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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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04-07-2008, 04:51 PM   #646
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Red,

If the focus chart is truly parallel to the image sensor, then you indeed have a centering defect and should exchange the lens. You must be certain, however, that the chart is perfectly parallel to the sensor.

Ted

04-08-2008, 08:17 AM   #647
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Thank you all for the comments. I should provide more evidence for this lens, but I cannot, since most of the test pics had been deleted immediately after checking on camera.
In fact, I've returned this lens and ordered a K20D... WOW! Maybe I'll come back someday, to DA*16-50 II,
04-09-2008, 05:47 AM   #648
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I don't know if it's a good one but it's sure much better than mine -- mine was totally OOF when wide open @ 16mm and frequently i can't push the shutter button down when in AFS mode. i got it before departure for a long journey in east asia and during the trip i had to shoot @ f5.6 or slower...
04-09-2008, 07:32 AM   #649
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I've tested two good copies, none of them displace such severe vignetting. Outdoor shooting would be better.

04-09-2008, 07:42 AM   #650
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A monitor makes for a bad test subject.

If you'll notice, monitors are brightest when viewed from head-on. If you go to the side they get darker. At 16mm, the angle that light must take to get from the screen to the lens is too high for good viewing, so the light cuts off. You can try it with your own eyes if you want – move your head side to side and the screen will get bright and dark.
04-09-2008, 10:50 AM   #651
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I will test the lens and post out door test shots later. so far, it looks like a good copy.
04-09-2008, 07:00 PM   #652
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Your copy is a great copy.

There is too much emphasis on corner sharpness where it rarely matters unless you are selling large prints to fussy customers.

Vignetting is normal at this aperture and it can add impact to a protrait shot with that effect.

It is good to know your own equipment with testing but do not go overboard. This zoom's weakness is not really a big deal provided it does not have de-centering issue or severe back focusig at 1 meter distance.

Otherwise, use it as a kit zoom. Once you used it in the field for at least a few thousand shots, you will have your conclusion.
04-09-2008, 07:10 PM   #653
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Keep in mind that the 16-50mm is not macro, the minimum focus distance is 1 foot.

04-09-2008, 07:45 PM   #654
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don't use a monitor or crt for sharpness tests - they themsleves have greater center-to-edge sharpness fall-off than a lens, especially considering the angle-of-view and light fall-off.
04-14-2008, 05:44 AM   #655
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Hyperfocal setting on DA*16-50mm lens

Hello to all,
I'm new to the world of DSLRs so this might be a dumb question!
For years I used hyperfocal settings and it now seems that on the K10D with the DA 16-50mm, one has to use the optical/digital preview and/or program line set to DEPTH. Or is there a sneaky way in this?
Thanks.
Richard
04-14-2008, 06:56 AM   #656
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It works the same way as your old SLR. Just calculate hyperfocal distance for the f stop and focal length you want to use and use it accordignly. It'll work...
good luck
04-14-2008, 07:09 AM   #657
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Ooh. Write to Pentax and recommend they implement this idea

https://www.pentaxforums.com/forums/pentax-dslr-discussion/19781-idea-future-...ocal-mode.html

in a firmware update.

An impressive number of little ideas seem to have gotten into the K20D, so I think there's real reason to believe that if we get enough people asking for it, it'll really happen.
04-14-2008, 08:21 AM   #658
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Check out the Online Depth of Field Calculator

It probably wouldn't take long to generate a chart for 3 or 4 focal lengths at a few apertures. But Matt's firmware update idea would be awesome!
04-14-2008, 10:25 AM   #659
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QuoteOriginally posted by Groundloop Quote
Check out the Online Depth of Field Calculator

It probably wouldn't take long to generate a chart for 3 or 4 focal lengths at a few apertures. But Matt's firmware update idea would be awesome!
SOB!!! That chart would of been so helpfull while at the Grand Canyon, there were a number of shots that I would of loved to have the Canyon in focus as well as the foreground. Bookmarked now.
04-21-2008, 01:31 AM   #660
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Pentax 16-50mm f2.8 lens 9019*

Hi,

I decided to risk it and spend money on this lens.

What is the best way to test my lens for de-centering problem and what other issues are the common problems for this lens?

Thanks.
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