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View Poll Results: Is this DA*16-50mm good or bad?
Keep it -- it's good. 2388.46%
Return it or send it in for repair. 311.54%
Voters: 26. You may not vote on this poll

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04-21-2008, 02:05 AM   #661
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Just take some pictures with it and observe corner sharpness and anything that might seem "odd" to you. Anything less but stellar performance (hence the * after DA ) is grounds for replacement.

04-21-2008, 03:56 AM   #662
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Are the problem apparent only at f2.8 or also f8 ?

I will take k100d + lens during lunch and try it.
04-21-2008, 04:06 AM   #663
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Post some samples, if you can; so that other members can post their thoughts as well.
04-24-2008, 01:54 AM   #664
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Here are the images

Could you please comment on two issues. First one is the focus it seems that my 16-50mm and k10d (v1.30) has backfocus at 16mm. 50mm is spot on. Other thing is the lens sharpness and whether this is what you expect from 16-50mm or whether I have lemon. Seems ok to me, cant really test infinity length pictures as lens is backfocusing quit a lot. I am going to take more pictures, this time some real shots

Focus

http://www.promodus.co.uk/temp/16_50_focus_16mm_f28.jpg
http://www.promodus.co.uk/temp/16_50_focus_50mm_f28.jpg

Wall test:

16mm
http://www.promodus.co.uk/temp/16_50_wall_16mm_f28.jpg
http://www.promodus.co.uk/temp/16_50_wall_16mm_f8.jpg

50mm
http://www.promodus.co.uk/temp/16_50_wall_50mm_f28.jpg
http://www.promodus.co.uk/temp/16_50_wall_50mm_f4.jpg
http://www.promodus.co.uk/temp/16_50_wall_50mm_f8.jpg

It seems to me that lens doesnt have decentering problem but maybe I am wrong as I dont know what to look for.

With backfocusing issue, would k10d service menu help and also would lens focus differently with k20d ?

Thanks.

04-24-2008, 04:59 AM   #665
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QuoteOriginally posted by feronovak Quote
Could you please comment on two issues. First one is the focus it seems that my 16-50mm and k10d (v1.30) has backfocus at 16mm. 50mm is spot on. Other thing is the lens sharpness and whether this is what you expect from 16-50mm or whether I have lemon. Seems ok to me, cant really test infinity length pictures as lens is backfocusing quit a lot. I am going to take more pictures, this time some real shots

Focus

http://www.promodus.co.uk/temp/16_50_focus_16mm_f28.jpg
http://www.promodus.co.uk/temp/16_50_focus_50mm_f28.jpg

Wall test:

16mm
http://www.promodus.co.uk/temp/16_50_wall_16mm_f28.jpg
http://www.promodus.co.uk/temp/16_50_wall_16mm_f8.jpg

50mm
http://www.promodus.co.uk/temp/16_50_wall_50mm_f28.jpg
http://www.promodus.co.uk/temp/16_50_wall_50mm_f4.jpg
http://www.promodus.co.uk/temp/16_50_wall_50mm_f8.jpg

It seems to me that lens doesnt have decentering problem but maybe I am wrong as I dont know what to look for.

With backfocusing issue, would k10d service menu help and also would lens focus differently with k20d ?

Thanks.
There is obvious lack of sharpness on the left side of the images compared to the right, particularly at f2.8. There are two possible explanations: 1) centering defect 2) camera sensor not parallel to the wall

If you feel the sensor was accurately placed in relation to the wall, then you should return this lens.
04-24-2008, 05:16 AM   #666
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QuoteOriginally posted by Tbear Quote
There is obvious lack of sharpness on the left side of the images compared to the right, particularly at f2.8.
Yep, and there also appears to be back focus at 16mm...
04-24-2008, 05:44 AM   #667
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This is shame, it's really unacceptable on Pentax side to have such a problems with professional lens.

I bought this lens for landscape and occasional corporate evenings/weddings and planned on getting 43mm and Metz m-48 flash but I might consider changing Pentax as my system. I do love Pentax handling, their bodies are the top of the line as far as user interface and handling but these terrible lens problems are really bad.

I have more shots with me, this time some real shots. What I know for sure is that this lens is unable to shoot infinity length pictures, on 16mm even on f8 it is very soft and unusable.
04-24-2008, 06:23 AM   #668
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I really wanted this lens, I wanted to love this lens and I spent money although I knew the risks. But this is really bad, my lens simply cant focus into infinity and getting to 16mm you cant focus into anything:

http://www.promodus.co.uk/temp/16mm_hand_bf_01.jpg
http://www.promodus.co.uk/temp/16mm_garden_bf_01.jpg
http://www.promodus.co.uk/temp/16mm_garden_bf_02_f28.jpg

Difference between f2.8 and f8

http://www.promodus.co.uk/temp/16mm_garden_bf_01_f28.jpg
http://www.promodus.co.uk/temp/16mm_garden_bf_01_f8.jpg

I need to see how it focus on k100d and on k20d but if this is result I will have to send it back.

Would you try to buy another one or what lens would you recommend?

04-24-2008, 11:35 AM   #669
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QuoteOriginally posted by feronovak Quote

With backfocusing issue, would k10d service menu help and also would lens focus differently with k20d ?

Thanks.
the k10d would actually have to be sent back to pentax to get cleared, the k10d has memory for 4 lenses which is only accessible through their software

the k20d has the menu included for 20 lenses...a nice touch by pentax.

looking at your pictures, i would have to say, send it in
04-25-2008, 05:22 AM   #670
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QuoteOriginally posted by feronovak Quote
I really wanted this lens, I wanted to love this lens and I spent money although I knew the risks. But this is really bad, my lens simply cant focus into infinity and getting to 16mm you cant focus into anything:

http://www.promodus.co.uk/temp/16mm_hand_bf_01.jpg
http://www.promodus.co.uk/temp/16mm_garden_bf_01.jpg
http://www.promodus.co.uk/temp/16mm_garden_bf_02_f28.jpg

Difference between f2.8 and f8

http://www.promodus.co.uk/temp/16mm_garden_bf_01_f28.jpg
http://www.promodus.co.uk/temp/16mm_garden_bf_01_f8.jpg

I need to see how it focus on k100d and on k20d but if this is result I will have to send it back.

Would you try to buy another one or what lens would you recommend?
I had to return two before I got one that was made properly. The lens is so good, that it was worth the hassle. Only you can make the decision of exchanging it or returning it.
04-29-2008, 10:50 AM   #671
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I have a bad DA 16-50 2.8. The problems seem to occur more as I have had the lens. I have had it too long to send back to Amazon (about 45 days). I am going to send it into Pentax for repair. Has anyone had good luck with them fixing a defective lens? Or do they replace? Anything I should know about their repair process that might be helpful?

Thanks.

Joe
04-29-2008, 11:33 AM   #672
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I think that Pentax has just replaced all of them Joe, and Welcome to Pentax Forums.
04-29-2008, 11:38 AM   #673
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QuoteOriginally posted by feronovak Quote
I might consider changing Pentax as my system. I do love Pentax handling, their bodies are the top of the line as far as user interface and handling but these terrible lens problems are really bad.
Granted Pentax should have never released this lens without ensuring the quality ahead of time.
However all the companies do the same sort of things.

I'd never consider switching brands just because of one BIG mistake, if the company makes any real effort to fix the problem.
Although if they make repeated mistakes like it I would.
04-29-2008, 12:06 PM   #674
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QuoteOriginally posted by little laker Quote
I think that Pentax has just replaced all of them...
That's interesting. They really can't be "fixed"? Mine is going back after I can properly document the flaws this weekend. Still a tad too dark when I get home from work to get good natural light test images. Will have to wait until mid-day Saturday.
04-29-2008, 01:26 PM   #675
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It has more to do with the K10D than the lens. I would have a software revision done on the K10D or test your 16-50 on a K20D. If you have access to a store try it out. I am quite certain that those problems will disappear. My shitty 21 Ltd and 16-50 on the K10D morphed in to two incredibly sharp lenses on my K20D's..

Ben
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