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02-20-2013, 09:23 AM   #1
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m42 adapter mods

I only have one m42 lens- tak 50 1.4 which I love using, especially now that I have a k-01 it is being used more due to the focus peaking feature. However, taking it off and on is still a pain because of the adapter and takes so long it makes me paranoid about dust. I was thinking of ways I could semi-permanently attach the adapter so that I could just attach it like a normal lens. Maybe some blue threadlocker? Before I do, however, has anyone been down this road before? Any pitfalls to be aware of?

02-20-2013, 09:29 AM   #2
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Hi. If you have an original adapter, best would be to sell it and get a cheap Chinese one from ebay (around $7 shipped) and remove the spring. It is held by a small screw and it is what is causing the adapter to stay on the body. My advice is don't mod the original adapter, because it is out of production and some people might like it that way. Instead, get a non-original one, which should work the same if the spring is removed. If you already have a non-original adapter, then just remove the spring.
02-20-2013, 09:31 AM   #3
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Was facing with the same issue...I just bought more M42 lenses ...the tak.50mm F/1.4 was the first one, then Vivitar 135, then Tak 28mm, then Tak solved the issue with the changeover time...
02-20-2013, 10:08 AM   #4
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DON'T USE BLUE THREADLOCK! It would be permanent.

There are two better options:

1) Use the Pentax made adapter. It is very easy to remove. You will always have the two step lens removal, unscrewing the lens, then removing the adapter from the camera as designed. It is very easy to remove. An easy touch from the corner of your finger nail is all that is required.

2) Permanently attach a cheap adapter with PURPLE THREADLOCK. It requires only four foot pounds of torque to remove. No damage results from a possible future removal. Remove the spring from the adapter. Put a small hole or groove in the base of the lens where the camera lock pin touches the lens. Additionally signal spots could be put on the base of the lens to let the camera know the widest aperture the camera is capable of, giving you more metering and mode possibilities. The lens base must be wide enough to add the signal spots if wanted. Also a flangeless adapter must be used.

I've a adapted three lenses by option two, a 300/4 Tak, 200/4 Tak, and a 35/2 Tak (67mm). On the 300 I added signal spots. The attachment of the adapter and making the lock pin retaining hole required an hour. Adding the signal spots required two more hours.

I did not adapt my 85/1.8 Tak or my 100/4 Tak macro. They are too valuable for me to touch. Those two and my lenses that have too narrow of a base, I use the first option.

There are multiple tutorials with pics on the web. I'll make one if you cannot one.

p.s. I bought a $5 used broken K mount camera for testing and measuring for permanent attachment.

Last edited by lmd91343; 02-20-2013 at 10:58 AM. Reason: Grammar fix
02-20-2013, 10:09 AM   #5
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Agree with kcobain1992 re the original adapter, it is too valuable at this point to mess with.
Get a cheap one (well not the cheapest, get a GOOD cheap one) and take out the spring. Search the forum and you will find several threads on this. The downside is that the adapter will no longer 'click' into place and CAN turn loose. This really does not happen in normal use, just so you understand that there is nothing but the adapter/camera mount friction holding it in place anymore.

I have permanently attached adapters on my S-M-C 300mm and S-M-C 400mm. For the rest I use the original adapter and just switch off. On the long lenses it is really a pain to thread them on which is why I went to the attached adapters.

Personally with only one M42, I would just use the adapter you have and not worry about it. It does not take that long to switch and I doubt the increased dust exposure is significant.
02-20-2013, 10:16 AM   #6
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QuoteOriginally posted by jatrax Quote
On the long lenses it is really a pain to thread them on
Agreed. If the adapter is not yet on the camera, I found it easier to screw it on the lens first, and then mount the lens on the body like a regular K-mount.
02-20-2013, 10:27 AM   #7
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Yes, you can semi-permanently attach an adapter to the lens with 'weak' thread lock (or a dab of rubber cement for that matter).

Keep in mind the following:

- ANY adapter, or method of mounting an adapter, that doesn't add space between the lens base and body will focus normally. Conversely, ANY method that DOES add space acts as an extension ring.

- The original idea for the adapter was that it be fixed in place on the body so pros with large investments in M42 lenses would be able to gradually upgrade to a new set of PK lenses for the PK bodies. The fact that it's inconvenient to remove the adapter was a design feature, not a fault.

- So long as the lens base is flush with the body (to maintain the registration distance) an adapter can be "glued" to the lens at any depth and rotational position. Take advantage of that to adjust your screw mount lenses so the aperture index isn't hidden by the flash bulge - it's much more convenient to use 'em that way.

I've modified some 'top hat' adapters, those that prevent infinity focus, by reducing the flange so its diameter is no greater than the bayonet lugs (like an OEM adapter) and temporarily gluing them to the lens. This essentially results in a K- or M-class lens with no focus issues. In most cases, the base of these lenses isn't wide enough to short out the data pins.

Also see:

02-20-2013, 11:57 PM   #8
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Another reason not to modify the geniune Pentax adapter is that it's designed to be a loose fit in the camera body, the action of screwing on a lens tightening everything up - and that's why it's easy to remove. Using this adapter, your modified lens might then likewise end up being a somewhat loose fit. Most of the cheap adapters (particularly those which come with removal tools) are a fairly tight fit and would be a much more suitable basis for changing your screwmount to PK.

02-23-2013, 02:05 PM   #9
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Original Poster
Thanks for all the words of advice, especially about not using the blue threadlock! I'm going to do some more searching( my original search didn't turn up anything) and some experimenting. I think I have a Pentax-made adapter, it works very well and isn't end-of-the-world hard to remove, but if I can get it so that I can skip that step it would be much nicer. I'll leave that one alone, as suggested and get a couple cheap adapters. Oh, I also found a tak 135 m42 that I forgot about.

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