[shuttertalk]

I'm just looking into compatibility of four thirds and micro four thirds system lenses. Apparently the Four Thirds system is built upon an open set of specifications, where as the MFT system is not - and currently only Panasonic and Olympus are playing in that space.

So far I know both Olympus and Panasonic have adapters so that you can use Four Thirds lenses on Micro Four Thirds cameras, although some functionality may be lost

Are the four thirds lenses compatible between brands, since they're an "open standard"? i.e. can Olympus lenses be used on a Panasonic body?

[matthew]

All Four Thirds lenses, regardless of manufacturer, can be used on any Four Thirds SLR. Bodies are made (and/or branded) by Olympus, Panasonic, and Leica, although Olympus dominates the others. Lenses are made by Olympus, Panasonic, 'Leica', and Sigma. Even though it is called an 'open' system, that's mostly a marketing invention to give them the impression of weight. Officially, Fuji and Kodak are also members of the 4/3 group, even though Panasonic quickly replaced Kodak as the sensor supplier, and Fuji never really did anything.

Micro Four Thirds is essentially the same major players, but this time Panasonic has taken the lead, which is not too surprising since Live View was really their invention. (The Olympus E330 made it to market first, but uses Panasonic's sensor.) Any micro four thirds lens can be used on any micro four thirds body, regardless of who makes it. While there's no reason why Sigma couldn't slap a MFT mount on one of their lenses, there's no practical reason for them to do it. The MFT advantage is its small size, which only comes from completely new optics.

And yes, having two similar terms for similar-but-incompatible lens-mounts is very confusing. I'd say that it's even more confusing than EF/EF-S or DX/FX lenses, but perhaps not as bad as AF-S and AF-D.

The key to compatibility is the flange distance - how far the mount is from the sensor - and the diameter of the mount. Nikon has a large flange distance, which is why people can get an adapter to put the 14-24/2.8 on a 5D; Leica's mirrorless M-mount has a very short distance, much too short for an SLR, which makes their ability to be used on adapter-equipped Micro-FT bodies very special. Today I got to play with a Leica 50mm f/0.95 Noctilux on a GH1 - not too shabby. But I digress...

ANY lens that isn't a Micro Four Thirds lens needs an adapter before it can be used on a Micro Four Thirds body. (A running list of the ones that I've tried can be found on `thews reviews.) There's a huge number of them out there, and there are only two real advantages of using a Four Thirds SLR lens on a Micro mirrorless body. One is that they retain full electronic integration with the camera for aperture control, fly-by-wire focusing, and EXIF data. The other is that they're designed for the smaller sensor and its higher pixel pitch: they really are smaller and sharper than the other SLR lenses that are commonly available. (i.e., not a Leica R mount.) I bought a 4/3-to-m4/3 adapter just so that I can use my Olympus 50/2 lens on the GH1, because none of the Nikon lenses that I use on my F-to-m43 adapter can match it.

But like you say, just because the lenses can mount doesn't mean that they're fully compatible. Expect manual focus and stop-down metering for any lens mounted on an adapter. If your lens doesn't have an aperture ring (Nikon G-series, for example) then you need a much more expensive adapter to make them work. Lenses with only electronic aperture selection (Canon EOS) are fixed at their default apertures with no control possible, at least as far as I've seen. Other electronic features, like optical stabilization, are also gone.

But getting back to the question: "can Olympus lenses be used on a Panasonic body?" - the answer is Yes, But. The "But" is that they use different types of image stabilization, so sometimes they cancel each other out. Olympus uses in-body, while Panasonic uses in-lens. So no Olympus lens will be stabilized on a Panasonic body, and Panasonic lenses with stabilization need to have it disabled when on an Olympus body. That really has nothing to do with the press-release fiction of 'open standards', but is simply because Olympus and Panasonic shared the development for both the original and the new Micro Four Thirds systems.

[shuttertalk]

Thanks for the explanation Matthew - great stuff here. You're a walking camera encyclopedia!

So if you're using FT lens on a MFT, you probably won't get stuff like Autofocus because of the additional adapter.

Just clarifying - Is an adapter required if using an Olympus MFT lens on a Panasonic MFT body? And do you lose functionality like AF again?

Just from a pretty naive viewpoint - it would be better to get a Olympus MFT body so you can have in-body stabilisation, and also have the whole stable of Olympus and Panasonic MFT lenses available to use?

[matthew]

Autofocus from FT to MFT is iffy. It won't work on the older Panasonic micro bodies at all, but I've heard that it might on the new G2. Olympus SLR (FT) lenses on Olympus Micro bodies often do autofocus, even if the specs say that it won't, but even the ones that are officially supported are quite slow. Only the newest SLR Four Thirds lenses, like the 14-54mkII, have been designed for the rigours of contrast-detect autofocus. It's still a better match than other system's lenses, though, since the cameras can be configured to automatically magnify the viewfinder when it senses the focus ring turning - aka 'manual focus assist'.

No adapter is needed to go from one brand of Micro camera or lenses to the other - it's the exact same lens mount. (It's not completely unique to FT & mFT; Fuji SLRs used the Nikon F-mount, and Kodak made cameras for both Canon EF and Nikon F. Leica's M-mount is another good comparison, as their lenses will fit cameras from Voigtlander and Zeiss, and those companies make M-mount lenses that will work on Leica cameras, too.) The only feature that goes away is the image stabilization in the Panasonic lenses when used on an Olympus body. Okay, there's also a difference in the way they handle automatic chromatic aberration removal - Panasonic does it and Olympus doesn't. I'm not sure if that counts as a lens feature, though.

And there's nothing naive about that viewpoint - having an Olympus body gives the in-camera stabilization, an electronic level (aka 'flight simulator mode', which is awesome for the ultrawides), and the electronic viewfinder for the E-P2 is said to be better than the one for the GF1. But most of the good lenses are from Panasonic; the 20/1.7 in particular is a big improvement over the 17/2.8. Putting the Panasonic pancake on the Olympus body is a great combination, but it's more expensive than just getting one of the kits.

[Toad]

and the electronic viewfinder for the E-P2 is said to be better than the one for the GF1. .

But the EVF for the GF1 is half the size of the EP-2's. I bet it fits with the 20mm and the EVF in my Kata AP-326 (which the EP-2 and its EVF did not).

I have one on hold for me till tomorrow - if my polarized sunglasses work with it - its sold. I will let you know how it goes.

[shuttertalk]

How did you go Rob? Did it work with your sunglasses?

[Toad]

Yes- it works with my sunglasses. Its not an amazingly hi-res viewfinder - but it will serve. Better than what I used to have on my Minolta A2. The nice thing about it is that I can read all the camera settings in it - those things would wash out in bright sunlight before.

[Zig]

This is excellent and superlatively useful stuff guys; Matthew, I sure am glad you don't get out much! Like a spotlight through a fog, mate!

[matthew]

Um, thanks, I think...

[Zig]

Apologies Matthew...it was most definitely a compliment.

[matthew]

No worries, and that's what I thought - and I do need to get out more. :/