T.Dascalos
Not Available
Had a research on a solution for C645 (me among them) users to go wider... The Pentax 25mm f4 lens with a 6.87mm spacer will work on the Contax exactly the same as it would on a Pentax 645 camera, the lens will also work on M645 mount with 7.57mm spacer and will also be compatible with the Leica S cameras with additional spacing added.
Of course, this means that all Pentax 645 lenses can be fitted on the same MF cameras, but with the new 28-45mm f4.5 and the 25mm f4 attracting special attention to C645 users as they can't go wider than 35mm with what was available up to now.
The aperture control of the lens is fairly easy to adjust as Pentax D & DA lenses use mechanical coupling via a lever on the lens mount flange which works much the same as it happens with Nikon G lenses which also don't have an aperture ring (but aperture coupling is still mechanical).
I'm thinking to build the adapter by saving off the back of a Pentax 645 old extension ring and add a C645 lens mount to the back of it out of a Contax extension ring. To control the aperture, I'll use a thin (1mm) ring machined so that its inner diameter "just" fits on the outer diameter of the (what used to be) the Pentax extension ring and connect it through a slot with another thin ring to the inner diameter of the same spacer, that will have a small extension at the same place as the Pentax 645 camera mount has the lever to automatically adjust the aperture of the lens. (Any other suggestions on the matter are welcomed)
As of AF... who needs it on a 25mm f4 lens?
Of course, this means that all Pentax 645 lenses can be fitted on the same MF cameras, but with the new 28-45mm f4.5 and the 25mm f4 attracting special attention to C645 users as they can't go wider than 35mm with what was available up to now.
The aperture control of the lens is fairly easy to adjust as Pentax D & DA lenses use mechanical coupling via a lever on the lens mount flange which works much the same as it happens with Nikon G lenses which also don't have an aperture ring (but aperture coupling is still mechanical).
I'm thinking to build the adapter by saving off the back of a Pentax 645 old extension ring and add a C645 lens mount to the back of it out of a Contax extension ring. To control the aperture, I'll use a thin (1mm) ring machined so that its inner diameter "just" fits on the outer diameter of the (what used to be) the Pentax extension ring and connect it through a slot with another thin ring to the inner diameter of the same spacer, that will have a small extension at the same place as the Pentax 645 camera mount has the lever to automatically adjust the aperture of the lens. (Any other suggestions on the matter are welcomed)
As of AF... who needs it on a 25mm f4 lens?