Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-21-2017, 02:54 PM   #1
Pentaxian
mgvh's Avatar

Join Date: Sep 2010
Location: MD
Photos: Gallery | Albums
Posts: 910
DA 16-85: How much decentering is too much?

I have the DA 18-135. It's been a fine lens. I've lived with the edge softness (which is not due to decentering). For the shooting I do, I wanted something a little wider and a little better quality. The DA 16-85 is the obvious choice. I can't afford a new one, but I found a used one on Amazon. Externally it's perfect, and the glass is spotless.

I'm putting it through its paces, since I do have a 30-day return policy. First impressions:
  • I really like the extra 16mm at the wide end.
  • It is a higher quality lens than the 18-135, and it isn't that much bigger.
  • The center is definitely sharper, and the edges are much better for the most part, but...
The lens clearly has a little bit of a decentering issue.
At the 16mm end, the effect can be reduced by closing down. Here is a shot at f7.1. The cedar trees were on the left and right edges of the shot. You should be able to see that the right side is softer.



The decentering is a bit less noticeable as I zoom. Not much to speak of in the 35-60mm range. At 85mm, the softness has moved to the left side, though it is not as pronounced.

For comparison, I took the same shot with the 18-135mm at 18mm and moved back just a bit to get the same field of view. You should be able to see that the 16-85 on the left is a bit softer than the 18-135 on the right, both showing the same right side of the pic. (The 16-85 is superior to the 18-135 everywhere else in the picture.)



Now I realize there really isn't a perfect lens. There will always be some edge softness. The softness varies with aperture and with zoom. There is always some compromise that is made.

I'm trying to decide whether to return/exchange the lens. I got it for a good price, and, as noted, externally it's in perfect condition. There is also no guarantee that I will get a better lens. (Tibbets went through 5 copies of the 16-85 to get one he was satisfied with!)

So, how much decentering is too much? Is it just a matter of deciding what one can live with, balancing out the lens quality and price, etc.? I'm inclined to keep the lens, since I don't know about getting a better one at the same price, but I'd appreciate hearing how others decide whether to return/exchange a lens or not. Thanks!

05-21-2017, 03:57 PM   #2
Loyal Site Supporter
Loyal Site Supporter




Join Date: Feb 2010
Location: Maryland
Posts: 393
The decentering you show is relatively minor and may not effect most shots. Only you can decide how much softness is too much. Keep in mind that many landscape shots will be stopped down and the softness will be much less pronounced. Looks like you got a pretty good lens. I tested my 16-85 upon purchase last year and detected some decentering. You also might have a look here (the forum staff can remove if this is a breach :-):

Lens Rentals | Blog

Interesting read and fits my experiences:-)
05-21-2017, 04:08 PM   #3
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 9,520
I have seen worse. Some would say that any amount of de-centering is bad - however this is not a particularity realistic ideal, especially in zoom lenses which are inherently more complex, and have more moving parts than most prime lenses. In zoom lenses there are more points where optical misalignment can occur there is a correlation towards a higher defect rate among lenses with wider FOV. For most purposes, this lens will be OK.
05-21-2017, 04:18 PM   #4
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 11,183
QuoteOriginally posted by mgvh Quote
So, how much decentering is too much? Is it just a matter of deciding what one can live with, balancing out the lens quality and price, etc.? I'm inclined to keep the lens, since I don't know about getting a better one at the same price, but I'd appreciate hearing how others decide whether to return/exchange a lens or not. Thanks!
Yeah, comes down to your needs, and how much of a hassle you are willing to go through. I had my Samyang 14mm replaced because it was decentered. But the shop was kind of annoying about it. The second copy still shows some decentering, but I accepted it. Its good enough and going through the shop again would not be worth it. Especially considering the third copy might be just as bad or worse.

So, while the 16-85mm is not as famous as that Samyang for decentering, you still might not get a perfect copy. I would say if you shoot a lot of things at the wide angle and its the type of photos where you need sharpness across the frame, then go and get it replaced. If you are mostly a telephoto shooter or your UWA photos focus on other things, like colors and contrasts... well, you know.
You can still take it to the shop and just ask their opinion, to see how they respond. If they let you test the second copy before replacement, on the spot, then you don't have much to fear, manual focus with focus peaking

The stuff I see in those crops is not too terrible. Do one more test near the minimum focusing distance to judge the CA and DoF better. Wide open aperture, 2 sec timer

05-21-2017, 06:18 PM   #5
Loyal Site Supporter
Loyal Site Supporter
Scorpio71GR's Avatar

Join Date: Nov 2014
Location: Michigan
Photos: Gallery | Albums
Posts: 4,404
Owning both the 18-135 and the 16-85 I would have to say I would return it. I say this because the 16-85 is capable of better results. Unless you feel you can live with it. The 16-85 is worth getting a good copy in my opinion. I purchased mine here in the marketplace so I was able to see some shots taken with before I bought it. At 16mm my 16-85 outperforms my DA*16-50 across the entire frame. The 16-50 is superior in the center.

16mm f5.6 on the K3.

05-21-2017, 07:20 PM   #6
Loyal Site Supporter
Loyal Site Supporter




Join Date: May 2016
Location: East Coast
Posts: 1,660
I'd return it. I've had a couple 16-85's go through my hands, and I think they can/should be better than that. Too me, it's visibly blurry, and it would bug me. Others obviously are OK with it, so it does get down to how addicted you are to zooming in, how big you might print it, how sharp does it have to be?
05-21-2017, 07:33 PM   #7
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 12,347
You're entitled to a refund, Mgvh, so you should ask for it.

Lenses cost a lot of money to tolerate not being up to spec.
05-21-2017, 07:40 PM   #8
Pentaxian
mgvh's Avatar

Join Date: Sep 2010
Location: MD
Photos: Gallery | Albums
Posts: 910
Original Poster
Thank you, all. I'm still undecided. I do indeed think the lens could be better, but I'm not sure that I can get a better used one for the $440 I paid for this one.
I guess I'll do more shooting, and see what difference focal length / aperture makes, and whether I can live with the results without being annoyed by the softness.

05-21-2017, 10:19 PM   #9
Pentaxian




Join Date: Jun 2015
Location: Melbourne, Australia
Photos: Albums
Posts: 334
It looks like too much to me. What happens when you capture a great shot and the decentering is to blame for ruining it? It's hard enough to get good shots with a good lens. Not worth $440 for sure. I paid half as much for a Sigma 10-20 f/4-5.6 and it produces better - and make no mistake, there are better lenses on Ebay out there. It's a hassle but why not get one of those?
05-27-2017, 11:37 AM   #10
Pentaxian
mgvh's Avatar

Join Date: Sep 2010
Location: MD
Photos: Gallery | Albums
Posts: 910
Original Poster
I decided to return the lens. If I'm going to pay $440 for a lens, even if that's a fair price for a used one, that softness would always bother me. If it were an issue at the tele end, I might not mind it so much, but I got the lens to shoot at 16mm. If I would have to crop out that right side due to softness (which was softer than my 18-135mm at 18mm), then I might as well just stick w/ the 18-135. I'm thinking I'll try another copy of the 16-85... Thanks again for your advice!
06-06-2017, 02:01 PM - 1 Like   #11
Pentaxian
mgvh's Avatar

Join Date: Sep 2010
Location: MD
Photos: Gallery | Albums
Posts: 910
Original Poster
UPDATE 2017.6.6: I found a used 16-85 at B&H for $440 (same price as first one). This one is MUCH BETTER. Maybe a tad soft on the right side but nothing to complain about. Whereas the first 16-85 (at 18mm) in comparison to my 18-135 had similar sharpness in the center, a bit better on the left, but much worse on the right, this new one is a bit better in the center, and noticeably much better on both edges. I'm glad I returned the first one. (It was from Amazon Warehouse, and the return was free and no-hassle.)
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!
bit, da, flickr, k-mount, lens, pentax lens, price, quality, shot, slr lens, softness, zoom
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Nature Another person with too much money and too much time Murra54 Post Your Photos! 10 02-15-2016 09:14 PM
DA 16-85 vs. DA* 16-50; which is a better travel lens? Newtophotos Pentax SLR Lens Discussion 41 01-08-2016 08:32 AM
DA* 16-50, does this look like decentering to you? elpolodiablo Pentax SLR Lens Discussion 2 09-19-2013 08:50 AM
Possible 16-50 DA* Decentering Gridlinked Pentax SLR Lens Discussion 7 05-05-2009 12:05 AM
When is too much, too much? lbenac Pentax Film SLR Discussion 15 05-03-2009 04:49 PM



All times are GMT -7. The time now is 05:02 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