Contax N lens to Sigma SA mount conversion with autofocus
What SA mount cameras are supported?Only SD14 is supported.
On all SA mount models prior to SD14, there is a lens detection switch at approximately the 10 o'clock position if you look into the camera mount. Genuine Sigma SA mount lenses have a plastic shroud to trip that lens detection switch but conurus-converted SA-mount lenses do not have that. The camera does not attempt to communicate with the lens electronically if that switch is not activated.
The SD14, however, has no lens detection switch at all and does not suffer from this compatibility issue. Therefore, conurus-converted SA-mount lenses are compatible with SD14 only.
What about SD15 and SD1?We expect SD15 to lack the lens detection switch just like the SD14, but we are not sure and as such we are unable to make any guarantees. The new SD1 has a lens detection switch and is NOT compatible with Contax N lenses.
Are all lenses supported in SA mount?Unfortunately, no. The SA mount has a small opening diameter. The large rear element of the Planar 1,4/85 occupies almost all of the opening and leaves no room for the electrical connector. In some other cases we run into an issue with the mount screw pattern. (It would work if the screw is at the exact same position or a completely different position, but not okay if the screw hole position differs by only half a screw's diameter.)
|Vario-Sonnar 2,8/17-35||Y||SD14 and newer|
|Vario-Sonnar 3,5-4,5/24-85||Y||SD14 and newer|
|Vario-Sonnar 3,5-5,6/28-80||N||screw pattern incompatible|
|Vario-Sonnar 3,5-4,5/70-200||N||screw pattern incompatible|
|Vario-Sonnar 4-5,6/70-300||Y||SD14 and newer|
|Planar 1,4/50||Y||26% chance of success|
|Planar 1,4/85||N||SA mount too narrow|
10% chance of success
|Tele-Apotessar 4/400||N||SA mount too narrow|
|NAM-1||Y||SD14 and newer|
Can I just send my lenses in for conversion?Yes only for the Vario-Sonnar 17-35, 24-85, 70-300 and NAM-1. Our mounts are fully compatible with 17-35, 24-85, 70-300 and NAM-1. For Planar 50/1.4, read on...
An SA mount is slightly thicker than a conurus custom-machined EF mount and requires a certain amount of brass shims to be removed from the lens to maintain the same film-to-flange distance. The thicknesses of brass shims vary from lens to lens and the chance of success of a SA-mount conversion is noted in the above table.
If you send in your Planar 50/1.4 but it turns out that it does not have the necessary brass shims, you will be contacted and we can
- convert your lens to EF mount instead, which is always possible,
- return the lens back to you unaltered, or
- subject to stock availability, we swap your lens with one of our own which has the required shim thickness.
It is also possible for you to check for SA-mount eligibility ahead of time if you have a JIS screwdriver and a micrometer. If you take apart your lens and find some combination of shims inside with 0.3mm thickness, your Planar 50/1.4 is SA-mount compatible.
Please affix a label on each lens with the words "SA mount" to help prevent us from installing the wrong mount on your lens.
Unlike our EF-mount conversion, the rear plastic shroud is not used in a SA-mount conversion and will be returned to you. Again, the SA-mount opening is not large enough to hold the plastic shroud, but if you are a prolific do-it-yourselfer you may be able to cut the plastic shroud until it fits. Not using the rear plastic shroud may potentially increase internal reflection, ghosting and flare.