@DrDave "Yes, of course, I doubt that m4/3 have a circle large enough--although I guess one could use them in etc mode for yet another look." It's not only the image circle that won't make it work, it's the fact that m43 lens' are designed for a backfocus distane for m43. Adapters like this, and any adapter for SLR lens' are using the fact that the backfocus is shorter for mirrorless cameras, and make up the difference with the adapter its self. Besides image circle size, you can't add an adapter between a m43 lens and body and expect it to work unless you're only interested in macros.

@Stonebat ...as someone already said, the Sigma 20mm/1.8 is an exciting possibility. It's a little bit mushy, but bright, wide open on my GX1s. It's plenty sharp on APSC and FF though, so I'm betting it'll be killer as a 28.5/f1.2.

@shian yeah, this is going to be a big deal for all the film rigs in general, since they're all smaller than 135 FF.

This is a better solution for video for 70-200 lenses on the Panasonic cams in my opinion. The 35-100 has no been getting stellar reviews and the zoom and mechanical focus on the FF lenses are much more luxurious to use. I'm ready to order ASAP!

I have one prediction.

As it is widely known F stop and focal lengths talks are most popular flame topics. This thing will add fuel to both :-)

Considering the 1000$ price of original Canon's adapter FD to EF with top IQ optical elements, this thing is much more interesting.

It turns micro4/3' effective crop to 1,32 and who doesn't care for the electronical coupling but does about money can get in $400 adapter FD to micro4/3 excellent solution:

-FD lenses are among SLR lenses with shortest distance to the film (somebody help me with the particular name for that distance- there is one) so with supplement of several cheap mechanical adapters, it should be possible to use nearly all Pentax, Minolta, EF, Nikkor and Zeiss with this single adapter.

Correct me somebody if I am wrong please.

What happens to t stop with this adapter?

Minolta Rokkor lenses will need their own version of the Speed Booster. The flange distance of a Rokkor is 43.50mm and the only smaller flange distance version of the Speed Booster listed in the white paper is the Alpa adapter. The Alpa has a flange distance of 37.80mm. This would mean that you would have to find a Rokkor lens to Alpa body adapter that was 5.7mm thick. I don't think there is one that has been made, and I don't know if it can be made.

There are Minolta Rokkor (43.50mm flange) lens to Nikon F (46.5mm flange) body adapters with a built in lens to attempt to overcome the mismatch of putting a smaller flange distance lens on a longer flange distance body. From what I have read, this is not a very good solution.

Hope someone can think of a solution. Would love to use my Rokkors with the Speed Booster and my GH2s.

re: Rokkors -

http://www.4photos.de/camera-diy/minolta-rokkor-58-to-canon-eos-conversion.html

Easy conversion for a 58mm 1.2 to EOS (I'm assuming this would mount on the metabones adapter)

@soundgh2 Very interesting, but really not what I want to do to my glass.

@christianhubbard Wish I could help. Hopefully the good folks at Metabones will tell us if the optical design will accept this combination. Seems like it would.

I am not an optical engineer, but here is what I guess might be going on (at least I hope so):

It seems like the reason they are making an ALPA Speed Booster is because ALPA has one of the shortest flange distances among the shuttered brands of cameras, 37.8mm. This allows them to make adapters for some of the longer flange distance cameras. In my case, the Minolta SR mount (MD,MC) is 43.5mm. As I stated above, I would need an adapter that was 5.7mm thick for the lenses to work. In order to use my Nikon F lenses (46.5mm), I would need an 8.7mm thick adapter.

I really don't know if this thinking is correct. I have sent an email to the good people at Metabones asking about this theory and will let everyone know what I hear back.

@tetakpatak @DrDave ...and sadly, the white paper does not list plans for a Speed Booster for Canon FD lenses, only Canon EF lenses.

@fredfred27 alternatively -

http://www.amazon.com/Minolta-Canon-Adapter-Focus-Infinity/dp/B005JRCWI2/ref=pd_sxp_grid_pt_0_0/182-5350953-7831146

http://www.fredmiranda.com/forum/topic/748982/0

Interesting read about flange distances etc

http://digitalrokkor.altervista.org/techdetails.html

58mm 1.2/1.4 specific

And Jim Buchanans non destructive user installable mod for 58 1.2

Also Leitax's v easy mod

http://leitax.com/Rokkor-lens-for-Canon-cameras.html

I wouldn't like to butcher any of mine either :)

There are adapters from Minolta SR to Sony Alpha, but hey use a lens which is degrading the quality.

I am very excited about this development. With metabones showing a clear preference to e-mount over m4/3 I think this might bring more interest to the sony format and hopefully we will see more innovative products for the mount as a result. And I hope this might bring more eyes and developers to the Nex hacking project.

IMO I don't think a m4/3 version will be seen very soon. Metabones seem to be prioritising there efforts for the e-mount system due to the fact that just about every fs100/fs700 user considers the metabones as a go to adaptor (most having moved from using 5d's and 7d's as professional tools, and having built up a selection of canon glass). I think demand for the emount version will be so strong from the fs100/700 users they won't have enough manufacturing ability or see a need to go into manufacture of the m4/3 version due to the income generated from their current core user base. What with the abundance of fast/wide lenses specifically designed to cover the m4/3 format, and the complete opposite situation for the e mount system i see this as another reason the demand for nex adaptors might lead to a slow or non existent m4/3 version of this.

@richg101: From one of the developpers, on another forum: "Passive MFT will be added in March 2013 for Leica R, Alpa, Contax C/Y, Contarex, Rollei and Nikon (including DX and G). An active MFT for Canon EF is planned for the future."