Original Asahi Pentax adapter stuck in K-S2

reh321 · 06-20-2016, 07:24 AM

Originally posted by pathdoc

There have been people who have (carefully) drilled a hole in the adapter to take the retaining plunger in the K mount, then put it on the lens with loctite. This basically gives them a stop-down K mount lens. I wouldn't try that without meticulous, precise marking of the adapter followed by the very careful use of a vise and drill press. Definitely one to try with a Chinese cheapie.

Part of the current reason for my having an M42 kit is backup in case my K-30 develops the aperture control problem, so another stop-down K-mount lens is the last thing I'd want to create.

pathdoc · 06-20-2016, 07:51 AM

Originally posted by reh321

so another stop-down K-mount lens is the last thing I'd want to create.

Except that with a modified M42 lens, the aperture control module comprises your brain and fingers.

reh321 · 06-20-2016, 09:04 AM

Originally posted by pathdoc

Except that with a modified M42 lens, the aperture control module comprises your brain and fingers.

I guess I don't understand what you mean.
All of my M42 lenses have a manual mode, so when I use them with the genuine Chinese adapter, they are always in the f-stop set on the aperture dial.
How would your modification change that?

pathdoc · 06-20-2016, 09:15 AM

Originally posted by reh321

How would your modification change that?

The mod I'm describing is the drilling of a shallow hole or indent in the lens, so that when a K-mount adapter without the clip is put on it, it locks into place on the camera the same way a K, M, A etc. lens does and can be taken off in the same way, as easily as any K. In effect, it becomes a K-mount lens with Takumar stop-down features.

**boriscleto** · 06-20-2016, 09:50 AM

Originally posted by pathdoc

Yes, it does. That's the point of removing the retaining spring.

There have been people who have (carefully) drilled a hole in the adapter to take the retaining plunger in the K mount, then put it on the lens with loctite. This basically gives them a stop-down K mount lens. I wouldn't try that without meticulous, precise marking of the adapter followed by the very careful use of a vise and drill press. Definitely one to try with a Chinese cheapie.

You don't drill a hole in the adapter. The adapter sits entirely inside the mount. You drill a hole in the back of the lens, if the lens has a wide enough base...

pathdoc · 06-20-2016, 10:22 AM

Originally posted by boriscleto

You don't drill a hole in the adapter. The adapter sits entirely inside the mount.

LOL yeah, I know; I have already acknowledged my silly mistake above. My bad.

**GUB** · 06-20-2016, 04:02 PM

Originally posted by pathdoc

K-mount lens with Takumar stop-down features

A better way to say this is it becomes a fully manual K mount lens. I achieve the same with M series lens by drilling another locating hole in the lens base about 7mm before the locating slot. When the M lens locks in there it hasn't quite fully mounted and then performs as a fully manual lens. I always have had indifferent results with the green button and this mod means it works effectively in AV.

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06-20-2016, 07:24 AM	#46
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,185	Originally posted by pathdoc There have been people who have (carefully) drilled a hole in the adapter to take the retaining plunger in the K mount, then put it on the lens with loctite. This basically gives them a stop-down K mount lens. I wouldn't try that without meticulous, precise marking of the adapter followed by the very careful use of a vise and drill press. Definitely one to try with a Chinese cheapie. Part of the current reason for my having an M42 kit is backup in case my K-30 develops the aperture control problem, so another stop-down K-mount lens is the last thing I'd want to create.

06-20-2016, 07:51 AM	#47
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by reh321 so another stop-down K-mount lens is the last thing I'd want to create. Except that with a modified M42 lens, the aperture control module comprises your brain and fingers.

06-20-2016, 09:04 AM	#48
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,185	Originally posted by pathdoc Except that with a modified M42 lens, the aperture control module comprises your brain and fingers. I guess I don't understand what you mean. All of my M42 lenses have a manual mode, so when I use them with the genuine Chinese adapter, they are always in the f-stop set on the aperture dial. How would your modification change that?

06-20-2016, 09:15 AM	#49
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by reh321 How would your modification change that? The mod I'm describing is the drilling of a shallow hole or indent in the lens, so that when a K-mount adapter without the clip is put on it, it locks into place on the camera the same way a K, M, A etc. lens does and can be taken off in the same way, as easily as any K. In effect, it becomes a K-mount lens with Takumar stop-down features.

06-20-2016, 09:50 AM	#50
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,477	Originally posted by pathdoc Yes, it does. That's the point of removing the retaining spring. There have been people who have (carefully) drilled a hole in the adapter to take the retaining plunger in the K mount, then put it on the lens with loctite. This basically gives them a stop-down K mount lens. I wouldn't try that without meticulous, precise marking of the adapter followed by the very careful use of a vise and drill press. Definitely one to try with a Chinese cheapie. You don't drill a hole in the adapter. The adapter sits entirely inside the mount. You drill a hole in the back of the lens, if the lens has a wide enough base...

06-20-2016, 10:22 AM	#51
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by boriscleto You don't drill a hole in the adapter. The adapter sits entirely inside the mount. LOL yeah, I know; I have already acknowledged my silly mistake above. My bad.

06-20-2016, 04:02 PM	#52
GUB Loyal Site Supporter Join Date: Aug 2012 Location: Wanganui Photos: Gallery \| Albums Posts: 5,760	Originally posted by pathdoc K-mount lens with Takumar stop-down features A better way to say this is it becomes a fully manual K mount lens. I achieve the same with M series lens by drilling another locating hole in the lens base about 7mm before the locating slot. When the M lens locks in there it hasn't quite fully mounted and then performs as a fully manual lens. I always have had indifferent results with the green button and this mod means it works effectively in AV.