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04-29-2012, 06:31 AM   #1
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Non-Pentax K bellows unit - lens won't stop down

Hi,

So I've got an old Panagor bellows unit (like this one) which came as part of an ebay auction bundle a while ago.

It's got an aperture lever on the camera-side mount which, when I move it, moves the aperture lever on the mounted (M) lens and opens the iris in the normal way.

When I mount the whole assembly on the camera in M mode, the iris remains fully open all the time - I can't close it by operating the shutter, the green button or DOF-preview.

Wide open is pretty useless for macro shots, obviously!

I have a workaround which I don't really want to try outdoors or on a tripod, which is to compose normally then release the bellows from the body and rotate it so the aperture lever is no longer actuated and the aperture set on the lens takes precedence - then I can use the green button to meter (like I would on an M42 lens) and shoot.

This bellows unit was essentially free so getting it working properly obviously isn't a big deal - but it'd be nice.

Any ideas?

04-29-2012, 06:48 AM   #2
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Hi, Tim
Info not much use for your unit, but the Pentax Auto Bellows M lever does not go back to the camera, it is actuated by a button/cable release on the front carriage.
The button is held down while the shutter is released
If you can dis-assemble and remove the lever, you can compose wide open then stop down the M lenses manually. Hope you get it working there.
04-29-2012, 07:25 AM   #3
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QuoteOriginally posted by wombat2go Quote
Hi, Tim
Info not much use for your unit, but the Pentax Auto Bellows M lever does not go back to the camera, it is actuated by a button/cable release on the front carriage.
The button is held down while the shutter is released
If you can dis-assemble and remove the lever, you can compose wide open then stop down the M lenses manually. Hope you get it working there.
Contax and Minolta Auto Bellows operate the same way as the Pentax Auto Bellow....

04-29-2012, 07:47 AM - 1 Like   #4
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QuoteOriginally posted by timh Quote
Hi,

So I've got an old Panagor bellows unit (like this one) which came as part of an ebay auction bundle a while ago.

It's got an aperture lever on the camera-side mount which, when I move it, moves the aperture lever on the mounted (M) lens and opens the iris in the normal way.

When I mount the whole assembly on the camera in M mode, the iris remains fully open all the time - I can't close it by operating the shutter, the green button or DOF-preview.

Wide open is pretty useless for macro shots, obviously!

I have a workaround which I don't really want to try outdoors or on a tripod, which is to compose normally then release the bellows from the body and rotate it so the aperture lever is no longer actuated and the aperture set on the lens takes precedence - then I can use the green button to meter (like I would on an M42 lens) and shoot.

This bellows unit was essentially free so getting it working properly obviously isn't a big deal - but it'd be nice.

Any ideas?
Two solutions come to mind:

1) The problem may be that the camera doesn't know a lens is mounted when the bellows is in place. To see if this is the case, short out all the camera mount electrical contacts with a piece of aluminum foil when mounting the bellows. If the green button now works, make sure the mount pins are touching bare metal when the bellows is mounted by removing finish, etc...

2) Counter-rotate the bellows so the lever is no longer activated then drill a new hole in the mount end of the bellows so the locking pin engages at that rotation. Then when you mount the bellows it'll stop and lock in the new location & allow the use of the lens' aperture ring.

I hope the first solution works. If so, you'll have a valuable bellows!

PS I'd like to see this bellows, unfortunately your link fails.

04-29-2012, 09:43 AM - 1 Like   #5
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QuoteOriginally posted by newarts Quote
1) The problem may be that the camera doesn't know a lens is mounted when the bellows is in place. To see if this is the case, short out all the camera mount electrical contacts with a piece of aluminum foil when mounting the bellows. If the green button now works, make sure the mount pins are touching bare metal when the bellows is mounted by removing finish, etc...
This definitely sounds like the issue, it sounds like the pins aren't being shorted by the bellows, thus the camera doesn't know anything is attached. Emphasis on "sounds like," as in most cases in life, I could very easily be wrong.
04-29-2012, 01:13 PM   #6
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Thanks for the responses!

QuoteOriginally posted by newarts Quote
1) The problem may be that the camera doesn't know a lens is mounted when the bellows is in place. To see if this is the case, short out all the camera mount electrical contacts with a piece of aluminum foil when mounting the bellows. If the green button now works, make sure the mount pins are touching bare metal when the bellows is mounted by removing finish, etc...
Aha! This is it. I managed to get it working with foil, then filed the coating off the rear of the bellows in the area where the electrical contacts connect - and that works too! Excellent.

I've now remembered vaguely reading something related to this before, but it was so long ago that the info moved to some remote and inaccessible part of my brain. Much appreciated!

Pics of bellows:









So, turns out it's actually a pretty good bit of kit!
04-29-2012, 01:21 PM   #7
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QuoteOriginally posted by timh Quote
Thanks for the responses!
....
I managed to get it working with foil, then filed the coating off the rear of the bellows in the area where the electrical contacts connect - and that works too! Excellent.

So, turns out it's actually a pretty good bit of kit!
I'll say! It is the only Pentax K bellows I've seen with an aperture lever. How is the front aperture lever connected to the rear lever?

I wonder if it was sold using other brand names?

A BIG thank you for reporting your success & including the photos! There is far too little outcome reporting in on-line forums!
04-29-2012, 01:42 PM   #8
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No problem - if someone else gets hold of one they are likely to search for an answer in the same way I did before posting.

The levers (and the stop-down coupler on the opposite side) are linked to those two silver rails with square profiles in such a way that when either is moved the rail rotates and the adjustment is mirrored on the opposite end. It's very simple and quite clever, really.

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