Brian Caldwell who designs the optics for the Metabones Speed Boosters is one of the unsung heroes of the modern world of photographic gear for me. Simply because of what he has made possible for photographers (and videographers of course) And things are still moving forward. I've got one of the above hopefully arriving in a few days and it's the latest version with a x0.64 crop. Which means that with my Nikon 20mm f/1.8 G lens I will now get a 35mm / 'full-frame equivalent of a 26.5mm on my m4/3 cameras using the above adapter. As opposed to around 30mm that I got with the previous x0.71 one and of course 40mm with an ordinary adapter. Add in the fact that every aperture I select on my adapted lens lets in one stop more light with the adapter than without it and you can see how useful it is.
There is also a factor in the way that it works that has other advantages. While most adapters are often considered as making the image worse, the Metabones Speed Boosters can be seen as actually improving the image quality. Because the speed booster is taking the input from a 'full frame' lens and focusing most of that onto a smaller 4/3 sensor, it can be seen as much the same as downsizing a large pixel count image into a smaller one. There is more 'optical information' to start with, which should result in better quality and better resolution.
The reality is however that suddenly all sorts of lenses become more useful on m4/3 cameras. One of the reasons I got involved with m4/3 in the first place was the fact that I could use my Nikon and m-mount lenses on my Panasonic and Olympus cameras. However that was tempered by the fact that the 2x crop factor the 4/3 sensor imposes meant that I got some spectacular telephoto options (My Nikon 85mm becoming in effect a 170mm f/1.8 lens) but wide angles were a problem. There aren't an awful lot of usable 35mm / full-frame lenses with less than a 12mm focal length. But the first Speed Booster with it's x0.71 crop factor meant that lenses had a focal length equivalent to that when fitted onto an APS-C sensor camera. And now the x0.64 version gives approximately a 1.3 crop factor for m4/3. A 14mm performs (all approx.) like a 19mm lens, a 20mm like a 26.5mm lens and a 35mm like a 46.5mm lens etc. So it's now possible to keep a full-frame wide-angle lens as a wide-angle lens on m4/3 cameras., with only a small loss in wide-angle capability. I've just ordered myself a Nikon fit Samyang 14mm f/2.8 lens, which will give me the approximate full-frame equivalent of a 19mm f/2 lens. Very useful. It also of course works on my DSLR's and Leica T as well.
Just to clear up one thing. When I and others talk about Speed Boosters changing the maximum aperture, this is only in terms of light gathering. The Samyang lens is still an f/2.8 lens. I just get a stop more light with the speed booster than without it. For example if I was composing a shot that gave me a reading of 1/30th. sec at f/2.8 and ISO 400, using the speed booster means that I can take the shot at either 1/60th. sec at f/2.8 and ISO 400 or 1/30th. sec at f/2.8 and ISO 200. Both alternatives giving me a 1 stop improvement. So as you can see, this improves m4/3 ISO performance by one stop. So in situations where I'm working in low light I can use ISO 1600 instead of ISO 3200, ISO 800 instead of ISO 1600 etc. or a faster shutter speed if that's more important.
All of this is of course manual focus, though if you use Canon AF lenses Metabones have an adapter that does autofocus, though it's quite slow I gather. However, with the excellent manual focus implementation on Panasonic cameras this is not really that much of problem for what I photograph, though with Olympus cameras it requires a bit more button pushing.
So like the Olympus high-res mode this is stretching what m4/.3 is capable of and cancelling out the disadvantages that some would perceive the format as having. High-res mode offers a very high pixel count and the Metabones Speed Booster x0.64 offers almost 'full frame' parity with high quality 3rd. party lenses and makes them 'faster' as well. And I'm sure if it's technically possible we may well have a x0.5 speed booster which will give 1:1 parity for 'full-frame' lenses on 4/3 sensors before long. And this is the second reason why I think the future for the m4/3 format is very bright and very exciting in terms of what it offers, both for stills and video. I have no issue with DSLR's and often I enjoy that 'big camera feel' but the opportunity to get equivalent or better image quality from the smaller m4/3 system is something that I'm very happy to take advantage of. Despite my reservations about the DSLRisation of mirrorless cameras it can't be denied that they and m4/3 in particular ARE smaller and lighter than DSLR 'full-frame.'
Nearly six years ago I was writing about my desire to use m4/3 as my 'pro system' - http://soundimageplus.blogspot.co.uk/2009/10/g-series-pro.html - and after all this time it may well be becoming a reality. Shame they don't still make those red cameras though!!