VILTROX EF-M2 II Electronic Auto Focus 0.71x Reducer Speed Booster Lens Mount Adapter for Canon EF Mount Lens to M4/3 MFT Camera PEN-F GH5 GH4 GF9 GX85 E-M5 E-M10 E-M10II E-PL3

I'm using this little Speedbooster for my Blackmagic Pocket Cinema Camera 4K. I love how the crop factor compared to full frame decreased from 1.9x or 2x with the 4/3 sensor, to about 1.33x with the Speedbooster. I am used to shooting on APS-C cameras, and this gets me a little wider shots with the same lenses, without being drastically different to what I'm used to.The fit onto my BMPCC4K is snug, and there is little to no wiggling around, except a very tiny bit of rotational play, which is mildly annoying when zooming/focusing with stiffer lenses, but not really noticeable in the image most cases. It feels solidly constructed.I mainly use manual lenses, but the electronics do allow me to control the aperture on my Canon lenses, and the display even takes into account the equivalent aperture based on the speedbooster.I haven't successfully used any autofocus or image stabilization features on my Canon lenses with this adapter yet, and my BMPCC4K doesn't seem to recognize that image stabilization is available at all for Canon lenses. However, I read in a forum that a firmware update of the speedbooster could enable image stabilization with my camera.Unfortunately, there is no way to use Canon EF-S lenses with this speedbooster - they are designed for a 1.6x crop factor anyway, and wouldn't look right on the equivalent of a 1.3x crop. But because of the longer flange distance of EF-S lenses, they will not physically fit this speedbooster - or many other EF mount adapters in general. Just keep that in mind, as you plan what gear you're purchasing.One neat trick I've done is to use EF macro tubes (with electronic contacts) on my EF-S lenses, which allows them to be used with the speedbooster and maintain electronic aperture control. You lose the distance/infinity focus because of the macro tubes, but the EF-S lenses will work for specific situations with this setup.The one problem I've had is that I can't really use any of my lenses wide open - Rokinon primes, Rokinon Cine DS Primes, adapted Tamron Nikon-mount zooms - they all have a lot of "bloom," where the lighter parts of the image appear hazy and never quite in focus when the lenses are at their widest apertures. But stopping down a little clears this problem up, and with the ISO capability of my BMPCC4K, I am not quite as concerned about the loss of light from stopping down a bit.The build quality is quite nice - the optics of the speedbooster lens(es) inside the adapter are quite sharp and don't degrade the image much to my eye. If you are having problems achieving infinity focus using this adapter, the glass elements inside can be carefully rotated to adjust their distance from the lens/image sensor. This can be done with careful fingers, no tools required.Overall, this is a great budget alternative to a Metabones speedbooster!

This adapter is absolutely amazing. In combination with the new GH5 focusing system, its phenomenal with a focus and quality. The ability to change aperture, find focus and its magnification makes any canon lens amazing. My issue is that during recording the autofocus hunting is noticeable audible. Also the autofocus for the camera needs to be tweaked, not really sure if that is the adapters fault. Either way it can be updated so I expect a fix to come. Otherwise good value and amazing performance.

Great if you want to save a ton of money. I needed this for my black magic 4K cinema camera. I didn’t want to spend $600 for a metabones. This was the perfect alternative! Works fine. Only issue is that the infinity zoom, you have to manually rotate but once that was done , it worked great!

This speed booster is pure garbage and an example of, ‘You get what you pay for,’ which is certainly the case here. When attempting to attach this booster to my Sigma 18-35, it felt like the lens was going to bust apart due to how much pressure I was putting on it. I knew that was a bad sign then. It finally clicked in and soon I was using my Sigma on my BMPCC4K. However, the results were not ideal and arguably not usable especially when making a film. So, I thought maybe it was a firmware issue. I plugged this booster into a micro USB cable and it did not connect to my iMac or PC. Then I proceeded to use 7 more micro USBs to the exact same result. Nothing. At that point, I just decided to return it and hope the Metabones is better.

Mine failed after 6 months of use with a sigma lens. It began making a buzzing noise and no longer would communicate to the camera.