Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-29-2007, 09:28 AM   #1
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
DA* 16-50 First Impressions

I just got the lens yesterday and been playing around with it since, haven't gone on a shoot with it yet so I can't post anything I would normally post but if you want to you can see full size Jpeg test shots here: Zenfolio | Sinan Tarlan | Lens Tests I also compared it to the DA21, FA31 & FA50 shot from a tripod with mirror-lock up with Center Weighed Average metering in Av mode (no other settings or EV comp applied) and converted from RAW with USM at 80% and 0.3 pixel radius saved as quality 10 Jpeg in CS2. Put cursor over photo and click download original if you want to pixel peep the full-size Jpeg's. Remember these are simply test shots - I will post some real sets with real images when I get the chance to shoot - a little busy with certain things the last few days.


Build
-----

Very Good, the zoom ring is actually easier to operate than it looks in the pics. It becomes stiffer as you get close to 28mm or so (when the second part of the barrel starts extends). The lens definetely has a substantial feel to it. Nice big focus ring, can see the weather sealing throughout. SDM is nice and quiet as expected - quite fast too, speedwise I would say it is similar to my DA21 Ltd which is also very fast (but not quiet obviously). Lens cap is nice center pinch type. Hood is decent too with a slot that comes out for easy access to filters. Overall I would say build is as good as it gets for a plastic shelled zoom (the barrel inside may have metal not sure and the plastic itself feels very good quality anyways). Obviously I don't think the lens feels as nice as the Ltd's but overall very good for a zoom IMO. No wobble whatsoever and really the metal thing is more just a matter of feel, as far as actual build quality and robustness it certainly looks and feels up to the task.

IQ
----

Very good - espcially considering the range. My 16-50 is sharp from wide-open (and very very sharp at f/4 and f/5.6), has nice bokeh at f/2.8 @ 50mm. Sharpness is also pretty consistent - at wide-open it still good towards the edges and decent/good at the extreme edges and stopped down by 1 EV it is excellent all acrross the frame. Impressive sharpness from my 16-50 I feel - looks like it will rival the DA21 for sharpness based on quick first impressions. The FA31 and FA50 are sharper at the edges though (but center sharpness is closer than I expected). Contrast is very good, slight vignetting at wide-open at 16mm but not as bad as I was expecting, slight barrel distortion - not a huge deal at all either and given the range- unaviodable by design obviously. It can suffer from CA/Purple Fringing at f/2.8 in extreme contrast but not that bad and stopped down by 1EV it gets better. Bokeh is nice for a zoom and so are the macro capabilties at 50mm wide-open. Overall IQ is very good - very impressed with my copy.

So overall I am very impressed and happy with the performance - definetely a truly versatile all-arounder.

I do find it interesting that there is quite a bit of difference at the exposures when moving from f/2.8 to a smaller aperture with the DA*. It does seem to underexpose more compared to the other lenses past f/2.8 for some reason. I read this somewhere else too regarding this lens and I can see the difference in exposure in the test shots above when comparing the f/2.8's to the f/4's.

08-29-2007, 10:13 AM   #2
Inactive Account




Join Date: Dec 2006
Location: Washington, D.C., USA
Photos: Gallery
Posts: 417
Thanks for posting these pictures. It looks like you got a great copy. Please post more photos as you take them. I am hoping to read more positive reviews like yours to offset my negative experience with the lens and convince myself to try another copy. Many thanks and enjoy the lens!
08-29-2007, 10:36 AM   #3
Veteran Member
FotoPete's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 1,710
QuoteOriginally posted by Wethphotography Quote
Thanks for posting these pictures. It looks like you got a great copy. Please post more photos as you take them. I am hoping to read more positive reviews like yours to offset my negative experience with the lens and convince myself to try another copy. Many thanks and enjoy the lens!
Omg are you STILL hanging on to that decentered DA*16-50?? Get it replaced already! The longer you wait, the more grouchy salespeople get.
08-29-2007, 11:14 AM   #4
sft
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
Original Poster
I have removed the FA50, f/4 and f/5.6 shots since my FA50 front focuses unfortunately and I only manually focused the f/2.8 shot which is sharp. The DA* displays good performance IMO but obviously it cannot quite match prime quality accross the frame (especially at the larger apertures) though it is quite close in the center of the frame.

08-29-2007, 01:51 PM   #5
Inactive Account




Join Date: Dec 2006
Location: Washington, D.C., USA
Photos: Gallery
Posts: 417
QuoteOriginally posted by FotoPete Quote
Omg are you STILL hanging on to that decentered DA*16-50?? Get it replaced already! The longer you wait, the more grouchy salespeople get.
It is long gone! I returned it. I choose not to replace it until I was sure there were good copies out there....
08-29-2007, 02:06 PM   #6
sft
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
Original Poster
Erl - how would you say my copy is compared to your one that you returned? Did you take a look at the full-size photos on the webpage? I feel that I got a good/normal copy but obviously the lens cannot match the primes - what exactly was worse about yours that made you return it?
08-29-2007, 03:37 PM   #7
Veteran Member
jeffkrol's Avatar

Join Date: Sep 2006
Location: Wisconsin USA
Photos: Gallery
Posts: 8,435
QuoteOriginally posted by sft Quote
Erl - how would you say my copy is compared to your one that you returned? Did you take a look at the full-size photos on the webpage? I feel that I got a good/normal copy but obviously the lens cannot match the primes - what exactly was worse about yours that made you return it?
Here are his samples...
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/10639-da-16-50...n-28-75-a.html
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/10639-da-16-50...28-75-a-2.html
08-30-2007, 01:36 AM   #8
sft
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
Original Poster
Ah I see, so it looks like his copy had some serious focusing issues (or a terribly defective lens if it did focus correctly). I guess if manually focusing gave sharp results then it is a problem with the focusing - either way it is not acceptable to have such a performing lens no doubt.

08-30-2007, 07:41 AM   #9
Pentaxian
rvannatta's Avatar

Join Date: Aug 2007
Location: Apiary, Oregon
Photos: Gallery
Posts: 1,176
QuoteOriginally posted by Wethphotography Quote
Thanks for posting these pictures. It looks like you got a great copy. Please post more photos as you take them. I am hoping to read more positive reviews like yours to offset my negative experience with the lens and convince myself to try another copy. Many thanks and enjoy the lens!
Mine has been hanging around for a week now. I really like the SDM for being fast and quiet. I'm not ready to judge its optical usefulness until I get
some experience with it. Somehow the first picture ever taken with a new lens is often not the best one ever taken....
08-30-2007, 08:24 AM   #10
sft
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
Original Poster
Zenfolio | Sinan Tarlan | Sharpness, CA, Color, Contrast, Vignetting, Distortion, Focusing Accuracy Tests

Added another test series for sharpness, CA, etc.
Also added a section to see vignetting at 16mm and barrel distortion.


What is troubling is that the AF mechanism is hit or miss. When it locks focus it is sharp. But it sometimes completely misses focus and backfocuses which is troubling. It is more often right than it is not but I am slightly dissapointed that the AF can be so off and one has to check to make sure it is OK. Batteries do not affect the outcome as I tested with 2 charges sets of batteries - the other lenses focus fine (except FA50 can also be problematic on occasion when the battery is low, the DA* is regardless of battery though).

My thoughts so far as follows:

Sharpness is good, CA is well controlled (except at f/2.8). Distortion is evident at 16mm but not that bad. Vignetting is quite heavy at 16mm at f/2.8, much less so at f/4 and negiligble at f/5.6. At other focal lenghts it becomes negligible by f/4. The lens tends to underexpose at f/4 or smaller apertures. Ie. at f/2.8 it meters 1/2000 whereas at f/4 it will meter 1/1250 whenit should meter 1/1000. So it seems to require +1/3 EV when at f/4 or beyond. The focusing is also so-so on my copy. It misses focus on occasion (more often than I would like). All in all - I have mixed feelings. It can render nice (bokeh, sharpness, etc.) but it seems to be a problematic lens unfortunately. I read another post about the DA* underexposing by 1/3 stop or so and this was compared to the DA16-45 and I read another post about it missing focus completely (all the time) - at least mine can focus correctly. My biggest problem is the focusing innacuracy - the underexposure I can deal with and the other aspects like CA + Vignetting, etc. are a given of any f/2.8 WA zoom lens. I will test the focusing out more in different scenarios to see if the problem is consistent (hopefully not!!).
08-30-2007, 09:14 AM   #11
Veteran Member
FotoPete's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 1,710
QuoteOriginally posted by Wethphotography Quote
It is long gone! I returned it. I choose not to replace it until I was sure there were good copies out there....
Haha I thought you were still hanging on to that one. WEll now that you've returned it, perhaps there's time for the Tamrom SP 17-50mm f2.8 Di XR to enter the equation. (w/ ~$400 left over)
08-30-2007, 02:14 PM   #12
sft
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
Original Poster
Seems my AF is defective

Yep, it is for certain unfortunately. Out of 57 shots I took to test focus I would say about 20 are in focus. The rest are backfocused (and some extremely backfocused) and I have uploaded some of the bad AF shots here Zenfolio | Sinan Tarlan | Focusing Accuracy, Vignetting, Distortion Test of DA* 16-50 (New) - see shots 11 and further to see the new samples of the AF problem.

I will try to get the lens repaired by a Pentax Service Center to get the AF problem fixed. Otherwise - optically the lens is quite excellent and the sharpness tests (and all other tests) can still be used to see the performance as I made sure those are focused properly and there is nothing wrong optically with the lens, just the AF. Bummed about that.
08-30-2007, 09:34 PM   #13
Pentaxian
rvannatta's Avatar

Join Date: Aug 2007
Location: Apiary, Oregon
Photos: Gallery
Posts: 1,176
QuoteOriginally posted by sft Quote
Yep, it is for certain unfortunately. Out of 57 shots I took to test focus I would say about 20 are in focus. The rest are backfocused (and some extremely backfocused) and I have uploaded some of the bad AF shots here Zenfolio | Sinan Tarlan | Focusing Accuracy, Vignetting, Distortion Test of DA* 16-50 (New) - see shots 11 and further to see the new samples of the AF problem.

I will try to get the lens repaired by a Pentax Service Center to get the AF problem fixed. Otherwise - optically the lens is quite excellent and the sharpness tests (and all other tests) can still be used to see the performance as I made sure those are focused properly and there is nothing wrong optically with the lens, just the AF. Bummed about that.
I'm not completely convinced the issue is a lens issue or the AF.
Here is a photo that I took this morning. I started out with the lens
in the 16mm position poked the shutter button half way so I could see what I was doing, and cranked the lens out to 50 mm and took the picture.



This picture was taken in the green mode with auto ISO enabled.
It was taken at F2/8, 1/60 sec at iso 400 at 50 mm focal length. the close focus is excellent--- as with the light in the lower left corner as are the highlighted limbs on the left. the 'hole' in the middle of the photo is out of focus.

You can find the full sized jpg at "Http://www.vannatta.com/misc/pentax1650.jpg"

I then moved and reaimed the camera slightly and the focus readjusted and picked up some trees about a 1/3d of the way down the hole which were in focus. The light in the lower left was out of focus as was the center of the 'hole'.

INterestingly at the 3x5 snapshot size in this message the focus failure
in the center of the photo is not obvious.

I think what you are looking at is a depth of field limitation inherent in a fast lens. Since I can position the camera so both the close foreground and the far background are out of focus, I find it hard to blame this on the AF.

Rather I'm inclined to cast the blame on a combination of 2 things:
a) A very fast lens which therefore has inherently short depth of field and
b) a high resolution recording ability that lets us actually see the soft focus.

I've noticed this issue generally with the K10 using other lenses as well.
Depth of field issues are readily apparent in many of my photos and are far more obvious with the K10 than any camera that I have ever owned.

I don't blame it on the camera, but rather on the technical ability of the camera to record the inherent limitations of the optics.

One feature that I have found that makes a major difference in the focus
results is the setting of the 'AF.C/AF.S' control. If you use this camera in
the AF.S (single locked mode) you can produce some really disasterous results by recomposing after you activate the light meter and lock the focus.

One of my habits is to 'recompose' the photo by cranking the zoom in and
out after naturally I've activated the focus. As far as this lens zooms
it is very easy to lock the focus down, and then zoom into an area that was out of focus effectively producing a photo that is completely out of focus.

Better technique, I suppose would be to start with the lens at max extension and back down to a wider angle. The rules of physics say do it that way, but it is more logical to first view the whole field and then if appropriate zoom in on what you want.

Likewise since the SDM lens makes no noise when focusing, you don't have the noise to help remind you to force the camera to refocus if you recompose.

You don't mention whether you have used the factory default AF.S single shot focus mode or the AF.C continuous mode, but my take is that a zoom
lens should ALWAYS be used in the AF.C mode, except for special effects or unless you can train yourself to zoom the lens all the way out and point it at what you want in focus, and then activate the AF, and then turn the lens wider to include what ever else is desired.
08-31-2007, 02:17 AM   #14
sft
Senior Member
sft's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 173
Original Poster
Thanks for the reply mate but let me assure you that I am a technically advanced user and that I have tried everything there is to try - AFS, AFC, Tripid & Mirror Lock Up, Manual Focus Bracketing, etc etc. I can guarantee that the issue here is not a user one but the lens is simply backfocusing almost eveytime. I have plenty of other fast & faster lenses (even f/1.4 and f/1.8) so I know how to use my equipment and judge performance.

I will get in contact with Pentax to send the lens for warranty repair, otherwise I have also judged the lens optically and it is a very good performer - it just has a definete backfocus problem but thanks anyways for your long reply mate - wish I could say it was user error but unfortunately it isn't.
08-31-2007, 06:53 AM   #15
Inactive Account




Join Date: Dec 2006
Location: Washington, D.C., USA
Photos: Gallery
Posts: 417
Sinan,
I am sorry to learn of your experience. Believe me when I tell you that I have experienced your frustration and it is not fun. Please share with us your experiences with the lens when it comes back and what Pentax had to say about the problem. Best wishes.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
barrel, center, da21, f/2.8, k-mount, lens, pentax lens, post, quality, sharpness, slr lens, test, wide-open
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
My K-5 First Impressions deadwolfbones Pentax K-5 53 10-29-2010 07:31 PM
K-x first impressions ilya80 Pentax DSLR Discussion 7 11-04-2009 11:00 AM
DA* first impressions Ishpuini Pentax SLR Lens Discussion 7 10-02-2009 01:48 PM
Your impressions Zeno Photo Critique 14 06-18-2009 05:52 PM
Impressions on the K-m paolojackson Pentax DSLR Discussion 4 12-03-2008 04:41 PM



All times are GMT -7. The time now is 07:13 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top