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05-07-2013, 01:06 PM   #1
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Pentax 18-135mm does not focus to infinity below 33mm

My Pentax 18-135mm lens doesn't seem to focus to infinity at focal lengths below about 33mm. The problem is at its worst at around 20mm where the lens doesn't focus farther than 5-6 feet and must be stopped down to as far as f/9 to compensate. Does anyone else have this problem, and what should I do?

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05-07-2013, 01:18 PM   #2
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Yeah, I've had it happen with wide-angle lenses like the 12-24mm or FA 20. Seems to be a weakness of the Pentax AF system. Try doing a focus calibration maybe?

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05-07-2013, 01:27 PM   #3
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That's not the case. The softness at the longest focusing distance is obvious in Live View.

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05-08-2013, 10:43 AM   #4
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Bump: Anyone else with this issue?

05-09-2013, 07:21 PM   #5
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Bump.
05-10-2013, 01:28 AM   #6
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Just to clarify: Does it "merely" not autofocus to infinity or does or not focus to infinity at all, even with focused manually?

Assuming you have other lenses in that range that focus to infinity fine, the 18-135 probably needs to be adjusted. That said, it might also be an issue with mount position on the camera. I am under the impression that many of my old manual primes are just a hair short of true infinity (as is my DA L 18-55 at the wide end), so I suppose the registration distance on my K-x might be a smidgen bigger than 45.46 mm. I'm talking maybe 30..50m instead of infinity in most cases, but that's enough with today's pixel peeping abilities.
05-10-2013, 05:41 AM   #7
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@52mm: The lens does not focus to infinity at all. The phase detection system tries to go past the infinity stop and fails; manually focusing the lens in Live View is no better.

--DragonLord
07-14-2013, 06:42 PM   #8
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Sorry for the late bump, but I ended up sending this lens in along with my K-5 and 50mm macro (in the same box) for repair. The lens is out of warranty.

Of the three items, the 18-135mm is the only one that is out of warranty; as of this writing, I have not yet received an estimate for repair. The 50mm is under the service warranty (from a previous out-of-warranty repair attempt) with a problem with autofocus accuracy on both my K-r and K-5 as well as an intermittent aperture ring issue where it electronically drops out of the "A" position despite it having never moved from that position. The K-5 was sent in under the Pentax extended warranty (with about 20 months left) for the front rubber grip being slightly loose and peeling off near the front e-dial. The grip has been replaced and secured and the camera is on its way back.

Edit: Estimate of $123 (+$18 S&H) approved on the DA 18-135mm lens to correct the infinity focus issue.

--DragonLord


Last edited by bwDraco; 07-16-2013 at 02:49 PM.
07-22-2013, 03:05 PM   #9
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The lens has been adjusted for infinity focus and decentering has been corrected:

QuoteQuote:
*FOCUS RING IS DESIGNED TO SLIP PAST FOCUS STOPS
REPAIR COMES WITH A 6 MONTH SERVICE WARRANTY
ADJUSTED INFINITY FOCUS
ADJUSTED OPTICS TO OPTIMUM FOCAL POINT TO CORRECT VIGNETTING ON TOP LEFT SIDE
VERIFIED PROPER FOCUS AT NEAR AND INFINITY TARGETS ON ALL FOCAL LENGTHS.
CLEANED AND CHECKED TO MANUFACTURER'S SPECIFICATIONS
--DragonLord
07-29-2013, 12:00 PM   #10
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I got the lens back, and the infinity focus issue has been resolved. The decentering was partially (not fully) corrected, but the lens works fine to me. Then again, this lens has seen quite extensive wear over the past year and a half or so...

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