I'm receiving my EOS R this week ($1299 at B&H with the private coupon code - no brainer!) -- so this video came in at the perfect time. I wonder, how would a Sigma 18-35/1.8 plus this speedbooster work with the 1.74x 4k of the EOS R? Would the 18mm vignette? What would the usable range be, and in FF equivalence?
And at $479 that's a lot less than their usual $600+ m43 to EF speedboosters. I wonder if they'll come out with a .64x "XL" speedbooster like they do for m43 -- that would get us to 1.11x crop!