EF to RF Metabones 0.71x Speed Booster (review)

[navastronia]

I had no idea Metabones was working on this. I probably won't buy one because I don't do much video (and I'm never in APS-C mode shooting stills - why not make a medium format lens speedbooster to use on 35mm sensors, instead?) but the performance isn't that bad outside some apparent softness at when viewed at 500% (see 09:49).