But will I.S. and AF work on the m4/3 camera version like it does with the Sony cameras? I would gladly buy this if I can use my Canon lenses with aperture control and I.S..

It's the same principle as a magnifying glass, just not as extreme. Reducing the area over which the light is spread amounts to making it brighter.

Well presumably the focal reducing elements in those 2 lenses were designed specifically for those lenses. This thing from Metabones is supposed to work with basically any lens, which is a whole different ball of wax.

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E-M5 | E-PM2 | mZD 12-50 | ZD 12-60 | P 14-42 X | mZD 40-150 R | PL 25 | mZD 45

So I don't understand why people seem to doubt this so much; even though it does sound "magical", it's just clever physics.

Very simply put, if you take a certain amount of light and compress it into a smaller area, you are going to have more light in that area. The light is "denser", and therefore brighter. The magnifying glass is one extreme example of this. Essentially the same "total" amount of light, you just aren't wasting light that is cropped off by the smaller sensor size.

Metabones has a good reputation as far as I know. Looking at the product description, the glass is manufactured by "Caldwell Photographic", which a quick google search shows as dealing with large format glass and specialty products, and seems pretty reputable.

Honestsly, I think the high price tag is good rather than bad. It means it's more likely to be a good product. For the video folk, where size, AF, and perfect optical quality are lesser concerns, this seems like a wonderful option.

You also may wonder why no one has done this before(although as others have pointed out, the concept has been applied in different ways). Simple: this is only really possible on mirrorless cameras. You need to use the reduced space from the decreased flange distance in order to accommodate the reducing optic.

I don't really see a reason to doubt it will work well with most glass. It will pretty much never be exactly as sharp or bright as the FF lens would be on an FF camera thanks to the extra element(unless it luckily works in a complementary manner with the other glass), but assuming a decent optic it will certainly be sharper than the same glass mounted on a smaller sensor camera without a focal length reducer. Or well, at least in the center. Lenses with really bad corners that might be cut off by a crop will show off this flaw once more. Same with vignetting.

Regarding brightness/speed... Well, I've always thought T numbers were better than F numbers anyway, since they give you a more accurate assessment about how bright the image will be. If the aperture "speed" of this lens is increased by one stop using this FL reducer, it will probably lose a litttleee bit of light(T-value) relative to the aperture thanks to the extra glass/coatings, but I highly doubt it will be anything significant. It's just one element.

In any case, look at the video samples. We don't know about stills yet, but I certainly see no loss of image quality based on the videos.

I just wonder when the Ebay cheap imitation will arrive.
An all manual adapter like this can be very attractive on old manual lenses.

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Cameras Panasonic G5 and G2
lenses Rokinon 7.5, P14-42, P14-45, P20, P45-200, P100-300
Adapted lenses Olympus 50mm F1.8 OM , JCPenney 135/F2.8 OM, Teleplus 2X MC7 Macro

http://www.flickr.com/photos/ehudlavon/

Please correct me if I'm wrong:

If for example I used a canon FD 50mm lens with this kind of device (I know it doesn't exist for µ4/3) on my epl3 I would get a focal length equal to a 25mm native µ4/3 lens?
I understand the actual focal length would be the same regardless but the equivalent would be 25mm, because it now would be projecting the 50mm FF image without being cropped so would equal 25mm?

Or have I completely lost it?

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EPL-3 | VF-2
40-150 R | 14-42 II R | Sigma 30 | Samyang 7.5
Expert 135 2.8 | Prinzflex 70-162 3.5 | Helios 44-2 58 2.0 | Canon FL 50 1.4 | Konica Hexanon 50 1.4 | C-Mount 35 1.7 & 25 1.4

I believe this is a 0.71x converter, so you'd end up at 35mm, but a stop faster.

As the above poster said, it's a 0.71x converter.

If you wanted something close to 25mm, you'd have to look for a 35mm lens, which would be brought down to 24.5mm. It's a shame because it's easier to find fast 50s than 35s, but still quite cool nevertheless.

I have just finished reading the white paper. It looks very promising technology that will add significant advantage to the mirror less cameras. I suggest reading it especially the application and example parts.

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Cameras Panasonic G5 and G2
lenses Rokinon 7.5, P14-42, P14-45, P20, P45-200, P100-300
Adapted lenses Olympus 50mm F1.8 OM , JCPenney 135/F2.8 OM, Teleplus 2X MC7 Macro

http://www.flickr.com/photos/ehudlavon/

Interesting stuff.

I'd be interested in this adapter, IF I had some nice L lenses, that cost point is a bit of a deterrent.

Interesting, but I'd say it's a couple of years too late. Other than long teles (where you probably don't want the reduced the focal length, m43 now has a very good lineup of both primes and high quality zooms. I sooner buy a 25mm PL 1/4 than use a 35mm f 1.8 and this converter. While the converted lens might be faster, it will also be much larger and heavier and more expensive when combined with the converter.

And it certainly won't AF, and we don't know if it will provide aperture control for lenses without aperture rings.

For a photographer with a large collection of legacy glass who doesn't care about AF, this may be an effective tool. For most m43 users, I think it's an interesting novelty, and $600 is a lot to pay for "interesting."

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I'm not lazy. I'm energy efficient.