Pentax Super Takumar 50mm 1.4 does not focus to infinity

alter ego 6x9 · Jul 14, 2014

I have it mounted on Spotmatic F. The "infinity" on the lens is at about 10 meters when looking through the viewfinder. I have other M42 lenses mounted on the same camera and they focus to infinity or even slightly past it, but this Super Takumar does not reach the infinity. I was mainly shooting at shorter distances (portrait) in the past with this lens, so I did not notice this issue. And at short distances the focus (on negatives) was accurate, but yesterday I tried to take some landscape pictures and noticed this issue. I did not develop the film yet, so not sure how this will look on the negative, nevertheless - what could be an issue?

Xmas · Jul 14, 2014

You have forced the lens past the stop is the most likely. If the symptoms get worse then Id recommend a service.

Won't make any difference to photos normally.

Kirks518 · Jul 14, 2014

My guess; The lens was taken apart in the past, and the focus helicoil wasn't put back on properly.

John Koehrer · Jul 14, 2014

Or, the most common is loose set screws in the focusing ring.
To fix it, set focus to infinity, loosen the screws a bit and set the ring so it lines up. Tighten the screws.

oreston · Jul 15, 2014

John Koehrer said:
Or, the most common is loose set screws in the focusing ring.
To fix it, set focus to infinity, loosen the screws a bit and set the ring so it lines up. Tighten the screws.

This is a great advice and might hopefully solve the problem. Those set screws loosening over the decades and slipping is certainly the likeliest explanation, however I do have a cautionary tale.

I once sorted out (so I thought) a couple of Takumars in this way. They were focussing slightly past infinity on a Spotmatic SP II. Took me an embarrassingly long while to realise that it was in fact the camera body, and not the lenses, that was out of whack

If possible, before doing anything else it would be useful to check the lens on another camera body. If the lens exhibits the same focussing scale error on another camera, you'll know for definite where the error lies.

alter ego 6x9 · Jul 15, 2014

oreston said:
This is a great advice and might hopefully solve the problem. Those set screws loosening over the decades and slipping is certainly the likeliest explanation, however I do have a cautionary tale.

I once sorted out (so I thought) a couple of Takumars in this way. They were focussing slightly past infinity on a Spotmatic SP II. Took me an embarrassingly long while to realise that it was in fact the camera body, and not the lenses, that was out of whack

If possible, before doing anything else it would be useful to check the lens on another camera body. If the lens exhibits the same focussing scale error on another camera, you'll know for definite where the error lies.

Great advice, I will start with this...

jochen · Jul 16, 2014

Hello,
you find several very useful links in the net how to open and repair this lens with many pictures and even movies. The infinity lock is not made by the set screws in the outside focussing ring but there are fixing screws who stop the rotation of the complete lens barrel in the helicoil. If this doesn't work, the lens barrel has been put back into a wrong entrance of the multi-thread helicoil by somebody who did'nt know what he does. At first you have to check the correct infinity focus in the film plane and then you fix the screws slightly loosened before. You get into the lens after removing the front inscription ring in the filter thread with a rubber tool. This is a great lens and worth fixing it.

oreston · Jul 16, 2014

jochen said:
Hello,
you find several very useful links in the net how to open and repair this lens with many pictures and even movies. The infinity lock is not made by the set screws in the outside focussing ring but there are fixing screws who stop the rotation of the complete lens barrel in the helicoil. If this doesn't work, the lens barrel has been put back into a wrong entrance of the multi-thread helicoil by somebody who did'nt know what he does. At first you have to check the correct infinity focus in the film plane and then you fix the screws slightly loosened before. You get into the lens after removing the front inscription ring in the filter thread with a rubber tool. This is a great lens and worth fixing it.

These screws are actually the ones I had in mind! (Reading back, and as Jochen points out, I realise that the earlier poster was talking about the tiny screws on the outside of the barrel). The front name ring will unscrew anti-clockwise. An improvised tool like an M42 rear lens cap with some duct tape or something similar around the edge is usually all you need to get it turning. Then there are just three screws to remove the part with the filter thread and you're in. The screws that secure the lens tube to the helical can then be slackened off and you can make the necessary adjustments as above.

alter ego 6x9 · Jul 16, 2014

Thanks everybody for advising me. I checked the lens on another camera and it has the same issue, so most likely you were correct with the diagnosis...

Kirks518 · Jul 16, 2014

I guess I'm confused.

a) Will the lens focus to infinity, ie, you can take a picture of something at infinity, and it will be in focus, but the barrel markings show it to not be at infinity?

Or

b) When you turn the focus ring to the infinity mark, the actual point of focus is about 10 meters away?

When I responded, I read the issue as b.

Also, i found a great 'tool' for removing the beauty ring, and other similarly secured parts on lenses - http://www.homedepot.com/p/Oatey-3-in-Plastic-Mechanical-Test-Plug-33402/100168770
It has a nice big hole in the middle that's tapered, so nothing touches the actual glass, and it's cheap. It comes in a couple of sizes, can't remember which size I have (2-1/2"?).

alter ego 6x9 · Jul 16, 2014

Kirks518 said:
I guess I'm confused.

a) Will the lens focus to infinity, ie, you can take a picture of something at infinity, and it will be in focus, but the barrel markings show it to not be at infinity?

Or

b) When you turn the focus ring to the infinity mark, the actual point of focus is about 10 meters away?

When I responded, I read the issue as b.

Also, i found a great 'tool' for removing the beauty ring, and other similarly secured parts on lenses - http://www.homedepot.com/p/Oatey-3-in-Plastic-Mechanical-Test-Plug-33402/100168770
It has a nice big hole in the middle that's tapered, so nothing touches the actual glass, and it's cheap. It comes in a couple of sizes, can't remember which size I have (2-1/2"?).

It is b) case.

Kirks518 · Jul 16, 2014

Then I stand by my original guesses - either the helicoid (?) was put back on wrong after a disassembly, or there is something out of whack.

David Lyga · Jul 16, 2014

VERY easy solution here: First, modify your 'alter ego' and get a set of miniature screwdrivers. Now, listen:

First, you need to unscrew the logo ring on the front of the lens. I usually pad each 180 degree side with several small layers of duct tape, then gently hold each arm of a scissors on each side and turn the scissors (counter clockwise). That usually starts the logo ring turning. When loose, you might even be able to unscrew it completely with your fingers. Of course, what I said assumed that the filter ring is not bent (Ouch! That would involve using pliers to straighten that filter ring and that is not too pleasant to do it correctly.) Also, make certain that the threads are CLEAN first, or you will be grinding dirt and causing much friction. I assume that that logo ring is now off the lens.

Then, unscrew the three screws holding that filter ring. Be careful not to lose anything in your exitement, alter-ego, or you will have to change your ego to one of angst.

Now, the fun part: you have three MORE screws to loosen: those holding the helical to the focusing ring. Simply LOOSEN (not remove) them and you can adjust infinity focus easily. Be at a convenient 'infinity' venue where you can check this out (i use my window which faces skyscrapers about 1/4 mile away), and when you are convinced that you are at (or, better, very slighly BEYOND, infinity), lock those three helical screws again and put back the filter ring and logo ring. And then you are done with the fun.

If you were in Philadelphia I would do this in five minutes for you. If you cannot follow this call me at 215.569.4949. - David Lyga

alter ego 6x9 · Jul 16, 2014

David Lyga said:
VERY easy solution here: First, modify your 'alter ego' and get a set of miniature screwdrivers. Now, listen:

First, you need to unscrew the logo ring on the front of the lens. I usually pad each 180 degree side with several small layers of duct tape, then gently hold each arm of a scissors on each side and turn the scissors (counter clockwise). That usually starts the logo ring turning. When loose, you might even be able to unscrew it completely with your fingers. Of course, what I said assumed that the filter ring is not bent (Ouch! That would involve using pliers to straighten that filter ring and that is not too pleasant to do it correctly.) Also, make certain that the threads are CLEAN first, or you will be grinding dirt and causing much friction. I assume that that logo ring is now off the lens.

Then, unscrew the three screws holding that filter ring. Be careful not to lose anything in your exitement, alter-ego, or you will have to change your ego to one of angst.

Now, the fun part: you have three MORE screws to loosen: those holding the helical to the focusing ring. Simply LOOSEN (not remove) them and you can adjust infinity focus easily. Be at a convenient 'infinity' venue where you can check this out (i use my window which faces skyscrapers about 1/4 mile away), and when you are convinced that you are at (or, better, very slighly BEYOND, infinity), lock those three helical screws again and put back the filter ring and logo ring. And then you are done with the fun.

If you were in Philadelphia I would do this in five minutes for you. If you cannot follow this call me at 215.569.4949. - David Lyga

thanks David, that is quite clear... And Europe is far away from Philadelphia

David Lyga · Jul 17, 2014

When you have loosened the three screws that hold the helicoid, that helicoid will be able to turn INDEPENDENTLY of the focus ring. It is at that time that you can focus properly (via helicoid, not via focus ring) and when you are satisfied with the focus, turn the now loose focus ring to infinity and tighten those three screws again. - David Lyga

leonche64 · Aug 5, 2015

I joined this site to say thank you for the information on adjusting this lens. I bought one today from a guy who was actually packing up to go out of business and pulled it out of a box for me. I got home and realized it was short of infinity. I worried for about 10 minutes until I came across this page. Thanks so much.

Leon from China.

Pentax Super Takumar 50mm 1.4 does not focus to infinity

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