I have used ZM lenses on my Leica M4, and ZF lenses (21/2.8, 35/2.8, 50/2, 100/2.8) on my Nikon F5.There are amazing! It's not just sharpness and contrast that are outstanding, but just the way they render the scene being photographed. I had used Leica lenses in the past, but Zeiss beats them...