I recently decided to make the switch from a Canon DSLR to a Canon R mirrorless. It was easy to learn since I'm already used to Canons. I bought the EF to RF adapter (with the adjustable ring) so I could use my DSLR lenses with it. My only complaint is that Canon should give you the adapter free (they used to!) when you buy the camera. So far, it's taking good photos, and I decided to buy the kit lens that goes with the camera, so I can use it for all-around use when I'm out and about. I have a very nice Sigma macro lens that I bought at the same time, which needs the EF to RF adapter, but it takes very nice macros on this camera. I'm glad I bought it.

I purchased this adapter along with the EOS M camera kit to use with my EF and EF-S lenses. After less than a week, I have been able to try out with the EF 50mm F1.4, EF 70-300mm L, EF-S 17-85mm, and EF-S 60mm lenses. The adapter fits perfectly. Same form and fit as the Canon extenders I have. The EOS M is of course made very tiny with any large EF lens. It creates a sort of 'pocket Rebel'. Of course, once you mate with the larger lens, this is no longer going to fit in anything less than a massive coat pocket. The combination of camera, adapter, and lens seems comfortable after brief handling. The EF 50mm was a very comfortable combination, the adapter does not add a very large amount to the overall combination. The upside to this adapter is if you already have a variety of EF and/or EF-S lenses. The image quality of the JPEGs, right out of the camera ranged from expected to stunning (the latter results obtainable with off camera studio flash strobe and soft box). The adapter was immediately a huge part of the EOS M camera purchase. I highly recommend it if you have other lenses. Again, the results I got with the EF-S 60mm macro (and studio lighting) were stunning. It transformed the camera from curiosity to studio prime. No problem using manual mode and Pocket Wizard. Include this adapter in your purchase and you won't be looking back.

I've used my EF 100-400 with an RF adapter. It's good but as someone older, this RF lens is light, compact, and is optically sound for my purposes. I also own a 150-600 Sigma which usually needs a pod to hold steady and I've missed more shots than I've captured with it. This RF 100-400 is great for me; it so easy to pan while shooting birds in flight!

Good lightweight camera. Great value and with lens adapter I can use all my EF lenses.

What a beautiful lens at a fantastic price. I’m using it in conjunction with an ef-m adapter and speed booster which opens it up to F1.2 which is insane for the price. Love it! It’s truly the nifty-fifty!

I love this adapter, metal construction and a build worthy of L lenses. I have been using this adapter with the 70-200 f4l and it is a joy to use, it has a quality feel befitting the L series lenses and a finish that matches, back up a bit and you wouldn't really notice there is even an adapter attached on the non-white lenses. balance with the M isn't a problem for me, I shoot holding the lens where it meets the adapter and can easily turn the zoom and focus rings. with the tripod mount attached it is unobtrusive enough that I never notice it's attached and therefore never need to remove it. Being OEM the transmission of lens data is seamless, the lens might as well have been built for the camera in the same way as any EF or EF-S lens is for an APS-C camera. When using this adapter the EOS M gets all the information its big brothers do, as such the in camera aberration and vignetting correction that is assigned to each lens works just like it is supposed to. With the L lenses mounted to the M with its digic-5 processor the image quality is first rate for a canon aps-c camera and with the magnesium alloy construction of the body together with this adapter the feel is above and beyond consumer ranges like the rebel and fit right in with the prosumer cameras like the 50D and 7D (not like the plastic of the 60D )Overall it is an adapter, but a great one the likes of canon converters... It just works, day after day.

The adapter is good, delivery was also very fast, i got it just in 1 day.. But if you really wanna use EF or EF-S lens in mirrorless cameras, you have to keep in mind that the sharpness will decrease by a little amount and you you have to focus the subject very correctly, otherwise the picture will become blurry(specially for the prime lens)..

So you finally decided on getting the EOS M (it's flaws considered). I assume you are a canon user, have a couple of good (canon EF/EF-S mount) lens lying around and would like to be able to use those on you EOS M. Just like me, you love your canon dslr but sometimes wish you can travel light but still be able to enjoy the canon ecosystem that you have grown to love. If you are what I assume you are, get this lens adapter.I took a gamble and bought a "like-new" used from a seller at Amazon and was very happy with a purchase. For anything more than $150 I probably would think twice. But I am not taking a start out because of the price. This adapter handles every canon mount lens I threw at it. The build quality is nice. The design (the way it attaches to the eos m; the included, detachable tripod mount) is well thought of... just perfect.