Question for 16-50mm owners

Tbear · 04-07-2008, 04:51 PM

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

reddream · 04-08-2008, 08:17 AM

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,

safari · 04-09-2008, 05:47 AM

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...

aegisphan · 04-09-2008, 07:32 AM

I've tested two good copies, none of them displace such severe vignetting. Outdoor shooting would be better.

Aegon · 04-09-2008, 07:42 AM

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.

joonee88 · 04-09-2008, 10:50 AM

I will test the lens and post out door test shots later. so far, it looks like a good copy.

roentarre · 04-09-2008, 07:00 PM

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.

thear · 04-09-2008, 07:10 PM

Keep in mind that the 16-50mm is not macro, the minimum focus distance is 1 foot.

Tom M · 04-09-2008, 07:45 PM

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.

Rnovo · 04-14-2008, 05:44 AM

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

axl · 04-14-2008, 06:56 AM

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

mattdm · 04-14-2008, 07:09 AM

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.

Groundloop · 04-14-2008, 08:21 AM

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!

Buddha Jones · 04-14-2008, 10:25 AM

Originally posted by Groundloop

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.

feronovak · 04-21-2008, 01:31 AM

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.

View Poll Results: Is this DA*16-50mm good or bad?
Keep it -- it's good.	23	88.46%
Return it or send it in for repair.	3	11.54%
Voters: 26. You may not vote on this poll

04-14-2008, 05:44 AM	#655
Rnovo Closed Account Join Date: Mar 2008 Location: Halifax, Nova Scotia, Canada Photos: Gallery \| Albums Posts: 415	*Hyperfocal setting on DA16-50mm 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

04-21-2008, 01:31 AM	#660
feronovak Senior Member Join Date: Apr 2007 Location: London, UK Photos: Gallery Posts: 123	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.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Question to K-5 Owners	kevinschoenmakers	Pentax K-5 & K-5 II	3	10-19-2010 06:40 PM
Question for K-X owners.	dimebagdave	Pentax DSLR Discussion	6	04-29-2010 05:17 AM
PZ-1P question(for owners)	LongLiveVelvia	Film SLRs and Compact Film Cameras	3	10-09-2009 10:51 AM
A question for K7 owners	dafiryde	Pentax DSLR Discussion	26	09-05-2009 02:52 AM
Question for FA 28-70/4 owners	Ivan Glisin	Pentax SLR Lens Discussion	8	08-13-2007 01:08 PM

04-07-2008, 04:51 PM	#646
Tbear Senior Member Join Date: Aug 2007 Location: Pittsburgh, PA Photos: Gallery \| Albums Posts: 269	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
reddream New Member Join Date: Apr 2008 Posts: 17	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
safari Inactive Account Join Date: Dec 2007 Location: Honolulu 04-08 / Beijing 08- forever Posts: 48	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
aegisphan Veteran Member Join Date: Nov 2007 Location: New Mexico Posts: 815	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
Aegon Site Supporter Join Date: Jan 2008 Location: Portland, OR Posts: 1,416	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
joonee88 New Member Join Date: Jan 2008 Location: CA Posts: 11	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
roentarre Veteran Member Join Date: Oct 2006 Location: Melbourne, Australia Posts: 11,783	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
thear Forum Member Join Date: Jul 2007 Posts: 83	Keep in mind that the 16-50mm is not macro, the minimum focus distance is 1 foot.

04-09-2008, 07:45 PM	#654
Tom M Veteran Member Join Date: Aug 2007 Location: Lincoln Park, NJ Photos: Gallery Posts: 780	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, 06:56 AM	#656
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	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
mattdm Veteran Member Join Date: Feb 2007 Location: Boston, MA Photos: Gallery Posts: 2,948	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
Groundloop Senior Member Join Date: Aug 2007 Location: Toronto, Canada Photos: Gallery Posts: 236	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
Buddha Jones Veteran Member Join Date: Sep 2006 Location: Charlotte, NC Photos: Gallery Posts: 2,587	Originally posted by Groundloop 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.