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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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01-19-2008, 07:22 PM   #271
Igilligan
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Hi Tbear

QuoteOriginally posted by Tbear Quote
Maybe I'm just pixel peeping but look at the print on the philosophy books at f2.8 (there is one in the upper left corner and one in the upper right corner). The words on the cover of the right book look noticeably blurry compared to the left. Again, maybe I'm just imagining things.
I just downloaded the pic and looked at it. I am not seeing anything noticeably different between the corner book shots. None of the small print looks tack sharp. But they seem evenly matched to me. At least on my monitor. But I am no expert.

gus

01-19-2008, 07:25 PM   #272
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My local camera store (Contact Photo Arts) has just started testing their mail order lenses and cameras before they send them out

Since they've started doing that they've discovered 2 sensors with dust on them, and cleaned them.

They'd rather find the problem themselves than have a disappointed customer on their hands.

I wish that all mail order stores would start this practice. I don't think that it takes 10 minutes per camera.
01-19-2008, 09:11 PM   #273
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QuoteOriginally posted by roscot Quote
The only thing that I have to say about this is, if Pentax expects to be able to compete with Canon and Nikon on a quality level, then there is no excuse for this type of QC problem, ESPECIALLY on a top of the line pro lens.
Check out some reviews of other manufacturers lenses, there are horror story lemon lenses in even the Canon L range, which are far more expensive than Pentax's * range.

Hell, look at Canon's latest top end pro BODY, it has significant focusing issues!
01-19-2008, 09:21 PM   #274
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QuoteOriginally posted by Maxington Quote

look at Canon's latest top end pro BODY, it has significant focusing issues!
I bring this up to my canon buddies every chance i get.

01-19-2008, 10:21 PM   #275
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QuoteQuote:
If my sensor was not parallel to the newspaper, I would have seen similar problems with both lenses.
Not necessarily - different lenses can have different depths of field at the same aperture. And the DA* lens is known for its very shallow DOF wide open. Perhaps the kit lens has more DOF at the same aperture? I don't think the test "proves" that one lens is defective (although it may well be). Only a carefully set up and measured test, with an absolutely flat target that is absolutely square-on to the sensor can "prove" it.
01-19-2008, 10:46 PM   #276
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If Pentax hadn't found anything wrong with it, they would have sent the same one back.
So Tbear must have been correct in his findings.
01-20-2008, 09:02 AM   #277
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QuoteOriginally posted by little laker Quote
If Pentax hadn't found anything wrong with it, they would have sent the same one back.
So Tbear must have been correct in his findings.
Thank you Stu, I could not have stated it better. It seems some people are in state of denial that there are so many DA* 16-50 lemons out there.
01-20-2008, 09:06 AM   #278
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QuoteOriginally posted by Derridale Quote
Not necessarily - different lenses can have different depths of field at the same aperture. And the DA* lens is known for its very shallow DOF wide open. Perhaps the kit lens has more DOF at the same aperture? I don't think the test "proves" that one lens is defective (although it may well be). Only a carefully set up and measured test, with an absolutely flat target that is absolutely square-on to the sensor can "prove" it.
Even if they had different DOFs at same aperture (which I doubt), the fact remains that the kit lens demonstrated exactly equal sharpness on the left and right sides, while the * lens demonstrated markedly poorer sharpness on the left compared to the right. If you think those results are due to different DOFs, then I'm afraid I will never convince you. Thankfully, Pentax seemed to agree with my findings as they are sending me a new lens.

01-20-2008, 12:53 PM   #279
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QuoteOriginally posted by Tbear Quote
Maybe I'm just pixel peeping but look at the print on the philosophy books at f2.8 (there is one in the upper left corner and one in the upper right corner). The words on the cover of the right book look noticeably blurry compared to the left. Again, maybe I'm just imagining things.
I notice now that this setup with 16mm has inherent problems. It should have been closer so that only test chart was in sight, but because of my in-camera flash shadow I backed a little (actually zoomed out after 50mm). Those books are for paper weight only. At f/2.8 the in focus depth is so shallow that those books are perhaps not in focus plain any more(?). Most of the books are about 2 inches thick (chemistry book ca. 2,2 inches). I am sorry for the confusion... if not misleading you guys :-(

EDIT: Added two more 16mm f/2.8 pics (part of a bookshelf and one from the test chart).

Last edited by gawan; 01-20-2008 at 03:16 PM.
01-20-2008, 12:55 PM   #280
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QuoteOriginally posted by Ed in GA Quote
If you'll notice when you autofocus with the lens using SDM, the focus ring does not move nor does the head of the lens move in and out.

That fact that you can move the ring beyond the stops is very normal. This concerned me as well when I received mine. I call Pentax Tech support and they explained it to me.
Thank you, you relieved me from unnecessary worries

Last edited by gawan; 01-20-2008 at 03:17 PM. Reason: typo
01-20-2008, 01:02 PM   #281
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I added now some photos from my first walk around with this lens, they are taken in cloudy weather or in the few hours of sun light this evening, your evaluation will be very much appreciated. The exposure/focal length/ISO figures are included in the file names.

EDIT: All pictures are simply exported from RAW via Lightroom. No special processing except adjusting brightness in some.

IMHO they are not too bad (in IQ sense), but not stellar either. I'm not sure if I just expect too much from this lens, or what to expect.

I have still about 7 days to decide if I were to keep this or not.

Last edited by gawan; 01-20-2008 at 03:00 PM.
01-20-2008, 02:29 PM   #282
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QuoteOriginally posted by gawan Quote
I added now some photos from my first walk around with this lens, they are taken in cloudy weather or in the few hours of sun light this evening, your evaluation will be very much appreciated. The exposure/focal length/ISO figures are included in the file names.

IMHO they are not too bad (in IQ sense), but not stellar either. I'm not sure if I just expect too much from this lens, or what to expect.

I have still about 7 days to decide if I were to keep this or not.
One cannot expect it to keep up with limited primes, but it should be pretty darn impressive as a zoom, especially for the money.
01-20-2008, 02:53 PM   #283
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QuoteOriginally posted by Tbear Quote
One cannot expect it to keep up with limited primes, but it should be pretty darn impressive as a zoom, especially for the money.
Yep, this one at least suits my purposes quite well, and it feels so great! If I keep this, I am thinking to acquire DA * 50-135 and perhaps Sigma 100-300,f/4, so I should eventually be covered quite well with zooms. (I have DA 35 and Sigma 70 1:1 macro as primes so far).
01-20-2008, 10:57 PM   #284
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I just got my 16-50mm too. When yours focuses is there a slight knocking noise?

I haven't done any real tests with my lens, but I guess I should at least do the newspaper. But the noise that it makes did kind of worry me. Anyone else have the same problem?
01-21-2008, 01:25 AM   #285
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QuoteOriginally posted by superbass Quote
I just got my 16-50mm too. When yours focuses is there a slight knocking noise?

I haven't done any real tests with my lens, but I guess I should at least do the newspaper. But the noise that it makes did kind of worry me. Anyone else have the same problem?
I can hardly hear the focusing action, but what I hear (kinda low noise tapping), sounds normal. SDM being a silent one, does not make it absolutely noiseless.
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