Bit of a silly question, and ultimately pretty pointless, but is this even possible, what with flange distances and all that? I'm asking this because I'm in the market for a telephoto zoom, and this would make a 70-200 so much better than the Sigma 50-150.
Unfortunately nothing can really go between EF lenses and EF mount. Speedboosters can be made and fitted because of that flange distance offset between mirrorless mounts (like e-mount, or mft) and mirror mount lenses.
