Aaton to Nikon Adapter not fitting Aaton Camera

[M Joel W]

I bought an adapter from someone on this forum (traded for it) and forgot to see if it fit on my camera. Which I should have. 

It doesn't quite seem to fit. The three prongs don't go low enough to lock the mount. My other lenses and Aaton adapters are all okay.

Should I bring it to a machinist to machine down the sides of the prongs? Which I assume are the issue? Or just sell it here really cheap/give it away? Is this a common issue? Any way to fix it?

Thanks!

[Robert Hart]

Is it by any chance a Nikon F-Mount to CP-Mount adaptor with a small planar glass element inside? Aaton Mount and CP-Mount apparently have some similarity but the Aaton shoulder diameter may be wider. 

[M Joel W]

I don't believe so. No glass element inside and it's a very close fit, just feels a little too tight and kind of gets stuck in the mouth and the positive lock won't lock.

It fits into an Aaton cap. 

[Tyler Purcell]

Very odd, I had one that fit perfectly. I wonder if it was somehow damaged. 

[M Joel W]

It's odd – I measured it with a caliper and everything seems to be about the same as my other Aaton mount lenses, at least close enough. I wonder if just shaving down a little bit here or there might help. But it's hard to say.

[Dom Jaeger]

So is it the thickness of the flange wings that is out, so the lock ring won’t turn over them? Or the mount won’t seat properly?

On PL mounts, the flange wing thickness needs to be within about 0.05mm of the nominal size for the lock ring to properly lock. Manufacturing errors, a burr or distortion due to being dropped can cause problems. The front surface of the flange wings (not the rear, seating surface) can be lathed down if necessary.

There can also be potential issues with the chamfer around the lip of the camera mount and the right angle cut of the lens mount where the rear cylinder goes inside the camera mount. If there is too much of a rounded corner on the lens (or adapter) mount it may not seat properly. I’ve sometimes had to lathe an undercut on cheap PL mounts so they seat properly.

Unless it’s distorted a machinist should be able to fix the issue.

[M Joel W]

On 5/1/2024 at 1:19 AM, Dom Jaeger said:

So is it the thickness of the flange wings that is out, so the lock ring won’t turn over them? Or the mount won’t seat properly?

On PL mounts, the flange wing thickness needs to be within about 0.05mm of the nominal size for the lock ring to properly lock. Manufacturing errors, a burr or distortion due to being dropped can cause problems. The front surface of the flange wings (not the rear, seating surface) can be lathed down if necessary.

There can also be potential issues with the chamfer around the lip of the camera mount and the right angle cut of the lens mount where the rear cylinder goes inside the camera mount. If there is too much of a rounded corner on the lens (or adapter) mount it may not seat properly. I’ve sometimes had to lathe an undercut on cheap PL mounts so they seat properly.

Unless it’s distorted a machinist should be able to fix the issue.

Thank you! It might be the chamfer. It's so close to fitting. I'll probably take it to machinist when I get back to LA.