I have a canon 600d and am looking to upgrade soon, probably to a gh4 or a7sii. My question is how would my lenses translate to either camera in terms of fical length, would the auto focus still work and would i need a speedbooster? I've tried reading about it but im confused! Two example lenses I use a lot are the nifty fifty canon 50mm 1.4 and the sigma 10-20 4-5.6f wide angle tele. Thanks!