Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-14-2013, 09:24 AM   #16
ogl
Pentaxian
ogl's Avatar

Join Date: Dec 2007
Location: Siberia
Photos: Gallery | Albums
Posts: 7,246
It seems to me your 20-40 has AF problems...

12-14-2013, 10:36 AM   #17
Senior Member




Join Date: May 2012
Location: San Jose, CA
Posts: 111
Original Poster
QuoteOriginally posted by Andr3w Quote
How is the 20-40 in the corners? I am particularly interested in 21 vs. 20-40 at f/8 in the corners.
DA21 f/8
http://photos.smugmug.com/Other/Pentax-Lenses/i-LvNGTvf/0/O/IMGP2672.jpg

DA 20-40 21mm f/8
http://photos.smugmug.com/Other/Pentax-Lenses/i-tbHnHcD/0/O/IMGP2814.jpg
12-14-2013, 11:30 AM   #18
Pentaxian
Driline's Avatar

Join Date: Dec 2012
Location: IOWA Where the Tall Corn Grows
Photos: Gallery
Posts: 2,973
Hmmmm... It looks like the lighting changed a bit between lenses. I can also see the sandal fell off the stoop between shots too. Overall the DA 20-40 looks a bit brighter and less muddy but again that could be because of the difference in lighting? Not sure...
12-14-2013, 01:15 PM   #19
Veteran Member
krebsy75's Avatar

Join Date: Jun 2010
Location: Chester County, Pa.
Posts: 804
I appreciate the effort but "testing" lenses should be done where lighting can be controlled. CDAF should also be used.

12-14-2013, 02:26 PM   #20
Senior Member




Join Date: May 2012
Location: San Jose, CA
Posts: 111
Original Poster
Cdaf

QuoteOriginally posted by sanjeevdas Quote
I don't actually shoot using live view much, which is why I didn't do it. I do understand what you mean though. I'll try a CDAF/PDAF test to see if this is a focus issue.
About the beer, I actually intend to enjoy them afterwards as I browse through the images
DA 20-40 20mm f/4
PDAF


DA 20-40 20mm f/4
CDAF


DA21 f/4
PDAF
12-14-2013, 02:29 PM   #21
Pentaxian
Driline's Avatar

Join Date: Dec 2012
Location: IOWA Where the Tall Corn Grows
Photos: Gallery
Posts: 2,973
QuoteOriginally posted by sanjeevdas Quote
DA 20-40 20mm f/4
PDAF


DA 20-40 20mm f/4
CDAF


DA21 f/4
PDAF
DA 21 is noticeably sharper.... not as muted, and seems to have better contrast in the pictures you provided.
12-14-2013, 03:50 PM   #22
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,406
Interesting. If you take out the CA on both then the DA 20-40 is as good, if not better, than the DA21 over the whole frame. What is it like wide open ?

Nice Moire at the bottom of the door blind
12-14-2013, 04:08 PM   #23
Senior Member




Join Date: May 2012
Location: San Jose, CA
Posts: 111
Original Poster
DA 20-40 wide open

QuoteOriginally posted by kh1234567890 Quote
Interesting. If you take out the CA on both then the DA 20-40 is as good, if not better, than the DA21 over the whole frame. What is it like wide open ?

Nice Moire at the bottom of the door blind
Ha! I never noticed that!

From today:
DA 21 f/3.2 PDAF
http://photos.smugmug.com/Other/DA21-vs-DA-20-40/i-w2FqPKj/0/O/IMGP3135.jpg

DA 20-40 20mm f/2.8 CDAF
http://photos.smugmug.com/Other/DA21-vs-DA-20-40/i-39s47px/0/O/IMGP3124.jpg

12-14-2013, 04:32 PM   #24
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,406
QuoteOriginally posted by sanjeevdas Quote
The DA 20-40 is just a touch decentered (top right corner vs top left) but is doing well. I could live with that. It is interesting how much difference that one mm of focal length makes.

What is the AF like ? The DA21 is really fast and just right for those 'from the hip' street photos. Tempting ...
12-14-2013, 04:40 PM   #25
Senior Member




Join Date: May 2012
Location: San Jose, CA
Posts: 111
Original Poster
QuoteOriginally posted by kh1234567890 Quote
The DA 20-40 is just a touch decentered (top right corner vs top left) but is doing well. I could live with that. It is interesting how much difference that one mm of focal length makes.

What is the AF like ? The DA21 is really fast and just right for those 'from the hip' street photos. Tempting ...
AF on the DA 20-40 is very fast. I didn't notice any difference with the other limiteds. The lens is much larger than the DA21 though (although very light). For 'from the hip' shooting the DA21 would probably be the best. Although to be honest, I don't like my DA21 that much (compared to the other limiteds). For off the hip shooting, I'd far prefer the DA15.
12-14-2013, 05:38 PM   #26
Forum Member




Join Date: Jan 2012
Posts: 87
I just got my new 20-40 Ltd, and did some initial tests using my K-01 at 20mm against my 20/2.8 FA (an awesome classic full frame lens), and against my new 35/2.8 Macro Ltd.

My 20 FA is better at 2.8. In some cases, MUCH better. My lens seems decentered, with center/center right weaker than the left side. For a $900 lens, I expect better. At 4.0, the two become closer and by 8.0, the two lenses are basically equal. FYI, my 20 FA is a superb lens and my copy is perfectly centered, made in Japan. I need to perform more testing, but my main issue with the 20-40 right now is weakness wide open at 20mm. I'd like to know if others have this issue also. Note: Does the 20-40 Ltd really start at 20? My 20/2.8 FA is definitely WIDER than my 20-40 Ltd at 20mm. Can others check this out?

Shooting the 20-40 against the DA 35 Ltd Macro, things were better for this new zoom. The 20-40 (for landscapes, not macro) was equal or just slightly sharper. Kind of a surprise.

SDM focusing did not seem faster at all on the K-01, versus primes with screw drives. Of course, the macro has more distance to hunt.

I need more time to test at 20/2.8 and figure out the degree of decentering. I was a little surprised at how large the 20-40 is....basically similar to my 20-35/4 FA. My new Sigma 18-250 Macro version is not much bigger, for example. So far I have mixed feelings about this lens. It does not have the metal feel of the other limiteds and just doesn't seem as special. Oh, and the color is too blue for sure. The colors from my 20/2.8 FA are much more accurate. I may also consider the Sigma 18-35 when it comes out.

Last edited by rdj92807; 12-14-2013 at 05:57 PM.
12-15-2013, 06:23 AM   #27
ogl
Pentaxian
ogl's Avatar

Join Date: Dec 2007
Location: Siberia
Photos: Gallery | Albums
Posts: 7,246
Its' strange to buy the lens with decentering defects for such money. I was ready to order DA20-40 yesterday, but changed my mind. I will wait for any serious tests.
I worry about QC of this lens.
12-15-2013, 07:08 AM   #28
Veteran Member
krebsy75's Avatar

Join Date: Jun 2010
Location: Chester County, Pa.
Posts: 804
Purchasing anything Pentax related right out of the chute may be a risky endeavor. We bought an 18-135mm when it first came out and it was horrid - worse optically than the 18-55mm we had at the time.

Decentering issues should disappear once the lens is stopped down one full stop. If not, it's definitely defective.
12-15-2013, 07:10 AM   #29
Veteran Member
krebsy75's Avatar

Join Date: Jun 2010
Location: Chester County, Pa.
Posts: 804
QuoteOriginally posted by ogl Quote
Its' strange to buy the lens with decentering defects for such money. I was ready to order DA20-40 yesterday, but changed my mind. I will wait for any serious tests.
I worry about QC of this lens.

As I understand it consumer lenses aren't calibrated for perfect centering wide open.
12-15-2013, 07:17 AM   #30
Veteran Member
krebsy75's Avatar

Join Date: Jun 2010
Location: Chester County, Pa.
Posts: 804
QuoteOriginally posted by rdj92807 Quote
I may also consider the Sigma 18-35 when it comes out.

The Sig 18-35 and 20-40 aren't really comparable in my opinion. The Sigma user wants full-frame depth of field in a zoom for crop. The Pentax user wants something in a more practical package
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!
da, da*, da21, fa31, fa43, k-mount, limiteds, pentax lens, pictures, slr lens, w/ comparison
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
DA limited 20-40 f/2.8-4 mounted images rlatjsrud Pentax News and Rumors 107 11-04-2014 02:34 PM
The DA limited is 20-40? and WR?! LFLee Pentax News and Rumors 1331 02-13-2014 10:55 PM
DA 20-40 Limited zoom availability lytrytyr Pentax SLR Lens Discussion 20 12-05-2013 03:21 PM
DA limited 20-40 f/2.8-4 rlatjsrud Pentax SLR Lens Discussion 3 11-02-2013 11:04 AM
For Sale - Sold: Pentax DA 40 F2.8 limited w/ Nisi XS uv (shipping included / Reduced) hermitlun Sold Items 8 08-09-2012 08:36 PM



All times are GMT -7. The time now is 08:53 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