Modifying an M42 to K adapter

Beepaitch · 10-27-2019, 02:15 PM

Hi,
I have an M42 to K adapter with some inherited kit which I’d like to use with an old Pentacon lenses.
Removing these adapters is a pain (right?), so I’m wondering about semi-permanently attaching it to the lens.
Because these adapters lock in I’d have to remove the locking tab/spring thing.

Any thoughts? Bad idea? Cheers!

**boriscleto** · 10-27-2019, 02:26 PM

A genuine Asahi/Pentax adapter ring or third party?

Does the Pentacon have an A/M switch? If not you will need a third party adapter with an inner rim that pushes in the aperture pin, or modify the lens to keep the pin pushed in. If the Pentacon is a pre-set there is no problem...

wstruth · 10-27-2019, 02:28 PM

I wouldn't do it to the Pentax version since it's pretty well made. but I've done this with inexpensive third party ones. But when I remove the spring it just means the lens can be removed without depressing the tab spring.

**clickclick** · 10-27-2019, 02:38 PM - **1 Like**

The flush mounting adapters have the locking spring held on by a single screw. It's easy enough to just remove it and the spring. You don't need to do anything more than that. I leave a dedicated adapter without spring on many of my M42 lenses. I just tighten them by hand on to the lens and never have a problem with them coming off the lens, and I don't have problems with the lenses coming off the bodies, even though the locking spring is removed.

08amczb · 10-27-2019, 02:48 PM

The only negative thing I can see is your lens can turned and removed without pressing any button, so you can drop it accidentally.
I modified an M42-PK adapter too for my Helios.

stevebrot · 10-27-2019, 02:49 PM

Originally posted by Beepaitch

Removing these adapters is a pain (right?)

Not if if the adapter is genuine Pentax. With those, removal is easy. As for doing a permanent mounting with the spring removed, that is a common strategy on this site.

Steve

**jatrax** · 10-27-2019, 02:50 PM

Originally posted by Beepaitch

Removing these adapters is a pain (right?)

Depends. The OEM one is not hard to remove at all.

Originally posted by Beepaitch

Because these adapters lock in I’d have to remove the locking tab/spring thing.

I wouldn't do that to an official Pentax one. First, they are not hard to remove and second they are too valuable to modify. The third party adapters come in a range of quality with the poorest being pure junk and the best being almost but not quite as good as the Pentax one. If you want to leave an adapter on a lens just buy a good third party one and remove the locking tab and leave it on the lens.

I have several third party ones that stay permanently on several lenses but for most lenses I use an official Pentax one and unscrew the lens as needed. Basically all the smaller lenses get unscrewed and a couple of really big lenses have a permanent adapter as they are awkward to unscrew.

Beepaitch · 10-27-2019, 03:04 PM

Ok thanks all, seems the consensus is ‘don’t modify a genuine one’. I am completely new to Pentax so have no idea what’s worth a bit and what’s 10-a-penny.
I’ll have a good look at it tomorrow to see if it looks genuine, and whether the locking spring is held in my a spring. All I know for sure is my grandad bought it in early 90s when he got a P30T.
Cheers, sleep time over here!

Beepaitch · 10-27-2019, 03:18 PM

Ok decided to check now while you’re all on the subject. What do you reckon, genuine or repro?

**sergysergy** · 10-27-2019, 03:39 PM

not original

**clickclick** · 10-27-2019, 03:45 PM

Yep, not original. One of the signs is the original will have blackened surfaces that are internally facing for reducing reflections. I've had decent luck with generic adapters like what you have, and it's a prime candidate to remove the screw and spring and leave it on a lens. I also don't know what the taboo is on doing it to a genuine one. These ain't hen's teeth. You can find them on eBay for around $30-35 pretty typically. Just don't loose them and you can put it back if you want.

**UncleVanya** · 10-27-2019, 06:34 PM

I've seen people use adapters that are secured with the type of loctite that isn't permanent.

nanhi · 10-27-2019, 08:04 PM

I think he just wants the retaining spring lock to be removed for easy removal from the lens without having to use a tool or a screw driver to remove the Adapter from the Camera Body.
Just unscrew the tiny screw holding the spring to the Adapter Body.
In case you want a firm grip of the Adaptor on the lens just use some rubber glue on the threads. This way the Adaptor will not stay in the camera Body. And if required you can screw out the Adapter again from the Lens albeit with a little force or by using a softening liquid like WD-40.

beachboy2 · 10-27-2019, 08:37 PM

My original adapter doesn't have any paint whatsoever. Engraved Pentax. Finer engineering than the above. I would remove the spring and clip and bin them.

**pentaxus** · 10-27-2019, 09:13 PM

On some you can remove the spring and screw and put the screw back in to hold the adapter tighter against the threads.

10-27-2019, 02:15 PM	#1
Beepaitch Senior Member Join Date: Oct 2019 Location: Gloucestershire, UK Posts: 111	Modifying an M42 to K adapter Hi, I have an M42 to K adapter with some inherited kit which I’d like to use with an old Pentacon lenses. Removing these adapters is a pain (right?), so I’m wondering about semi-permanently attaching it to the lens. Because these adapters lock in I’d have to remove the locking tab/spring thing. Any thoughts? Bad idea? Cheers!

10-27-2019, 03:18 PM	#9
Beepaitch Senior Member Join Date: Oct 2019 Location: Gloucestershire, UK Posts: 111 Original Poster	Ok decided to check now while you’re all on the subject. What do you reckon, genuine or repro? Attached Images

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10-27-2019, 02:26 PM	#2
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	A genuine Asahi/Pentax adapter ring or third party? Does the Pentacon have an A/M switch? If not you will need a third party adapter with an inner rim that pushes in the aperture pin, or modify the lens to keep the pin pushed in. If the Pentacon is a pre-set there is no problem...

10-27-2019, 02:28 PM	#3
wstruth Veteran Member Join Date: Nov 2010 Location: at my kitchen table Photos: Gallery \| Albums Posts: 1,294	I wouldn't do it to the Pentax version since it's pretty well made. but I've done this with inexpensive third party ones. But when I remove the spring it just means the lens can be removed without depressing the tab spring.

10-27-2019, 02:38 PM - 1 Like	#4
clickclick Loyal Site Supporter Join Date: May 2016 Location: East Coast Posts: 2,903	The flush mounting adapters have the locking spring held on by a single screw. It's easy enough to just remove it and the spring. You don't need to do anything more than that. I leave a dedicated adapter without spring on many of my M42 lenses. I just tighten them by hand on to the lens and never have a problem with them coming off the lens, and I don't have problems with the lenses coming off the bodies, even though the locking spring is removed.

10-27-2019, 02:48 PM	#5
08amczb Veteran Member Join Date: Dec 2013 Posts: 796	The only negative thing I can see is your lens can turned and removed without pressing any button, so you can drop it accidentally. I modified an M42-PK adapter too for my Helios.

10-27-2019, 02:49 PM	#6
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Beepaitch Removing these adapters is a pain (right?) Not if if the adapter is genuine Pentax. With those, removal is easy. As for doing a permanent mounting with the spring removed, that is a common strategy on this site. Steve

10-27-2019, 02:50 PM	#7
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Originally posted by Beepaitch Removing these adapters is a pain (right?) Depends. The OEM one is not hard to remove at all. Originally posted by Beepaitch Because these adapters lock in I’d have to remove the locking tab/spring thing. I wouldn't do that to an official Pentax one. First, they are not hard to remove and second they are too valuable to modify. The third party adapters come in a range of quality with the poorest being pure junk and the best being almost but not quite as good as the Pentax one. If you want to leave an adapter on a lens just buy a good third party one and remove the locking tab and leave it on the lens. I have several third party ones that stay permanently on several lenses but for most lenses I use an official Pentax one and unscrew the lens as needed. Basically all the smaller lenses get unscrewed and a couple of really big lenses have a permanent adapter as they are awkward to unscrew.

10-27-2019, 03:04 PM	#8
Beepaitch Senior Member Join Date: Oct 2019 Location: Gloucestershire, UK Posts: 111 Original Poster	Ok thanks all, seems the consensus is ‘don’t modify a genuine one’. I am completely new to Pentax so have no idea what’s worth a bit and what’s 10-a-penny. I’ll have a good look at it tomorrow to see if it looks genuine, and whether the locking spring is held in my a spring. All I know for sure is my grandad bought it in early 90s when he got a P30T. Cheers, sleep time over here!

10-27-2019, 03:39 PM	#10
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,170	not original

10-27-2019, 03:45 PM	#11
clickclick Loyal Site Supporter Join Date: May 2016 Location: East Coast Posts: 2,903	Yep, not original. One of the signs is the original will have blackened surfaces that are internally facing for reducing reflections. I've had decent luck with generic adapters like what you have, and it's a prime candidate to remove the screw and spring and leave it on a lens. I also don't know what the taboo is on doing it to a genuine one. These ain't hen's teeth. You can find them on eBay for around $30-35 pretty typically. Just don't loose them and you can put it back if you want.

10-27-2019, 06:34 PM	#12
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,404	I've seen people use adapters that are secured with the type of loctite that isn't permanent.

10-27-2019, 08:04 PM	#13
nanhi Veteran Member Join Date: May 2009 Location: Bangalore, India Photos: Gallery \| Albums Posts: 469	I think he just wants the retaining spring lock to be removed for easy removal from the lens without having to use a tool or a screw driver to remove the Adapter from the Camera Body. Just unscrew the tiny screw holding the spring to the Adapter Body. In case you want a firm grip of the Adaptor on the lens just use some rubber glue on the threads. This way the Adaptor will not stay in the camera Body. And if required you can screw out the Adapter again from the Lens albeit with a little force or by using a softening liquid like WD-40.

10-27-2019, 08:37 PM	#14
beachboy2 Senior Member Join Date: Dec 2012 Location: Perth Western Australia Photos: Gallery Posts: 222	My original adapter doesn't have any paint whatsoever. Engraved Pentax. Finer engineering than the above. I would remove the spring and clip and bin them.

10-27-2019, 09:13 PM	#15
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	On some you can remove the spring and screw and put the screw back in to hold the adapter tighter against the threads.