[Roquefort]

Hey,

I have a problem with my Pentax adapter where I can't get any of my Takumar lenses (35, 55, 135 and 300mm) to focus to infinity. I'm using an ME Super and have also tried with an MG, same problem.

Now I've looked for a solution but in most cases I've found it was a wrong adapter being used, which shouldn't be a problem here since I'm using the official Pentax one. Weirdly, with a Pentacon lens I tried I don't have this problem, and the Takumar lenses work fine on a Praktica body (screw mount so no adapter) as well. So it seems there is something about the adapter that prevents it from working properly with the lenses that it was designed to work with.

Has anyone had a similar problem? Is there some way to adjust the adapter or should I look for a new one?

Thanks in advance!

[Wild Mark]

That is weird.

How are you determining the fail in infinity focus? By the photographs taken or the focus as seen through the viewfinder?

[Roquefort]

The split prism doesn't line up like it should. The difference is quite small but noticeable. I'm not entirely sure if the focusing is a bit off at all distances or if it's just impossible to reach infinity. Long distance photos seem sharp enough to me which would suggest it's the former.

[Wild Mark]

Hmmmm interesting. I will have a look tomorrow with my own gear to see what it looks like. Might be a quirk of the lens - camera combo

[Medex]

Hey,

I have a problem with my Pentax adapter where I can't get any of my Takumar lenses (35, 55, 135 and 300mm) to focus to infinity. I'm using an ME Super and have also tried with an MG, same problem.

Now I've looked for a solution but in most cases I've found it was a wrong adapter being used, which shouldn't be a problem here since I'm using the official Pentax one. Weirdly, with a Pentacon lens I tried I don't have this problem, and the Takumar lenses work fine on a Praktica body (screw mount so no adapter) as well. So it seems there is something about the adapter that prevents it from working properly with the lenses that it was designed to work with.

Has anyone had a similar problem? Is there some way to adjust the adapter or should I look for a new one?

Thanks in advance!

try to focus your m42 Takumar without m42-PK adapter, just holding the lens with your hand. If the problem persists, the adapter is OK

[Roquefort]

try to focus your m42 Takumar without m42-PK adapter, just holding the lens with your hand. If the problem persists, the adapter is OK

The problem's still there. I guess there must be something wrong with the focus screen itself, cause I found a bayonet lens to try and it's the same there. I'll take it to the shop and see if something can be done about it.

[Wild Mark]

Ah well done, problem solved. The focus screen or even the mirror.

[stevebrot]

The problem's still there. I guess there must be something wrong with the focus screen itself, cause I found a bayonet lens to try and it's the same there. I'll take it to the shop and see if something can be done about it.

Two cameras (MG and ME Super)...same problem? Focus screen/lens flange calibration issues are not unknown, but fairly unusual for cameras of that vintage and to have it on two bodies is highly unlikely.

The gold standard is to check focus against ground glass (or similar) at the film plane with a magnifying loupe. Lacking a ground glass slide, you can make do with a length of "magic" type adhesive tape and magnifier of some sort. Test the ground glass against the split image at both near and far distance. In all likelihood, the infinity stops for both your lenses are a little off.


Steve

[pacerr]

Verify that the adapter mounts flush with the face of the camera mount and seats flush against the lens base.

Sounds as though you have a tiny bit of 'extension tube' effect when using the adapter. Check variation in minimum focus distance as well.

[Roquefort]

The gold standard is to check focus against ground glass (or similar) at the film plane with a magnifying loupe. Lacking a ground glass slide, you can make do with a length of "magic" type adhesive tape and magnifier of some sort. Test the ground glass against the split image at both near and far distance. In all likelihood, the infinity stops for both your lenses are a little off.

I'll have to try that some time, after some more testing I think it might be the lenses after all.

Thanks for the replies everyone!

[todd]

I've been exploring this issue as well... Arranged to buy a Super Takumar 24mm locally and had a week before meeting him, so was doing some reading on the lens ahead of time and noticed this page. So sure enough when I met the seller last night and tried the lens on my K1, it seemed clearly deficient at infinity. The seller also had a 20mm Takumar that I am considering buying, so I tried that lens with the same adapter and it either did focus at infinity, or was at least much closer. I went ahead and bought the 24mm and have more testing to do, but am debating trying a surgery as described in that page linked above.


Edit: FWIW, I went out back for a quick test that occured to me... One thing I've always done (have always used the cheap adapters, btw...) is screw the lenses down solid whenever I shoot with M42's. I decided to slightly unscrew the lens to see if it had any effect, and sure enough the farthest thing I could focus on got noticeably sharper at infinity. Had to get back to my day job but will be testing this more later..

[pacerr]

I'm always curious exactly what they mean when folks say a lens won't "focus at infinity".

Does the lens focus sharply at ANY distance? I've 'fixed' two older lenses that just needed the rear element snugged up.

Does the focus ring stop turning BEFORE achieving sharp focus at the far horizon and/or focus significantly closer than design min focus distance?

- Something may be acting like a very thin extension ring. Check for a snug fit of the lens base against the camera mount.

Or it may be miss-adjusted. Does the lens focus ring stop before, or continue to turn beyond, the point of sharp focus at the far horizon?

- The point at which the focus ring stops is adjustable and may simply need to be re-set to match the infinity symbol - that's just a necessary calibration to accommodate variables in manufacturing. Often accomplished via screws under the rubber focusing ring sleeve.

[stevebrot]

I'm always curious exactly what they mean when folks say a lens won't "focus at infinity".

Does the lens focus sharply at ANY distance?

Often enough, when that sort of thing is posted on this site, the user is not sure. I remember one user in particular whose lens was defective (not really sharp at any distance), but who would only do focus evaluation at infinity.

Usually, the problem is that the focus ring alignment* has been messed with at some point (adapted to Nikon?) or the lens is simply not proper due damage or botched service attempt.


Steve

* Depending on the lens, the hard stop may be part of the focus ring rather than the actual focus mechanism.