I have the Canon 17-55mm EFS 2.9 that I really like. I'm hoping that it works good covering 4K. I also have some non Ai Nikons that I will be experimenting with. I really like my Nikon 50mm 1.4. I ordered the Canon mount but I don't think I'll be buying any more lenses before I get my Scarlet. I may decide later to go with the PL mount and goes with the Red 17-55mm and the 85mm prime.