My YKEASU (odd name I know) RF/EF adapter from Amazon arrived today and its alright. Autofocus speed seems a touch slower than first party but otherwise it's identical in form and function. It even has the rubber gasket for some weather sealing. I'll tell you after manual focusing and focus peaking -- both very good and methodical don't get me wrong -- autofocus feels like magic. Point and shoot. Wow. Though I will say the 40mm looked a little underwhelming to me, as did the 75-300mm. Maybe crop sensors DO expose the best parts of the lens, and my full frame format is just showing more of the flaws, or I'm just not shooting with enough light ... Meanwhile, my 24-70mm is arriving Monday. I'm trying to forget about it and keep my expectations reasonable.
"[Growing up] is hard and nobody understands." // https://www.homestuck.com/story/2391