Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-14-2016, 02:21 AM   #1
Forum Member




Join Date: Jul 2016
Posts: 61
Pentax adapter, no focus to infinity with Takumar lenses

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!

07-14-2016, 03:07 AM   #2
Veteran Member




Join Date: Jun 2013
Location: Newcastle
Photos: Gallery | Albums
Posts: 1,954
That is weird.

How are you determining the fail in infinity focus? By the photographs taken or the focus as seen through the viewfinder?
07-14-2016, 04:28 AM   #3
Forum Member




Join Date: Jul 2016
Posts: 61
Original Poster
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.
07-14-2016, 04:41 AM   #4
Veteran Member




Join Date: Jun 2013
Location: Newcastle
Photos: Gallery | Albums
Posts: 1,954
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

07-14-2016, 04:56 AM   #5
Pentaxian
Medex's Avatar

Join Date: May 2013
Posts: 567
QuoteOriginally posted by Roquefort Quote
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
07-14-2016, 06:37 AM   #6
Forum Member




Join Date: Jul 2016
Posts: 61
Original Poster
QuoteOriginally posted by Medex Quote
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.
07-14-2016, 06:43 AM   #7
Veteran Member




Join Date: Jun 2013
Location: Newcastle
Photos: Gallery | Albums
Posts: 1,954
Ah well done, problem solved. The focus screen or even the mirror.

07-14-2016, 09:20 AM   #8
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 41,480
QuoteOriginally posted by Roquefort Quote
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
07-16-2016, 11:11 AM   #9
Loyal Site Supporter
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Paris, TN
Photos: Gallery | Albums
Posts: 3,192
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.
07-20-2016, 03:39 AM   #10
Forum Member




Join Date: Jul 2016
Posts: 61
Original Poster
QuoteOriginally posted by stevebrot Quote
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!
08-01-2016, 09:46 AM   #11
Site Supporter
Site Supporter
todd's Avatar

Join Date: Jul 2008
Location: Basement
Photos: Gallery
Posts: 6,411
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..

Last edited by todd; 08-01-2016 at 10:06 AM.
08-01-2016, 09:42 PM   #12
Loyal Site Supporter
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Paris, TN
Photos: Gallery | Albums
Posts: 3,192
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.
08-02-2016, 09:53 AM   #13
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 41,480
QuoteOriginally posted by pacerr Quote
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.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
adapter, focus, infinity, lenses, pentax, takumar, tripod
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-x no longer can focus to infinity, any lens frankfrank Troubleshooting and Beginner Help 6 06-23-2016 11:31 AM
SMC Pentax 1:1.8/55 K-mount, no Infinity Focus timmijo Pentax SLR Lens Discussion 9 12-28-2015 05:58 PM
Focus ring offset or no infinity focus? (Mamiya 55mm F/1.4) Doundounba Pentax SLR Lens Discussion 6 12-22-2015 07:59 PM
Has anyone tried Ebay Pentax to Nikon Infinity Focus adapter? enyceckk Pentax DSLR Discussion 5 11-09-2015 10:13 PM
How to adjust infinity focus on Takumar 35MM 3.5 bornamachine Troubleshooting and Beginner Help 20 06-30-2013 01:54 AM



All times are GMT -7. The time now is 05:20 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top