Metabones EF - M43 Mount (2014) is the long awaited M43 version of the Metabones EF - E Mount, but with some limitations.
The adapter allows to electronically control the iris directly from the camera. Also it is powered by the camera, although it is possible to power the unit externally via Micro USB as well. Like it's NEX siblings, it comes with detachable tripod socket ready for Arca Swiss, Markins and Photo Clam. Image stabilization (IS), electronic manual focusing (E-M), EXIF data entries for focal length, aperture and zoom range are all supported. There is no list of compatible or incompatible lenses (although a list of tested-to-work, which contains a few Canons, a Sigma 18-200mm f/3.5-6.3 and the Zeiss 35mm f/2.0). Simply all Canon, Sigma, Tamron and Tokina lenses and the Conurus Contax N - EF mount conversions will work (may need registration with the adapter first though). As said above, there are some limitations compared to the EF - E mount. At this point AF or Dandelions (focus confirmation chips) as well as features like peripheral shading, color fringing and distortion correction are not supported. In contrary to the Speedbooster there is no word lost on EF-S, but the tested Sigma is a DX lens.
On to pricing. They will charge 400$.
Metabones Speedbooster EF - M43 (2014) is the Speedboster version of the EF - M43 Mount. Like the Speedbooster EF - E it increases the max. aperture by 1 stop, increases MTF and increases wide angle by a factor of 0.71x. The Speedboosters feature and limitations list is otherwise identical to the EF - M43 Mount, except for adding incompatibility with EF-S lenses, although it might be possible to apply some modifications to the EF-S rear parts to make them fit. The Sigma 18-200mm f/3.5-6.3 is still listed as tested compatible straight from the shelf, though that part of the page looks a bit like a possibly faulty copy-paste transaction.
For the Speedbooster optics add another 200$ to the cost of the basic mount version.
MTF Effect (2011) consists of the so called Control Unit, which is wire-coupled to an electronic mount for Canon EF lenses. IS is supported. Mounts are available for MFT, Sony E (NEX and FS-100) and Sony FZ cameras. The original FZ mount was called F3 mount, since with its release in 2011 the PMW-F3 was for long the only camera with this mount (the PMW-F5 and F55 were announced in late 2012). Using the FZ mount results in a magnification factor of 1.5x. The control unit comes with illuminated display to show the current focal length and aperture (both in realtime, even during zoom with lenses not featuring constant aperture values). Aperture can be adjusted in 1/8th stop increments by turning a knob. Mark I of the control unit was powered by AA power cells lasting for a day of shooting. It will automatically shut down when idling to save energy. The only incompatible lens named (as of 2012) was the EF 1.2/85. There was no reason given, but it features E-M, which might be the reason.
In 2013 Control Unit Mark II was released. It is now powered by an external power source via D-Tap or 4-pin Hirose and size and weight were reduced.
In 2014 they aditionally added an EF to AJA Cion mount to their selection. The AJA Cion uses a standard PL mount and comes with a removable front mount plate. The MTF adapter has the front plate build-in, so the adapter will only fit the Cion, not other PL mount cameras.
About pricing ... they charge 650£ for the Control Unit and 350£ per mount (460£ for the Cion). Alternately they also offer dumb mounts, which still go between 200£ and 275£ (415£ for the Cion).
Redrock Micro LiveLens MFT (2011) is an EF mount dedicated to Micro Four-Thirds (digital still or video cameras alike). It allows to control the iris of most EF compatible lenses, including third party products, in increments of 1/3 or 1/2 stops. The unit weights 122g and is powered by an external 9V battery pack (adds another 85g and lasts for 20h of operation). The Redrock Micro LiveLens MFT is not compatible with the Redrock M2 Encore or M3 Cinema Lens Adapters ... check Dedicated Lenses > Adapting EF > EF to Misc Mounts for their LiveLens Active Lens Mount.
"Additional lens features that require power may not be supported." (Redrock article page - description)
"Currently the LiveLens MFT [...] does not provide power for image stabilization." (Redrock article page - FAQ)
"LiveLens mft [sic!] does not power focus by wire lenses like the 85mm f/1.2 and 300mm f/2.8. It also does not work with Canon or third party teleconverters, extenders, or macro tubes." (Redrock article page - FAQ)
<rant>Alright, I admit it ... I never got the point why people would rave about Micro 4/3 when I just couldn't stand to wait for Canon to release a high ISO full frame DSLR any longer. Micro 4/3 actually seemed like a bad joke to me, because at the time of it getting established on the market, most people were already swearing about the near end of even APS-C sensor sized consumer DSLRs. Lots of especially spare time photographers wanted bigger sensors for higher ISO, less noise and less crop to finally use those wide angle lenses properly again, that were left in the shelf since the end of analog times, leave alone a minimum camera size required to come in handy and balanced with lenses. So why Micro 4/3? And hey ... here we go with just another bad joke ... and guess what? It's Micro 4/3 again, although not genuine. This is really pretty weak ... a 550$ adapter, that is - if at all - interesting for film makers, but doesn't support IS (nor AF) and I guess every change of aperture will cause numerous events of camera shake, since the touch pad to change the value is fixed to the adapter and you have to go through all the stop steps until the desired aperture is set. Communication of lens data to the body? Nope. And yeah, the Redrocks aren't even bothered to set up an exactly detailed product page. It's all achieved by magic. Reading the small print section you'll note, that you have to order the battery cable separately for another 50$ and that RrM doesn't mention the format of the required battery, that - wuh-huh - comes with the cable (might well be some proprietary format, that you have to order with the cable every 20 hours of use. Also not a single word about EF-S is lost. I'd guess it's not supported, but in fact is reported by users to work flawlessly. And what do we have there? Focus by wire lenses? Hmm. Welcome to the world of Canon EF! I guess the term these guys were looking for is Electronic-Manual. WTF.</rant>
Finally watched their fancy video tutorial ... the "cable" actually is a wired battery pack housing an exchangeable 9V 6LR61 standard battery block (available in 1.2A max.). And there even is an option to power the mount via so-called "D-tap power cable" (no clue what connector it has on the opposite side of the D-tab) connected to an IDX Endura 10s Li-Ion power pack (14.8V, 6.3A).
Due to pricing, handling and/or additional bulk the adapters listed here (with the exception of the Metabones) I'd rather consider worthy for cinema applications than for still photography. Have a look at Mirrorless Cams > EF Lens Adapters for a list of adapters primarily focused on photography. Included are Canon EF-M, µ4/3, Sony E and Fuji FX mounts.