When adapting EF/EOS lenses to work with your MFT mount camera, you have a few options. Each option has varying price points and essentially attempts to do the same thing which of course is to allow you to use your Canon glass on whichever MFT camera you may own.

The three main types are as follows:

Basic adapter: $20 – $50+

http://www.amazon.com/Fotodiox-Adapter-Olympus-Panasonic-Cameras/dp/B003EAVUMK/ref=sr_1_2?ie=UTF8&qid=1348757624&sr=8-2&keywords=canon+to+m43+adapter

Adapter with aperture ring built in: $80 – $200+

http://www.amazon.com/Kipon-EOS-m4-Adapter-Aperture-Control/dp/B004XGFIZY/ref=sr_1_24?ie=UTF8&qid=1348757693&sr=8-24&keywords=canon+to+m43+adapter

Electronic adapter that controls the lens aperture: $500 – $700+

http://www.bhphotovideo.com/c/product/672332-REG/Redrock_Micro_8_041_0001_LiveLens_Active_Lens_Mount.html

All three adapters have their advantages and specific uses.

The cheaper, basic adapters are all you need if you plan to shoot everything wide open. The point of the more expensive adapters is to give you control over the aperture on your electronically controlled Canon lenses, which for many people is important. If you however have a very fast Canon EF lens, and you only ever find yourself using them wide open and when in a pinch, it may not be worth the additional investment to purchase one with aperture control. I know personally, I have some lenses that I rarely, if ever use stopped down at all. These are lenses I specifically own for ultra low light situations. If you only have one or two lenses and only need them adapted for use wide open, getting a cheap basic adapter is the way to go. If you own a Canon DSLR, one way to deal with stopping down the lens (although quite annoying), is to mount the lens on your Canon camera, set the F-stop and then pop it on to your adapter and MFT camera. That will allow you to change the f-stop on the lens, but every time you want to adjust it you will need to pop it back on your Canon body to make the change.

The the next level up are adapters that have aperture blades built in to the adapter themselves. Essentially they allow you to stop down the aperture through the adapter, rather than actually stopping down the aperture blades that are built into the lens. This is an excellent option for people that mainly need to shoot relatively wide open, but in some rare scenarios may need to stop down. The reason I say some scenarios is because when these adapters are fully stopped down, they often can cause vignetting. This is because the aperture blades are located in the adapter and not in the actual lens where they are supposed to be. With that said, it only seems to happen when you close the adapters down fully, and isn’t an issue on all lenses.

The top tier are the electronic adapters. These adapters essentially mimic what your Canon DSLR is telling the lens to do. Quality wise, these will give you the best image when fully stopped down, as you will not have any issues with vignetting since it is controlling the actual blades within the lens. If you own a lot of Canon lenses and are just moving to the MFT format, this option may be suitable for you. Although they are a bit pricey, you will ultimately be able to use any of your lenses in any scenario with this adapter. Again though, if you don’t typically shoot with your aperture closed down very far, this may be overkill for your needs. The other downside to this type of adapter is that they need to be powered. Either plugged into the wall or some kind of battery rig. This makes the adapters a bit of a hassle to work with on the fly, but still a great option if you are working in a controlled studio type of environment.

When deciding on which adapter to purchase, I ultimately landed in the middle and purchased an adapter with manual aperture blades built it. The reason for this is because I don’t own a ton of Canon lenses, and the ones that I do I nearly always shoot wide open with. I didn’t want to get one of the really cheap adapters because in some scenarios I will want to stop down, and of course I would have no option to do so with the cheaper adapters. I rarely if ever shoot completely stopped down, so any vignetting that may occur when closed down all the way is a non-issue for me. I did consider the electronic option, but it simply wasn’t worth it for my usage. I don’t have enough Canon glass to justify it and don’t necessarily plan on picking up any in the immediate future. I also really don’t like the idea of needing a power supply separately to use my lenses with. Even though I shoot mainly in controlled environments, I still just don’t want that hassle on set. It is one more thing to worry about for no reason as I can easily get away without using it.

So I ended up ordering the Fotodiox adapter from Amazon.com for $80. http://fotodioxpro.com/index.php/lens-mount-adapters/micro-4-3-mft-lens-adapters/fotodiox-pro-lens-mount-adapter-with-built-in-aperture-iris-canon-eos-ef-lens-not-ef-s-lens-to-micro-4-3-four-third-system-mft-camera-adapter-fits-olympus-pen-e-p1-pen-e-p2-pen-e-pl1-pl2-panas.html

I popped it on my Gh2 yesterday with my Canon 50mm 1.4 lens and quite impressed. The build quality of the adapter is not superb by any means, but it doesn’t feel cheap either. It is what you would expect for the price. The iris ring is relatively smooth and on my 50mm lens, there was no vignetting apparent whatsoever – even fully stopped down. Ultimately I was very happy I did not opt to get an electronic version like the RedRock adapter. It simply would have been a waste to consider that as an option as this adapter covers my needs fully.

I have heard good things about the Kipon adapter which is listed above and that one is priced at over double the cost of the Fotodiox at about $180. I haven’t used the Kipon myself, but would assume that what you are paying for is build quality. It may be a more rugged, set oriented piece of gear in comparison to the Fotodiox. I also would assume that the aperture ring may function more smoothly . Although the ring on my adapter is sufficient for my needs, if you do lots of iris rolls while shooting and need a buttery smooth aperture ring, I would guess that you may have a better result with the Kipon.

Overall I am very happy with the new adapter. It does what I need it to do and does it well. One surprise was that unlike the product photo, my adapter does not have f-stop markings. It simply is numbered from 1 – 7 (as you can see in the photo below). It is possible that I was sent an earlier version of the adapter. Nonetheless this isn’t an issue for me as the way in which I will use this adapter will not require me to have the specific f-stop markings on the adapter. It is something to be aware of though if you may need that for your particular style of shooting.

UPDATE: If you’re in the market for a MFT adapter, you have likely been looking into both the GH3 and Blackmagic Cinema Camera. I’ve recently done a quick and dirty side by side comparison of the two cameras that you can check out here.