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02-11-2017, 10:17 AM   #1
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Keeping AdaptAll Lens Stopped Down

I have been investigating ways I could continue using my K-30 in case it does succumb to the "aperture block" malady.
Dark exposure problems on K-30 or K-50? Read me first! - PentaxForums.com

The problem occurs when the camera attempts to "stop down", but apparently the mechanism fails to stop the aperture at the correct point, so it closes to its smallest aperture. An obvious solution is to prevent the lens from needing to stop down, that is, to keep it stopped down all the time. I've seen several guys here say that they had clipped the aperture lever for that reason, but that solution leaves me cold, because I hate to cripple a perfectly good lens that has survived in that condition for twenty years or more. Then I thought of my AdaptAll lenses. I did find someone here who modified an M42-mount to keep the lens stopped down
An Adaptall to M42 adapter modification - PentaxForums.com

That is a good solution, but as I examined my AdaptAll lenses, I realized there is another solution. If you look at the back of an AdaptAll lens



you can see a small button/lever {encircled in red in the picture above}; the adapter which specializes the lens for a particular mount transfers pushes from the mount to this button; block this button, and the lens stays stopped down, so I cut a small strip from a piece of thin plastic {such as flashing holding the "reward cards" to the right}, put that piece over the lever, and used a small piece of tape to hold it in place as I put the adapter on. I wouldn't want to take the adapter off again, but I have done this with two lenses {#23A 60-300mm f3.8-5.4 and #01A 35-80mm f/2.8-3.8} and this does seem to keep the lens stopped down {I took the picture above with the #01A, incidentally}

02-11-2017, 10:46 AM   #2
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Yep that works. Also M42 lenses and early adaptalls with a M-A button/switch will give you full stop down control.
02-11-2017, 11:11 AM   #3
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When I used those lenses I picked up an adaptall-m42 adapter, and a k-m42 adapter on the body. The aperture would be adjusted with the ring. It worked around the fragile adaptall KA adapters.
11-25-2018, 11:57 AM   #4
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The photo in my original post got lost, so I am repeating the OP with the image re-inserted:


I have been investigating ways I could continue using my K-30 in case it does succumb to the "aperture block" malady.
Dark exposure problems on K-30 or K-50? Read me first! - PentaxForums.com

The problem occurs when the camera attempts to "stop down", but apparently the mechanism fails to stop the aperture at the correct point, so it closes to its smallest aperture. An obvious solution is to prevent the lens from needing to stop down, that is, to keep it stopped down all the time. I've seen several guys here say that they had clipped the aperture lever for that reason, but that solution leaves me cold, because I hate to cripple a perfectly good lens that has survived in that condition for twenty years or more. Then I thought of my AdaptAll lenses. I did find someone here who modified an M42-mount to keep the lens stopped down
An Adaptall to M42 adapter modification - PentaxForums.com

That is a good solution, but as I examined my AdaptAll lenses, I realized there is another solution. If you look at the back of an AdaptAll lens



you can see a small button/lever {encircled in red in the picture above}; the adapter which specializes the lens for a particular mount transfers pushes from the mount to this button; block this button, and the lens stays stopped down, so I cut a small strip from a piece of thin plastic {such as flashing holding the "reward cards" to the right}, put that piece over the lever, and used a small piece of tape to hold it in place as I put the adapter on. I wouldn't want to take the adapter off again, but I have done this with two lenses {#23A 60-300mm f3.8-5.4 and #01A 35-80mm f/2.8-3.8} and this does seem to keep the lens stopped down {I took the picture above with the #01A, incidentally}

11-25-2018, 03:16 PM - 1 Like   #5
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The piece of credit-card option does work, provided the piece of card doesn't come adrift and get lodged in the camera (experience speaking) ... a valid alternative is the aftermarket "K&F Concept" Tamron-PK adaptor which has no mechanical or electrical connections but activates the aperture mechanism in the lens by default.


I have a quantity of Tamron Adaptall-2 lenses which get a certain amount of use, but only 2 genuine Tamron PKA adaptors, which I don't like to swap about too much, so I have one of the K&F adaptors on my 500mm mirror lens 'cos that's got no aperture to control On any other Adaptall lens this adaptor "converts" the lens to a manual stop-down lens. Not quite as convenient as an A/M switch, but given the current asking prices for the genuine Tamron article, worth considering if you can live with manual aperture.


YMMV Good luck!
11-25-2018, 03:29 PM   #6
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Another option having the same effect is to get one of the 3rd-party Adaptall mounts. These provide full manual aperture action only and would function nicely for your task. The lens side of the Fotodiox version is pictured below:

Fotodiox | Tamron Adaptall (Adaptall-2) for Pentax K



Edit: Apologies to @kyper whose suggestion of the same thing, I did not notice.


Steve

(...no connection to Fotodiox...)

Last edited by stevebrot; 11-25-2018 at 03:35 PM.
11-25-2018, 05:39 PM   #7
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QuoteOriginally posted by kypfer Quote
The piece of credit-card option does work, provided the piece of card doesn't come adrift and get lodged in the camera (experience speaking) ... a valid alternative is the aftermarket "K&F Concept" Tamron-PK adaptor which has no mechanical or electrical connections but activates the aperture mechanism in the lens by default.

I have a quantity of Tamron Adaptall-2 lenses which get a certain amount of use, but only 2 genuine Tamron PKA adaptors, which I don't like to swap about too much, so I have one of the K&F adaptors on my 500mm mirror lens 'cos that's got no aperture to control On any other Adaptall lens this adaptor "converts" the lens to a manual stop-down lens. Not quite as convenient as an A/M switch, but given the current asking prices for the genuine Tamron article, worth considering if you can live with manual aperture.
QuoteOriginally posted by stevebrot Quote
Another option having the same effect is to get one of the 3rd-party Adaptall mounts. These provide full manual aperture action only and would function nicely for your task. The lens side of the Fotodiox version is pictured below:

Edit: Apologies to @kyper whose suggestion of the same thing, I did not notice.
(...no connection to Fotodiox...)
Thank you both of you - I guess I reinvented the wheel. All of my mounts for AdaptAll are by Tamron, so I wasn't aware that you could get the same place by being cheaper.

I originally started this thread almost two years ago as I thought about what to do once my K-30 ran into issues; I disinterred this thread because I noticed I had inadvertently deleted the photo. Fortunately, I didn't need anything like this until a couple weeks ago - and since my KP from B&H is on a truck in the middle of Ohio, I suppose I won't actually use this thing - but I hope your suggestions might be of use to someone else.
11-25-2018, 05:49 PM   #8
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QuoteOriginally posted by reh321 Quote
since my KP from B&H is on a truck in the middle of Ohio
Yay!

QuoteOriginally posted by reh321 Quote
I suppose I won't actually use this thing
Strangely, I may very well get one of those cheap adapters to allow fine control of shutter speed as an alternative to the PKA adapter that I own.


Steve

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