F/AX to M4/3 adapter (Fuji SLR film mount). It fits into the mount on my Olympus cameras but does not turn to lock. Works on the Panasonic, if a little tight. But does not focus to infinity.

- A while ago I picked up a cheap Chinese M39 (LSM) to M4/3 adapter. On Olympus it clicks in put the little hole on the adapter side which the pin on the camera side drops into probably isn't deep enough. Result is that on Olympus the sensor doesn't activate. Panasonic? Works fine.

I don't know who is closer to spec and it doesn't matter, but I am surprised that these differences exist.

Regards, C.
Last edited:
May 16, 2017
I also have an x-fujinon adapter that worked fine on my e-m10.1 but won't rotate/lock into position on my em1.2. All native lenses work fine though.

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