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07-30-2008, 07:55 PM   #136
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9029404 Purchased 7/22/08 from B&H, received 7/24/08, seems to work perfectly. It is quite a piece of equipment, very impressive thus far.

08-01-2008, 02:42 AM   #137
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My new one...

Just got my k20d and 16-50mm lens, and I'm not sure about this one... take a look.

Downresed version followed by an image of 300x300 crops from all corners, the center, and the centers of all 4 edges. I may need to do this again using all-text pages, but take a look and see what you think.

At 50mm


crops




At 28mm


crops




At 16mm


crops




Like I said, I probably need to try again with a page entirely of text, so any other ideas on improving my methodology would be more than welcome.

Thanks
08-01-2008, 09:01 AM   #138
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I notice the barrel distortion, so I suspect that this is at 16mm. You are indoors, so I also suspect that you are at f/2.8. You are obviously close to the target. You have found the ideal situation to mercilessly show up the flaws in a wide angle lens. I was unable to open your flickr site to examine the full size image and see the EXIF data, which is why I am guessing. (The site was too slow).

May I suggest that you test at other distances and focal lengths as well. Make certain that your camera back is absolutely parallel to the target. Make sure that the target is absolutely flat. Glue it to a piece of plywood if you need to. use a tripod and turn off shake reduction. Take the same image at several apertures across the range. Use the 2 sec self timer (or better still 3 sec with the remote if you have it) to make sure that only the lens is affecting the image. use ISO 100.

Once you have finished pixel peeping, go out and take some pictures of real things with the lens. If CA and distortion bother you, go to DxO labs site and download a test run of the software. It costs about $100, but will turn that 16-50 into a perfect lens. It is absolutely unbelievable what it can do. Here is an example of what DxO Standard can do with an image from the 16-50 on my K10D. I paid $900 for the lens or $1,000 with DxO. You can do better

IMGP0801 Original Jpeg on Flickr - Photo Sharing!
08-01-2008, 10:07 PM   #139
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Yeah, I should have clarified the following:

-I first tested the lens using the focus test chart found at
focustestchart.com
and found that my lens is best when focus adjusted to -1. Not bad, compared to some numbers I've read.

-All shots were taken at ISO 200

-All ahots were taken at 2.8

-All shots were taken with the 2 sec. self timer

-All shots were processed in lightroom, but only for white balance and to turn sharpness all the way down (to avoid confusion from artifical sharpening)

-To the best of my abilities, the back of the camera was parallel to the newspaper, but

-the newspaper was nowhere near as flat as I'd have liked.

I won't get around to another test for a few days, but I'll post it when I do.

08-06-2008, 11:05 PM   #140
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All I can say is that the serial numbers are a useless guide to knowing whether a DA*16-50 is good or bad one as it would appear that there is no rhyme or reason as to which is a good or a bad, judging by the respondents.

For what it's worth, mine appears to be a good copy and has a serial number of 9012938.
08-08-2008, 10:43 PM   #141
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Just picked up 9013884 from Henry's in Canada.

Seems to focus well and take a nice shot, but the zoom ring sticks often around the 28mm point. Sometimes it's smooth turning the focus ring (not nearly as smooth as the 50-135mm though) and other times it sticks so much it forces me to adjust my grip and torque on it.

Not sure if that qualifies as bad or good, but if it continues the lens is going back under the exchange/return period. A lens of this price should work as advertised but I'll give it a chance to work in as I'm sure it has sat for a long time on the shelf.

Just a FYI, the display model of the DA* 16-50mm in my local Henry's tried in vain to search for a focus but couldn't achieve focus lock on neither a K10D or a K20D.


**EDIT** - after a couple weeks using the 16-50 I'm pretty sure it's a keeper. Nice picture quality, I'm very happy with the results. at 28mm the top right corner is noticeably softer than the other three corners at f2.8 and f4 but it hasn't bothered me in real life situations yet, in fact I wouldn't have noticed if I didn't do the brick wall test. This lens is leaps and bounds better than the Tamron 17-50mm F2.8 I had tried before it (and so it should be for the $$).

The "stick" in the zoom ring is still there going up slowly from 16mm toward 50mm, having resistance around 28mm but I've become used to it and it seems to be working in a bit too. The resistance in the zoom ring isn't there when moving down toward a wider angle.

The lens is a keeper and I wouldn't hesitate to recommend it to anyone.

Last edited by LSR; 08-28-2008 at 02:04 PM.
08-09-2008, 05:57 AM   #142
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I'm renting one from CLR at the moment and see the same "sticky" point on this one around 28mm. It's actually smooth up to about 26mm, top resistance at 28mm to 50mm.

It's not impossible to spin, just much harder to do so between 28-50 than 16-26. You don't notice it unless you're trying to zoom it slowly.


Per other posts, it seems to be related to added resistance at the point where the second barrel begins to extend out.

Last edited by George Lama; 08-09-2008 at 06:42 AM.
08-09-2008, 11:40 AM   #143
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Purchased DA* 16-50 f/2.8 from Amazon.COM.

Absolutely sharp on the left, very nice, right out to the edges. But about 1/3rd into the right, resolution massively drops off and goes utterly soft.
It's far, far worse than my DA 16-45 f/4 on the right. Horrendously so.

08-09-2008, 01:13 PM   #144
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Hi bj,
Sorry if you got a bad one. When you test make sure that the plane of sensor is as close to parallel to a paper as possible: makes a lot of difference, as I found out.
Good luck
08-09-2008, 02:14 PM   #145
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QuoteOriginally posted by sinus007 Quote
Hi bj,
Sorry if you got a bad one. When you test make sure that the plane of sensor is as close to parallel to a paper as possible: makes a lot of difference, as I found out.
Good luck
Nope, it's not just the plane and some bokeh, it's the lens. I did some more tests. It's the lens.

Find out it's very,very easy to get Amazon to cross-ship -- all automated. Hopefully my second one will be much better.

BTW, no zoom ring issues or anything of the sort. Seems outstanding other than the optical issue.

Last edited by bjsmith; 08-09-2008 at 03:07 PM.
08-10-2008, 08:57 AM   #146
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I bought mine earlier this year from Beach Camera I have no complaints with it. S/N 9020346. This one is of my sister and her grandson taken two weeks ago at 34mm 2.8 1/60 ISO400
Attached Images
 
08-10-2008, 11:44 AM   #147
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I bought all my prior Pentax equipment from Beach Camera. I just went for the price in the Amazon deal, and at 24 months no interest. They are cross-shipping my unit. We'll see if #2 is better.

The K20D and DA* 50-135 f/2.8 were outstanding though.
08-12-2008, 09:43 PM   #148
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Just returned another bad copy of a DA* 16-50.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/34507-my-da-16...hapter-ii.html

The problems were visible at all focal lengths and all apertures, on every day pictures, even at infinity focus. Sorry but I got frustrated and sent the lens back before I had a chance to write down the serial#.
08-12-2008, 11:39 PM   #149
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Hi all,

Just put together a K20d and DA* 16-50 and am concerned about all the buzz about the defective rate on these lenses. I got mine from Amazon just a few days ago and starts with a 9029... How do I go abouts figuring out if my lens is a bunk one or a good one?

(I did some searches here but could not find the answer).

Thanks,
Vic
08-13-2008, 02:06 AM   #150
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QuoteOriginally posted by solarisdreams Quote
Hi all,

Just put together a K20d and DA* 16-50 and am concerned about all the buzz about the defective rate on these lenses. I got mine from Amazon just a few days ago and starts with a 9029... How do I go abouts figuring out if my lens is a bunk one or a good one?

(I did some searches here but could not find the answer).

Thanks,
Vic
Take some pictures and compare the edge sharpness to the center. Test at different apertures and focal lengths. If one edge is sharper than the other it is decentered (Bad). If the edges are all very "soft" compared to the center, again it is bad. My first copy of the lens had the first problem, my second had the second problem. Who knows what the third one will have... Often brick walls are used for this test since you have a uniform surface that you can easily discern the problem. My lens defects were so bad, I could see the problems without a brick wall. I have 2 other threads on this, in this forum.
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