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10-17-2017, 09:56 PM   #1
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Manual focus lenses with infinity focus issues - anyone else encountering them?

I recently acquired a lovely SMC K 17 f4 fisheye which works well on my K-1 (review to come) except it does not make it to infinity focus With the lens set on infinity, actual in focus point is about 6m away.
I'm planning to adjust this lens (have done so with a K 28 f3.5 with the same problem recently and it made a big difference to how it performed) and then had one of those moments... "what if something in my K-1 is out of spec?". So I whipped out my K-5 and K-01 and tested those to find:
  • Can't reach infinity with K-5 (but not quite as bad as K-1)
  • The K-01 is very close to infinity focus but still a tiny bit out

So clearly there is some variations in mount tolerances between cameras (as there is in lenses themselves) but most likely my K-1 is not the problem.
This is 3rd lens I have experienced problems with:
  • Samyang 8mm fisheye - but then this lens is well known for this problem and relatively easy to adjust
  • SMC K 28 f3.5. Definitely short of infinity on K-1 and is likely the reason why I was a little dissapointed with it on the K-5
  • SMC K 17mm f4 fisheye as mentioned

So I'm assuming there must be other photographers using these older manual lenses that run in to these sort of problems - or have I just been a bit unlucky?

10-17-2017, 10:46 PM   #2
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I've got a Super Takumar 50/F1.4 that won't focus at infinity. I mainly use it for portraits so it's not an issue.

Dan.
10-17-2017, 11:21 PM   #3
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Same experience here.
I was surprised that my M85/2 was 'way out' on the K1 on reaching infinity, as well as 2 other old lenses being of varying degrees short of infinity.
These had no such issues since K7, K5, K20.

I'd suspect either the 'golden unit' they have in the plant is changed (used to check such tolerances), or the FF is more stringent on this.

Anyway, to be safe, its good to check all lenses before important use with a new camera.
I had all of my affected lenses adjusted.
10-17-2017, 11:47 PM   #4
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Original Poster
I have seen that

QuoteOriginally posted by dosdan Quote
I've got a Super Takumar 50/F1.4 that won't focus at infinity. I mainly use it for portraits so it's not an issue.
Dan.
Thanks Dan.
I have seen similar problems with cheaper M42 adaptors but I'm guessing that you know about that and its not the case for you.

---------- Post added 10-18-2017 at 07:49 PM ----------

QuoteOriginally posted by pinholecam Quote
Same experience here.
I was surprised that my M85/2 was 'way out' on the K1 on reaching infinity, as well as 2 other old lenses being of varying degrees short of infinity.
These had no such issues since K7, K5, K20.

I'd suspect either the 'golden unit' they have in the plant is changed (used to check such tolerances), or the FF is more stringent on this.

Anyway, to be safe, its good to check all lenses before important use with a new camera.
I had all of my affected lenses adjusted.
Thanks for letting me know.
You may well be right and I suspect that with increased use of plastics that perhaps mechanical tolerances are bit wider than they used to be - hence modern lenses being capable of focusing past infinity to allow for errors.


Last edited by kiwi_jono; 10-17-2017 at 11:56 PM.
10-18-2017, 04:04 AM   #5
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QuoteOriginally posted by kiwi_jono Quote
I have seen similar problems with cheaper M42 adaptors but I'm guessing that you know about that and its not the case for you.
I'm not using a flange-type M42 adaptor that adds extra thickness between the lens and the camera body. I'm using the flush-type adaptor which adds no extra thickness.

Dan.

Last edited by dosdan; 10-18-2017 at 04:18 AM.
10-18-2017, 08:14 AM - 1 Like   #6
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QuoteOriginally posted by kiwi_jono Quote
So I'm assuming there must be other photographers using these older manual lenses that run in to these sort of problems - or have I just been a bit unlucky?
Do you have an old Pentax K-mount film body to test the K Series lenses on? That will eliminate the lenses for sure. I've been using my K28/3.5 for over 40 years with zero issues, so my guess it's the K-1's K-mount.

Phil.
10-18-2017, 09:38 AM   #7
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The Samyang/Rokinon wide angle lenses are notorious for this issue. It's a big problem in astrophotography, where you're always at infinity. They can be adjusted, unless the problem is that even after adjustment, you can't get to infinity.
I also had an Irix lens that had this issue...that would have been even easier to adjust, but the lens was also a little decentered, so I sent it back.
10-18-2017, 09:56 AM   #8
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I don't care about infinity focus.

My photography these days is subject focused with limited depth of field. The subjects that I focus on are at either close or at mid-range distances.

When I used to do focus stacking when doing landscapes in the past, I would sometimes take a shot that focused at infinity. But I don't do focus stacking anymore.

10-18-2017, 01:19 PM   #9
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QuoteOriginally posted by gofour3 Quote
Do you have an old Pentax K-mount film body to test the K Series lenses on? That will eliminate the lenses for sure. I've been using my K28/3.5 for over 40 years with zero issues, so my guess it's the K-1's K-mount.

Phil.
Great suggestion Phil - I'm surprised I did not think to check!

I just tried my 17mm fisheye and K 28 (already adjusted) on my ME Super. I just used the split screen focusing aid but I'm pretty confident thats spot on...
  • The 17mm is definitely focussing short of infinity.
  • The K28 is spot on right (and remember I have adjusted that already)

So I'm concluding that the lenses were indeed out and its not so much the differences in camera (although I do see some small differences between the DSLRs).
My guess is that on film, you would not notice the error for the often closer subjects and typical small print sizes (like 5 x 7). However on deeper landscapes with bigger prints, it would have been apparent but perhaps written off as murky day or a limitation of the lens. On K-1 photos its noticable viewing full screen on my monitor (but then thats a lot bigger than a 5 x 7).

So I just have to get on with it and tweak it.
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