Metabones EF-RF Speed Booster: non-scientific review

antonio-salieri wrote:

Swerky wrote:

Hello. I’m planning on replacing my full frame DSLR with a mirrorless body while adapting my lenses. I first considered getting an R6 with adapter, but that option might still be too expensive for me. Then I thought of the R7 with a speed booster. I’d save myself a few hundred bucks and possibly get better battery life from the R7.

Especially with the R6ii coming out, the R6+adapter should probably be pretty close in price to the R7+booster. Of course the R6 would be using FF lenses as a true FF camera and without optics (even good ones) in the way. The speed booster can't be used on RF lenses, so the FF sensor may benefit you there too. The R7 has a higher-resolution sensor and can be used for significantly more reach. And there are other differences too. You'll have to compare your options.

I looked on the forum before asking the question and found your informative thread.
Reading the comments, are you saying that the speed booster won’t give the exact focal length as on full frame? Say I have a 24-105 lens, with the speed booster on R7 it will have longer equivalent viewing angles?

Yes. It reduces the crop factor from 1.6 to 1.14, as indicated on the chart. That's much closer to the FF viewing angle, but not quite the same.

And about the bonus fun stuff, I wish you said that there’s an option to keep the lens projecting its native full frame circle unto the APS-C sensor, making a 100mm lens a 160 for example like on a regular adapter, but that’s not even possible given there are optics in the way.

The speed booster always shrinks the image circle to 0.71 times its original size. The option controls whether a FF camera will lock itself into 1.6x (APS-C) crop mode or allow use of the full sensor (which is virtually always bigger than the circle that ends up getting projected after it is shrunken). On an APS-C camera, this is irrelevant, because you only have an APS-C sensor in the first place. A full-frame lens used on the speed booster will always cover your entire APS-C sensor.

It is not possible to use a setting in firmware to change the booster's optics. If you want to use a lens with the 1.6 crop factor, you should use the standard adapter with no optics.

Any clarification concerning the question above is appreciated.
I also found this second more expensive speed booster from metabones. Perhaps a newer one? Seems to do the same thing.

This is a variant of the same adapter with a positive locking mechanism (you need to unlock the mount to put on or take off a lens). This is something some videographers appreciate. The optics and firmware of the speed boosters are exactly the same.

Thanks for the info! An R6 with regular adapter goes for 2400. While an R7 with speedbooster would settle me some 2000, 1980 exactly. But since the speedbooster won't give me the same lens viewing angles as on full frame, then it won't work for me.