I bought this adaptor for an old manual focus Vivitar Series 1 90mm Macro lens. This is a superb lens for film or digital and I wanted a lens adaptor which was economical but would work smoothly and retain as many functions of my Canon cameras as possible.I tried a Fotodiox adaptor but the fit was very rough and too snug on my Canon EOS 5D Mk1. And on my Canon EOS 650 35mm film camera it was too loose and would not let the meter read properly. All I got was an "EE" total error. So I took the FOTODIOX back for a refund at the camera store.I found this adaptor by K&F. I don't have any other lens adaptors from this company but heard good reviews. It's a little more than the FOTODIOX. But at only $5 US more it fit my budget. When it arrived I first put it on the EOS 5D body. Perfect fit! Snug and smooth. And more important it UNmounted just as smoothly. Fotodiox product was difficult to remove. But the K&F came off like a Canon lens should.Then I put the Vivitar Series 1 lens on the adaptor. Also perfect! Focused to infinity and perfectly at very close Macro distances as well. Av and Manual mode metered perfectly as well, measured against my Gossen Luna Pro handheld meter.I next mounted both on my 1987 Canon EOS 650 35mm film camera, which I've had since it was new. I still shoot a lot of film for its unique look. I was surprised that the K&F adaptor went on smoothly and retained Av metering-even in Spot mode on this first EOS camera ever made! I like this adaptor so much I'm tempted to replace many of my Fotodiox lens adaptors with their brand. In any case I know that any new lens adaptors I purchase will be made by K&F