HELP - Cooke Kinetal Stuck in TS Adapter

[Willem Jansen]

I recently got a Cooke Kinetal 17.5mm lens and already had an Arri Standard TS adapter that came with an ACL kit I bought a few years ago. I never had a chance to actually use the adapter until now. The lens does fit the adapter, but I’m having quite a bit of trouble with the mounting/unmounting process. Getting the lens back out is almost impossible unless I loosen the small screws connected to the 3 retaining pins/tabs that hold the lens in place.

I’ve already spoken to Gregg McPherson about this and he’s been very helpful, but I figured I’d ask here as well in case someone has run into the same issue before or knows exactly what usually causes/fixes this.

At the moment I’ve removed the lens, carefully disassembled the adapter a bit, and taken some photos of the mechanism which I’ll attach below. One thing I completely overlooked at first was the locking ring and the fact that it affects the operation of the 3 retaining tabs. The ring itself also feels pretty stiff, including when I tried removing it.

My current guess is that the adapter probably has old dried grease and possibly not enough proper lubrication left for the mechanism to function smoothly anymore, but I’d really appreciate any thoughts from people more experienced with these adapters.

[Gregg MacPherson]

Is the grease really old? Does the lock ring for the tabs have full range of movement on the threads? Are the little springs correctly assembled?

Are you near any film camera or lens techs? They may spot the problem easily. If you have to do it yourself you can check the things above. Clean off all the grease and observe the movement on the threads, and the movement of the tabs, especially in the extreme open (tabs retracted) position.

[Willem Jansen]

The little springs are mounted under the screws and bend inward against the adapter, so they apply pressure against the tabs and push them slightly inward. I’m rather sure this was already how they were positioned before I disassembled anything.

The lock ring does have full range of movement on the threads, but it feels fairly stiff and not particularly smooth. The tabs themselves don’t really retract on their own unless I physically push them inward. Tightening the little spring screws also makes the movement noticeably stiffer very quickly.

From what I can tell so far, nothing appears broken or bent, so I’m starting to suspect old dried grease and friction in the threads/mechanism may be the main issue.

I’m doubtful whether there’s a tech close to me who even knows the slightest of what the adapter actually is supposed to be, let alone being able to fix it.

[Gregg MacPherson]

A technician, even without being familiar with the adapter, will immediately see how it is supposed to work, and whether the tabs are functioning properly.

I did open one of these adapters some years ago, but didn't remove the springs, and can't remember their shape.

Firstly, lets assume that all the old grease is removed and parts cleaned with solvent. With the lock ring in the release position, or fully removed, the springs should pull the tabs away from the lens axis, away from the lens mount. So the tabs should not be protruding into the lens port at all. If they are then the spring function is not correct.

So are the springs correctly mounted? Have they been bent? 

Where are you located? You may be surprised at how friendly, curious and helpful the technicians can be.

[Willem Jansen]

Quick update: I managed to get the adapter working properly again and can now mount and remove the Cooke Kinetal normally without it getting stuck.

The main issue turned out to be the little springs. They were installed incorrectly and bent inward, but they actually needed to be mounted outward so they apply pressure correctly to the tabs. Once I corrected that, the locking ring started functioning as intended again.

I also cleaned the threads and mechanism a bit, which improved the smoothness noticeably.