Amedeo Muscelli
Established
Hello Jon,
Contax and Nikon use the same helical pitch.
Amedeo.
Contax and Nikon use the same helical pitch.
Amedeo.
Thanks Amedeo! I always expected it was the same, but its good to get confirmation from an expert!
Jon
Jon
Rayt
Nonplayer Character
I have a limited edition ZM 50/1.5 Sonnar for Nikon RF and it focuses perfectly at max aperture and minimum distance on the M7 with the Amedeo adapter.
angeloks
Well-known
Ok, I got my answer from the eBay seller :
"This adapter is mainly designed for contax RF lens to L39 mount."
Now we need to convince Amedeo to make some Nikon to L39!
"This adapter is mainly designed for contax RF lens to L39 mount."
Now we need to convince Amedeo to make some Nikon to L39!
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Hmmm there was an excellent (as always) post by highway61 here that now seems to have been deleted.
Anyway, the content of the post was that although both the Contax helical and the Nikon helical have the same thread pitch, a Nikon helical cannot be used on a Contax camera (or visa versa) just by shimming it. The reason is that the Nikon helical needs to rotate about 280 degrees to focus the lens from infinity down to 3 feet, and the Contax helical needs to rotate the about 290 degrees to focus the lens from infinity down to 3 feet.
It's this difference between the amount of helical rotation required for focus at a given distance that causes the incompatibility.
This causes a Contax lens to back focus on a Nikon camera, and a Nikon lens to front focus on a Contax camera. Depending on the aperture and focal length used, the DOF may or may not cover this inherent focus error.
Anyway, the content of the post was that although both the Contax helical and the Nikon helical have the same thread pitch, a Nikon helical cannot be used on a Contax camera (or visa versa) just by shimming it. The reason is that the Nikon helical needs to rotate about 280 degrees to focus the lens from infinity down to 3 feet, and the Contax helical needs to rotate the about 290 degrees to focus the lens from infinity down to 3 feet.
It's this difference between the amount of helical rotation required for focus at a given distance that causes the incompatibility.
This causes a Contax lens to back focus on a Nikon camera, and a Nikon lens to front focus on a Contax camera. Depending on the aperture and focal length used, the DOF may or may not cover this inherent focus error.