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05-13-2013, 11:01 AM   #16
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I would test it out a few more times before trusting the adjustment on a real shoot.

In the FWIW department, I had something similar happen with my old Sigma 17-35/2.8 DG EX. I used it for years on all kinds of bodies (even film), and one day, it needed about +6 in focus adjustment on the K-5. That is a screw drive only lens.

05-13-2013, 12:20 PM   #17
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QuoteOriginally posted by GeneV Quote
I would test it out a few more times before trusting the adjustment on a real shoot.

In the FWIW department, I had something similar happen with my old Sigma 17-35/2.8 DG EX. I used it for years on all kinds of bodies (even film), and one day, it needed about +6 in focus adjustment on the K-5. That is a screw drive only lens.
To add to your FWIW department, I've also struggled with something similar to what the OP is having, and it turned out to be the camera (K-5) back focusing and not the lens. That is why there is a need at some point to isolate the problem being the lens or the camera.
05-13-2013, 12:26 PM   #18
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QuoteOriginally posted by stormtech Quote
To add to your FWIW department, I've also struggled with something similar to what the OP is having, and it turned out to be the camera (K-5) back focusing and not the lens. That is why there is a need at some point to isolate the problem being the lens or the camera.
Stan,

here's my summary of the situation as I have read both threads:
  • Previously K5 + 50-135 did NOT back focus
  • Presently both the K-5 and K-10 have back focus with this lens.
  • No other lenses have suddenly developed Back (or Front for that matter) focus per OPs reports
Given this set of conditions it would appear that it is the lens, and not the camera in this instance, that is having an issue.
05-13-2013, 01:37 PM   #19
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QuoteOriginally posted by Docrwm Quote
Stan,

here's my summary of the situation as I have read both threads:
  • Previously K5 + 50-135 did NOT back focus
  • Presently both the K-5 and K-10 have back focus with this lens.
  • No other lenses have suddenly developed Back (or Front for that matter) focus per OPs reports
Given this set of conditions it would appear that it is the lens, and not the camera in this instance, that is having an issue.
Thanks Doc - didn't realize there were two different threads on the matter.

05-13-2013, 01:48 PM   #20
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QuoteOriginally posted by stormtech Quote
Thanks Doc - didn't realize there were two different threads on the matter.
Yeah, I started this thread to find out what the symptoms of an SDM failure were, then the other post was referenced to....and it got back to the problem with my lens/camera(s)
05-13-2013, 01:52 PM   #21
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QuoteOriginally posted by BethC Quote
Yeah, I started this thread to find out what the symptoms of an SDM failure were, then the other post was referenced to....and it got back to the problem with my lens/camera(s)
I understand - just with my experience with these things it is a good idea to find the actual source of the problem. I went on for a couple months with a problem of back/front focusing thinking it could only be the lens when in fact my problem turned out to be the camera. What an ordeal!
05-13-2013, 02:07 PM   #22
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QuoteOriginally posted by stormtech Quote
I understand - just with my experience with these things it is a good idea to find the actual source of the problem. I went on for a couple months with a problem of back/front focusing thinking it could only be the lens when in fact my problem turned out to be the camera. What an ordeal!
Yeah after numerous tests this morning, I'm pretty sure it's that lens. Curious though, how did you find out it was a camera issue? Did you take it somewhere? Or test it yourself? How long to fix? Was it under warranty?
05-13-2013, 02:33 PM   #23
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QuoteOriginally posted by BethC Quote
Yeah after numerous tests this morning, I'm pretty sure it's that lens. Curious though, how did you find out it was a camera issue? Did you take it somewhere? Or test it yourself? How long to fix? Was it under warranty?
Lots and lots of testing! I am lucky enough to have 2 cameras (my K-5 plus my wife's K-x) which made it much easier. I also used Focus Tune to get as good a test of AF adjustment as I could. I finally found a consistent inconsistency (if you will) with lenses that performed well on the K-x, but would be off by the same degree on the K-5. I finally got to the point where I sent the camera off to CRIS under warranty with a description of my problem. According to the repair order, the camera was in fact back focusing - they adjusted it and it came back working perfectly. It was quite the learning experience - just wish I had figured out it was the camera and not any of my lenses a long time ago. The key to finding the answer was using Focus Tune as it is not only used for fine tune AF adjustment, but also gives you focus consistency tests along with aperture test (at which aperture is a lens the sharpest).

05-13-2013, 02:45 PM   #24
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QuoteOriginally posted by BethC Quote
Ok, so after doing the ruler test, I dialed in +9 and it seemed to front focus, then dialed it back to +7 and it seems to be focusing right now at least on the ruler. I was focusing on the line above the 16.
The way I usually do is by laying the ruler flat on the table, taking my tripod with the camera and positioning it next to the table. You should be shooting at the ruler at a roughly 45 degree angle. You need to have it well lit in order to get accurate focus. As nomadkng pointed out a ruler with darker markers may be more helpful as it aids in auto focus. Tripod is crucial in order to check the consistency of the adjusted lens.

QuoteOriginally posted by BethC Quote
Does that seem right now? and if it is right with that adjustment, is it stlll a good idea to send the lens back? would you trust this lens for some thing important like a wedding if it's had be adjusted this much?
Now it is a matter of repetition. Aim the center point at the mark where you want the focus and then switch to manual focus. Rotate to say infinity, switch to AF. AF and shoot. Do this like 5 times. Does it consistently lock focus on the right mark? If so, then it has been properly adjusted. Keep in mind you have a zoom lens. You need to perform this through the zoom range (say 50,75,100,125,135). I have never had the problem of having backfocus at one focal length but front focus at another, but i guess in theory at may be possible. In that case you would prob have to send it in. Otherwise, if AF is consistent then the adjustment is complete and you have nothing to worry about
05-13-2013, 02:49 PM   #25
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QuoteOriginally posted by BethC Quote
Yeah after numerous tests this morning, I'm pretty sure it's that lens. Curious though, how did you find out it was a camera issue? Did you take it somewhere? Or test it yourself? How long to fix? Was it under warranty?
If you send it into CRIS they would want both the camera and the lens. I am not sure how they handle back/front focus corrections, but I am speculating they may just dial it in just the same way you would if the lens just requires a minor adjustment (regardless of whether it is the lens or the body that has the problem). The other option would be to send it in with the K10, which does not have any AF adjustment (at least not unless you are in debug mode) and they would be "forced" to correct the lens i guess...
05-13-2013, 02:52 PM   #26
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QuoteOriginally posted by stormtech Quote
Lots and lots of testing! I am lucky enough to have 2 cameras (my K-5 plus my wife's K-x) which made it much easier. I also used Focus Tune to get as good a test of AF adjustment as I could. I finally found a consistent inconsistency (if you will) with lenses that performed well on the K-x, but would be off by the same degree on the K-5. I finally got to the point where I sent the camera off to CRIS under warranty with a description of my problem. According to the repair order, the camera was in fact back focusing - they adjusted it and it came back working perfectly. It was quite the learning experience - just wish I had figured out it was the camera and not any of my lenses a long time ago. The key to finding the answer was using Focus Tune as it is not only used for fine tune AF adjustment, but also gives you focus consistency tests along with aperture test (at which aperture is a lens the sharpest).
Mine was in fact the lens. I have no idea what happened, it wasn't dropped (that I recall) but after the problem appeared on the K5, it also appeared on the K-x. So, now this lens will be only used on the K5 and K20d in AF mode.
05-13-2013, 02:54 PM   #27
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QuoteOriginally posted by GeneV Quote
Mine was in fact the lens. I have no idea what happened, it wasn't dropped (that I recall) but after the problem appeared on the K5, it also appeared on the K-x. So, now this lens will be only used on the K5 and K20d in AF mode.
Granted that it can very well be the lens. My only point was not to discount the camera being off also. That is why it is nice to have 2 cameras to use for testing as you and I both did (and BethC does also).
05-13-2013, 03:46 PM   #28
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Question: Have you tried LiveView and is it off too?
05-14-2013, 06:44 AM   #29
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I thought CDAF (Live view) does not have back/front focus issues?
05-14-2013, 06:51 AM   #30
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QuoteOriginally posted by Mikesul Quote
I thought CDAF (Live view) does not have back/front focus issues?
If there is a focus problem with CDAF then it is the lens.
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