[ron6771]

Today I received a Pentacon 6 to Pentax 645 adapter. I bayoneted it into my Pentax 645Z camera body. When I press the lens release button and twist counter clockwise to remove the adapter, it will not move. I pressed the release button as deep as it goes, and gave a fair amount of force to the adapter, to no avail. Any suggestions on what can be done? This is upsetting.

[TDvN57]

Today I received a Pentacon 6 to Pentax 645 adapter. I bayoneted it into my Pentax 645Z camera body. When I press the lens release button and twist counter clockwise to remove the adapter, it will not move. I pressed the release button as deep as it goes, and gave a fair amount of force to the adapter, to no avail. Any suggestions on what can be done? This is upsetting.

This can be a major setback. I always test adapters new to me on some other adapter like a teleconverter or extension ring. Anyhow you are in the deep now and need to find a way out, not hear some smarts about woulda-coulda-shoulda.

It sounds as if the locking pin from the camera is pinched and cannot release. On the K mount the locking pin is on the front face of the flange, on the 645 and 6x7 the locking pin is hidden within the flange adge (female side). Most likely on a spring release. Meaning you press the release button, which pulls on a spring mechanism that pulls on the locking pin.

Being hidden within the female side of the flange makes it almost impossible to reach from the adapter side and your only obvious option would be to wiggle the adapter while holding the release button in all the time.

On the k mount the locking pin is a pin locking into a tiny hole on the lens. The 645 and 6x7 appears to be rather a stop behind one of the flange edges to prevent the lens/adapter from rotating counter clockwise. That would indicate that the adapter's flange edge protrusion is a fraction too 'wide' or long. Just enough to engage the lock mechanism but too tight to release it.

So incorporate as part of the wiggling, rotating the adapter clockwise hoping you can makeup the out-of-tolerance dimension with gentle wiggling.

Make sure you keep the release button pressed in while you do this, just in case the flange edge causing the problem is not wedging the lock more. So keeping the button pressed will cause the lock to release as soon as the adapter's flange retreats a bit.

More than this I can't help, and if this fails I suggest to get it to a technician that can pull more tricks or dismantle the adapter without damage to the camera.

Best of luck, and sorry to hear this issue had trapped you.

[UncleVanya]

@professerbuzz I saw in another thread that you had a 6x7 to 645 adapter get stuck and the only way to get it off was to disassemble the adapter. Can you elaborate here?

[Adam007]

I have an M42 adapter for a Pentacon lens for my K-1. I had the exact same issue you describe, but the solution is rather simple. On the adapter, there is a little "release". You need to push that in with your fingernail to release the lens. Seems ridiculous to me, but there you go. Do you have this type of adapter?

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[ProfessorBuzz]

Today I received a Pentacon 6 to Pentax 645 adapter. I bayoneted it into my Pentax 645Z camera body. When I press the lens release button and twist counter clockwise to remove the adapter, it will not move. I pressed the release button as deep as it goes, and gave a fair amount of force to the adapter, to no avail. Any suggestions on what can be done? This is upsetting.

What exact make and model of adapter is it? Contact the manufacturer right away - they will probably have removal instructions.

I had a couple of problem adapters that the tolerances were bad on the camera-side so they would stick, and two where the lens-release mechanisms would not release the lens.
Some of the adapters are made as a series of rings that bolt on top of each other with tiny screws. So if you can remove the lens, you may be able to remove the topmost rings to get to the bottom piece which is the bayonet to 645.
Temperature changes can sometimes help. eg get the adapter cooler. e.g. cover the lens hole. Take it outside, put the camera in a bag, and let it sit for an hour. Try to remove the bayonet again.
Let it warm up gradually so condensation does not form (or keep it in the bag).

[rdenney]

The P6 breech lock ring is threaded onto the adapter. If it is not tight onto a P6 lens (or all the way in the “tight” direction with no lens), it will tighten down onto the camera and prevent movement. Try turning the breech lock ring—remove the P6 lens from the adapter first—in both directions to make sure it isn’t tightened against the Pentax body. That seems to me the most likely issue if you are playing the the loose adapter with no P6 lens attached.

I doubt it’s the lock pin preventing removal. These sometimes bind in the bayonet, and only gentle but persistent fiddling works them loose. The adapter would be a bit less fiddly if the P6 had one more millimeter of lens flange mounting distance relative to the Pentax.

I find it much easier to remove if a P6 lens is well attached, but you have to figure it out first—hence the above things to try.

There is nothing to take apart on these adapters that will help, though you can remove the breech lock ring after removing the screw in the edge that serves as a limit pin.

Rick “just studied one to recall details” Denney