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10-16-2007, 10:40 PM   #1
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16-50... Argghhh

After a long two-month FedEx saga (separate story), I finally get my 16-50 and 50-135. The tele is fine but 16-50 is BOTH decentered and backfocuses. Due to timing, I cannot return them anymore but back to Pentax it goes...

Has anyone sent their lens to Pentax USA? How long does it take?

10-17-2007, 03:27 PM   #2
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I'm interested in the same answer since I received my DA* 16-50 today and have blurry photos at f2.8. I can send it back to the vendor, but I figure - what good is it if I just get another "problem" lens from them. I'd like to know how good service is at Pentax and if I'd be better off sending it there under warranty.

FWIW here are the photos. Test were done on a tripod taking 5 frames at each setting. At each setting the quality of the photos was consistent.

Focused nicely on the top of the tree - 100% crop f8.0 @ 50mm


Out of focus - 100% crop f2.8 @ 50mm


I'd really appreciate any insight any members can give.

Last edited by rogerstg; 10-18-2007 at 04:32 PM. Reason: grammar
10-17-2007, 05:27 PM   #3
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Not sure what to say about it, but both of those photos look out of focus to me...
10-17-2007, 06:05 PM   #4
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Yikes!

It's incredible! The apparent percentage of duds in this model lens is hard to believe. Is it a design flaw or are they being assembled in the back of a coffe shop?

10-17-2007, 07:44 PM   #5
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QuoteOriginally posted by rogerstg Quote
I'm interested in the same answer since I received my DA* 16-50 today and have blurry photos at f2.8. I can send it back to the vendor, but I figure - what good is it if I just get another "problem" lens from them. I'd like to know how good service is at Pentax and if I'd be better off sending it there under warranty.


I'd really appreciate any insight any members can give.
My version, bought in August performed equally poorly; I debated my options and decided to return the lens for a refund. I did not want to take a chance on Pentax's ability to repair it and risk getting stuck with a $900.00 paper weight. Best wishes.
10-17-2007, 08:15 PM   #6
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I thought that these were SUPPOSED to be produced with the best quality under strict production guidlines??????

I need someone to defend this??? Is this the real reason why old Pentax glass sells for such a premium????
10-17-2007, 08:23 PM   #7
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This is what my copy produces.
Like I said earlier, unfortunately in my case, returning is not an option.

QuoteOriginally posted by rogerstg Quote
I'm interested in the same answer since I received my DA* 16-50 today and have blurry photos at f2.8. I can send it back to the vendor, but I figure - what good is it if I just get another "problem" lens from them. I'd like to know how good service is at Pentax and if I'd be better off sending it there under warranty.

FWIW here are the photos. Test were done on a tripod taking 5 frames at each setting. At each setting the quality of the photos were consistent.

Focused nicely on the top of the tree - 100% crop f8.0 @ 50mm


Out of focus - 100% crop f2.8 @ 50mm


I'd really appreciate any insight any members can give.


10-17-2007, 08:27 PM   #8
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QuoteOriginally posted by herzzreh Quote
This is what my copy produces.
Like I said earlier, unfortunately in my case, returning is not an option.
Earlier this fall, I sent a lens (not a DA*) to Pentax for a focussing defect. They had it for about a month not including shipping time. I called them first on the phone; they were quite helpful. I would recommend calling first to talk with someone. Best wishes.
10-17-2007, 09:29 PM   #9
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QuoteOriginally posted by thePiRaTE!! Quote
Not sure what to say about it, but both of those photos look out of focus to me...
I think I'd need more pixels for the top shot to be any better. After all, it is less than 2% of the original as shown below in the full test shot - resized of course. The test shots with the 18-55 kit lens was not as good as the focused 16-50.


Last edited by rogerstg; 10-18-2007 at 09:25 AM.
10-18-2007, 04:05 PM   #10
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QuoteOriginally posted by rogerstg Quote
I'm interested in the same answer since I received my DA* 16-50 today and have blurry photos at f2.8. I can send it back to the vendor, but I figure - what good is it if I just get another "problem" lens from them. I'd like to know how good service is at Pentax and if I'd be better off sending it there under warranty.

FWIW here are the photos. Test were done on a tripod taking 5 frames at each setting. At each setting the quality of the photos were consistent.


I'd really appreciate any insight any members can give.
I would manually focus the same or similar shot to see if the results are any better.

This way, you eliminate the AF system as being all or part of the problem.

If the results look ok (they will not match the f8 shot, as I am sure you must know) or noticeably better, then the lens is not the problem, or at least not the entire problem.

You might also try shooting at objects closer in to see if the problem is only when focused at or near infinity at the wide open aperture.

These are my only suggestions at this point.

I just received my copy of the 16-50 and have not been able to take it out in daylight as of yet. I shot a few indoor pics at f4 of a PZ-1 I was selling to another member here and they were very sharp. Hopefully, I will give it a workout this weekend.

Ray
10-18-2007, 08:58 PM   #11
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When I MF, the results are better. I don't think it's the lens, the the AF system that's malfunctioning. This is the same behaviour that my old Sigma 24-70 EX exhibited. When it got the focus (or you MF), it was superb optically, but unfortunately, using AF it missed 85% of the shots.

QuoteOriginally posted by Ray Pulley Quote
I would manually focus the same or similar shot to see if the results are any better.

This way, you eliminate the AF system as being all or part of the problem.

If the results look ok (they will not match the f8 shot, as I am sure you must know) or noticeably better, then the lens is not the problem, or at least not the entire problem.

You might also try shooting at objects closer in to see if the problem is only when focused at or near infinity at the wide open aperture.

These are my only suggestions at this point.

I just received my copy of the 16-50 and have not been able to take it out in daylight as of yet. I shot a few indoor pics at f4 of a PZ-1 I was selling to another member here and they were very sharp. Hopefully, I will give it a workout this weekend.

Ray
10-19-2007, 06:27 AM   #12
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QuoteOriginally posted by Ray Pulley Quote
I would manually focus the same or similar shot to see if the results are any better.

This way, you eliminate the AF system as being all or part of the problem.

If the results look ok (they will not match the f8 shot, as I am sure you must know) or noticeably better, then the lens is not the problem, or at least not the entire problem.

You might also try shooting at objects closer in to see if the problem is only when focused at or near infinity at the wide open aperture.

These are my only suggestions at this point.

I just received my copy of the 16-50 and have not been able to take it out in daylight as of yet. I shot a few indoor pics at f4 of a PZ-1 I was selling to another member here and they were very sharp. Hopefully, I will give it a workout this weekend.

Ray
I took similar test shots at appx 20 ft and did not see a focusing problem. The lens is a bit softer at 2.8, but that was only slightly noticeable when viewing small writing at 100%. I have no complaints in this area.

I tried manually focusing and got better results. They looked the same as the f5.6 AF shots. That pretty much eliminates the optics as the problem. The question remaining is whether it is the AF system within the lens (calibration?) or within the camera body.

Since the camera focuses properly with other lenses, and this lens in settings other than infinity, I suspect that it is not the camera's AF system.

While I'd classify myself as an experienced amateur in manual and semi manual SLR photography, I'm a newbie with DSLR AF systems and what I should expect. I wonder if these results are within reason? Looking at the uncropped pics on my monitor (~ 11x14" at 30%) of the good v bad shots, I discern a slight difference, yet at 100% the results are obvious, as shown above.

Any thoughts from experienced DSLR users of premium lenses?
10-19-2007, 08:08 AM   #13
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QuoteOriginally posted by rogerstg Quote
I took similar test shots at appx 20 ft and did not see a focusing problem. The lens is a bit softer at 2.8, but that was only slightly noticeable when viewing small writing at 100%. I have no complaints in this area.

I tried manually focusing and got better results. They looked the same as the f5.6 AF shots. That pretty much eliminates the optics as the problem. The question remaining is whether it is the AF system within the lens (calibration?) or within the camera body.

Since the camera focuses properly with other lenses, and this lens in settings other than infinity, I suspect that it is not the camera's AF system.

While I'd classify myself as an experienced amateur in manual and semi manual SLR photography, I'm a newbie with DSLR AF systems and what I should expect. I wonder if these results are within reason? Looking at the uncropped pics on my monitor (~ 11x14" at 30%) of the good v bad shots, I discern a slight difference, yet at 100% the results are obvious, as shown above.

Any thoughts from experienced DSLR users of premium lenses?
I have found AF to be a hit or miss thing with Pentax DSLRs. My film cameras were better in some ways, but worse in low light as they had older generation AF systems.

I have a 31ltd that works fine on my DS and K100D but is almost never in focus on the K10d's I own. My 16-45 seems good on all bodies as does my 50-200. It is quite frustrating.

It is also harder to manually focus using the APS sized viewfinder and only the matte screen, so that isn't always a solution either. I have considered a katzeye screen, but you lose the spot meter and I use that feature quite often, so that will not work either.

To be fair, if you visit the brandx forums at look at Nikon and Canon, they have the same problems although they have a better reputation for focusing properly. There are many reports of lens to lens focusing issues and other AF problems on non-Pentax bodies so I am not sure if Pentax is really that much worse in terms of focus accuracy. I think the other brands, and even some older Pentax bodies do focus faster than Pentax however.

I think Pentax can calibrate a certain number of lenses to your body, but I am not 100% certain of this as there is no official information about that service. I seem to recall that Pentax offered to do this for Ben when he had some focus issues with his K10Ds. You might try contacting Pentax to see what they can do. I would call them as I have never received a single response to amy email inquiry I have ever sent them when I have had problems with my equipment.

Ray
10-19-2007, 10:23 AM   #14
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QuoteOriginally posted by rogerstg Quote
I took similar test shots at appx 20 ft and did not see a focusing problem. The lens is a bit softer at 2.8, but that was only slightly noticeable when viewing small writing at 100%. I have no complaints in this area.

I tried manually focusing and got better results. They looked the same as the f5.6 AF shots. That pretty much eliminates the optics as the problem. The question remaining is whether it is the AF system within the lens (calibration?) or within the camera body.

Since the camera focuses properly with other lenses, and this lens in settings other than infinity, I suspect that it is not the camera's AF system.

While I'd classify myself as an experienced amateur in manual and semi manual SLR photography, I'm a newbie with DSLR AF systems and what I should expect. I wonder if these results are within reason? Looking at the uncropped pics on my monitor (~ 11x14" at 30%) of the good v bad shots, I discern a slight difference, yet at 100% the results are obvious, as shown above.

Any thoughts from experienced DSLR users of premium lenses?
Just to put things into perspective, here's and interesting read on some ongoing Canon AF issues:

Rob Galbraith DPI: An analysis of EOS-1D Mark III autofocus performance

Just think how frustrated you would be if you paid $8,000 for a camera that could not focus properly with any lens and 5 months later it has not been fixed...

Ray
10-19-2007, 10:44 AM   #15
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i have sent my K10D and K100D in for servicing to Pentax i say thay that are GRATE to deal with and the people on the phone are GRATE but the 4 weak tunaround is a bit frustrating BUT i do belive Pentax has the BEST costmer service i have EVER delt with not just cameras but other co.s also
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