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08-30-2009, 09:31 PM   #1
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Super Tak 55mm k mount conversion help needed

I recently invested in a 55mm f1.8 Super Takumar and I have fallen in love with it. I have a mount adapter on it but there is no way to lock the lens on the body. The base of the lens is too small to notch. I would like a solution that allows locking just like a normal K mount lens. Does anybody have any ideas?

08-31-2009, 02:31 AM   #2
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There have been a number of threads concerning the semi permanent modification of M42 lenses to K mount. Some of these threads are:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/68480-infinity...42-lenses.html
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/54595-flanged-...xperiment.html
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/69734-found-go...t-adapter.html
There has not been single practical solution that workes for all lenses yet though.
08-31-2009, 02:46 AM   #3
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QuoteQuote:
I recently invested in a 55mm f1.8 Super Takumar and I have fallen in love with it. I have a mount adapter on it but there is no way to lock the lens on the body. The base of the lens is too small to notch. I would like a solution that allows locking just like a normal K mount lens. Does anybody have any ideas?
there isn't a way to make an m42 lens mount just like a K mount. why not just purchase the K mount version? the optical formula is the same as the SMC Takumar 1.8\55

Pentax Lens Review Database - 55mm F1.8

I own a whole slew of Takumar 55's as well as the K mount version. it is just as good as all the others. its larger and heavier being K mount. it has a 52mm filter ring as opposed to 49 of most Takumars; but where it counts, you will be just as impressed. the K mount version is a little less common than the m42 versions but if you really want to use a 1.8/55, this really is the way to go. trying to modify a lens from another mount is really not.

QuoteQuote:
There has not been single practical solution that workes for all lenses yet though.
and there never will be.

Last edited by séamuis; 08-31-2009 at 02:53 AM.
08-31-2009, 07:36 AM   #4
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QuoteOriginally posted by séamuis Quote
... why not just purchase the K mount version? the optical formula is the same as the SMC Takumar 1.8\55 ...
I didn't want to go with the k mount variety because I use it a lot of the time in av mode.

08-31-2009, 08:11 AM   #5
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QuoteOriginally posted by Steve Beswick Quote
I didn't want to go with the k mount variety because I use it a lot of the time in av mode.
then honestly I don't know what to tell you. there is no way to modify any Takumar 1.8/55 to mount and un-mount like a Kmount lens without loosing infinity focus, unless you do some serious surgery to the mount. which may not be possible either and really not worth the trouble and possibility of completely destroying the lens.

maybe you should look into a lens with a similar focal length and max aperture from another brand in m42 mount? you may find one that has a base large enough to 'notch'. it wont be a Takumar, though you know that. the simple fact is, that its an m42 lens and you are trying to use it on a body designed for use with AF K mount lenses. just about all Takumars are too small to 'notch' (in my opinion, that's a good thing). you can either deal with the limitations or not use the lens. I wish I could help you, but I just don't believe there is a way to achieve what you want.

Last edited by séamuis; 08-31-2009 at 08:17 AM.
08-31-2009, 08:21 AM   #6
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QuoteOriginally posted by Steve Beswick Quote
I didn't want to go with the k mount variety because I use it a lot of the time in av mode.
Then all you have to do is remove the Aperture lever from a K-mount version. Then you'll have a full time AV (or Manual) lens

It's what I've done, so I could use it on my system, and it works Great.
08-31-2009, 08:24 AM   #7
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QuoteOriginally posted by little laker Quote
Then all you have to do is remove the Aperture lever from a K-mount version. Then you'll have a full time AV (or Manual) lens

It's what I've done, so I could use it on my system, and it works Great.

never thought of modifying the K mount. is it reversible? can you show us some photos of the modified lens?
08-31-2009, 07:21 PM   #8
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I have an idea I'm working on. I need some info first before I go any further though. Does anybody know how thick the metal at the base of the lens is?

08-31-2009, 08:12 PM   #9
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The only solution to do it would be to use Locktite thread lock, the red to hold a non flanged k-mount adapter on the lens. It would be semi-permanent and you better be sure to not get on the pins etc. That way, you won't have issues with infinity focus and the red will hold some serious torque.
08-31-2009, 08:44 PM   #10
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I just happen to be workin' on (solving?) this issue at pressent.

In general, what I plan to do is mark the SIDE of the base of the lens at the proper point near the camera latch pin and spot drill, thread and insert a 'pin' in the side of the barrel of those M42 lenses that are too small in diameter to spot drill the base of the lens. The pin would then catch on the body latch and prevent the lens from rotating unless the lens release latch was depressed. An M42 to bayonet adapter would still be required of course.

If anyone has already tried this without success I'd like to hear your thoughts.

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08-31-2009, 08:56 PM   #11
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As noted above, you have two options if you must have a 55/1.8 to use in Av mode that is a permanent K-mount:
Modify a M42 Takumar by permanently mounting a non-flanged adapter (spring removed) and notching the lens to engage the pin on the camera body
-or-
Modify a Pentax-K 55/1.8 to make it manual aperture only
For practical reasons, the former solution is the most attractive:
  • The Pentax-K 55/1.8 is becoming increasingly hard to find and the price (usually $50+) reflects this
  • The M42 Takumars are relatively common and cheap
  • Notching the base of the Takumar may affect future value, but does not affect the lens functionality

Steve
08-31-2009, 09:00 PM   #12
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QuoteOriginally posted by pacerr Quote
I just happen to be workin' on (solving?) this issue at pressent.

In general, what I plan to do is mark the SIDE of the base of the lens at the proper point near the camera latch pin and spot drill, thread and insert a 'pin' in the side of the barrel of those M42 lenses that are too small in diameter to spot drill the base of the lens. The pin would then catch on the body latch and prevent the lens from rotating unless the lens release latch was depressed. An M42 to bayonet adapter would still be required of course.

If anyone has already tried this without success I'd like to hear your thoughts.

H2
Several users have proposed mounting (glue/screw) an extension of some sort to the side of the lens, though I am not sure how successful those efforts have been. An ideal solution would be some sort of collar to mount on a narrow-based lens that would engage the K-mount lens release latch.

Steve
09-01-2009, 05:23 AM   #13
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a while ago I posted a question about adjusting the infinity focus of lenses to account for the flanged based adaptor.

The response back from forum members was that it probably can't be done in many cases. the only other option would be to try and remove the 0.8mm of the flanged adaptor from the lens base, but I am not sure how easy that would be

as a result, the OP somewhat stuck (no pun intended) with having no perminent mount on his M42's. BUT, how about making a body an M42 body.

Used bodies are becoming relitively cheap as newer models come out. why not just commit a body to be an M42 body.
09-01-2009, 05:30 AM   #14
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QuoteOriginally posted by Lowell Goudge Quote
as a result, the OP somewhat stuck (no pun intended) with having no perminent mount on his M42's. BUT, how about making a body an M42 body.

Used bodies are becoming relitively cheap as newer models come out. why not just commit a body to be an M42 body.
this is of course the easiest and in the long run, very likely the most economical. I have done this very thing myself by recently purchasing a *istD and putting a split-image focusing screen in it. a Pentax adapter on the mount and its my dedicated digital m42 body.

instead of coming up with ways to modify the lenses (which is rather dumb in my opinion) we should be focusing on a way to convert a K mount body into an m42 body. some sort of permanent mount swap.
09-01-2009, 06:08 AM   #15
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I wonder how difficult it would be to modify a body to operate the aperture pin on the M42 lenses? The actuator is there anyway to operate the K mount aperture lever so all it would need is some additional mechanism. Another project to add to the list...
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