Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-08-2011, 12:26 PM   #16
Pentaxian




Join Date: Jul 2010
Location: Oregon
Photos: Albums
Posts: 1,417
QuoteOriginally posted by Ash Quote
Thanks Phil.
The Sunny Coast has a special place in myself & my family's hearts - a beautiful part of the world.

As for the extra width of the Sigma, the extra couple of mm does come in handy at times (you'd be surprised how wide you want to go sometimes) but the main issue with such wide lenses is the amount of perspective distortion that has to be introduced as you can see from the above posted examples. Some of this can be corrected in PP and even your framing can help to minimise its unwanted effects, but it can be problematic, particularly with non central/symmetrical compositions. This is why I have found the DA 12-24 to be the best in this application (if 12mm is wide enough) - it offers great image quality without too much distortion.
The difference in distortion is not so great. According to photozone tests:
Sigma 8-16 has 2.87% at 8mm and 0.501% at 12mm
DA12-24 has 2.11% at 12mm

Both are excellent lenses, better than available primes. The Sigma is wider, the Pentax takes filters.

05-08-2011, 03:02 PM   #17
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 8,939
QuoteOriginally posted by Ash Quote
but the main issue with such wide lenses is the amount of perspective distortion that has to be introduced as you can see from the above posted examples.
But that perspective distortion is the reason why one uses wide angle lenses?!

If you don't want the perspective distortion, just use a normal focal length and step back. Sometimes stepping back is not possible, but that's not the point. The point is that perspective distortion is a feature of wide angle lenses, not a bug. Perspective distortion is unavoidable if you need an exaggerated angle of view from a certain camera position. There is of course lens distortion itself, which is undesirable, but can be corrected for with software. It is also possible to change perspective to some extent in post-processing, but this will only control how angles will appear but not reduce the exaggerated angle of view.

BTW, the Tamron 10-24 has the most versatile range but is generally regarded as having worse IQ compared to the Pentax 12-24 and both Sigma 10-20 versions. Whether IQ is still sufficient is for the OP to decide.

I don't think that the Pentax 12-24/4 is necessarily better than the Sigma 10-20/3.5. This being a Pentax forum, you'll find many people praising the Pentax 12-24, but note that the Tokina 12-24 (has the same optical design as the Pentax 12-24 but is much cheaper for other mounts) is regarded as a "good" but not "outstanding" lens by Canikonians. The Sigma 10-20 (both versions) enjoys a large following; see the "Sigma 10-20 Club".
05-08-2011, 04:33 PM   #18
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
These points are understood.
Perspective distortion is a given in UWA lenses, and may not be a problem per se, however may be undesirable in some circumstances - in which case, as mentioned, stepping back with a longer focal length is required.

The DA 12-24 is not only praised by Pentaxians - independent lens reviewers seem to think it's a quality lens as well:

Pentax DA 12-24mm f/4 AL ED [IF] - Review / Test Report
"The sweet spot of the lens is at the wide end of the zoom range where the center quality is outstanding and the borders and even the extreme corners reach very good levels and that's already straight from f/4"
"The lens is less prone to flare compared to its Tokina variant"
Optical quality 3.5/5

Sigma AF 10-20mm f/4-5.6 EX DC (Pentax K) - Review / Test Report
"The resolution characteristic is generally very good to excellent except in the extreme corners at 10mm which are a bit soft at large aperture settings. A weak aspect of the Sigma is very high vignetting at large apertures - to be fair this is relatively normal regarding the extreme ultra-wide focal-length range."
Optical quality 3/5
(no f/3.5 version to compare with on K-mount tests, but on Nikon bodies the f/3.5 version did well though not necessarily better than the 12-24 - extreme corners are paltry at the wide end, and the usual vignetting and CA issues no different to other UWAs - scoring 3/5 also)

Tokina AT-X Pro SD 12-24mm F4 (IF) DX Lens Review: 4. Conclusion & samples: Digital Photography Review
Optical quality 8.5/10

LensTip.com - lens review, lenses reviews, lens specification - Lenstip.com
Optical quality 4/5

Last edited by Ash; 05-08-2011 at 04:39 PM.
05-08-2011, 09:55 PM   #19
Veteran Member




Join Date: Mar 2009
Location: Midwest
Photos: Gallery
Posts: 1,407
QuoteOriginally posted by Roy3 Quote
Hi Phil,

Have you checked out dpreview website? they give excellent very searching reviews of virtually all cameras.
The review conclusion of the Pentax K-5 scored 83 whilst the Canon D7 scored 84. The site has facility for comparing cameras side by side. The reviews are quite technical, way over my head, but very well written and I think they can be relied upon.
For Lenses, take a look at Fred Miranda website (FM Reviews -) dedicated to Canon & Nikon, but the members give their opinions of all the 3rd party lenses, it's a good guide to Lens performance. I do wish they would include the Pentax lenses, but they do include Tokina that's part of the Pentax group.

I have the K-5 along with the Pentax 17-70 Lens, it is a serious bit of kit, it brings a smile to my face every time I use it.
So far, it's the best camera I've used over the period 1947-2011, yeah! from the day's of plate cameras & wooden tripods to todays modern offerings, I've had & tried them all.

Get the K-5, you won't be disappointed.

Regards,

Roy
Reading your post is a relief. I've always prided myself on being pragmatic and as objective as I can, but every time I use the K-5 I get a big grin on my face, and I'm having more fun taking pictures than I have since the Seventies. Not as long a road as yours, but not inconsequential. I start wondering "Have I finally lost it? Have I finally become a FanBoy, who loves the product because of the brand, rather than the brand because of the product?" ... But with so many others expressing the same sentiments about the camera, I can - for the moment - believe that it really is that amazing a machine.

05-09-2011, 02:05 AM   #20
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 8,939
Regarding the photozone tests. No disrespect to Klaus who runs them, but regarding the stars he awards, I have my doubts as to useful they are.

I forgot which lens it was but it was one that was commonly regarded as great and the photozone score was 3. The FA 43 gets a 3.5. The FA 77 gets a 3.5 and the comment "Optically it doesn't offer much beyond the mainstream in this class...". At least the FA 31 gets a 4.5, but note that one of the best AF lenses ever doesn't make it to a 5.

Note that the Sigma 10-20/3.5 also gets a "4" for optical quality but a "4.2" overall, compared to the "3.67" for the Pentax 12-24/4. However, that doesn't matter much for me as I don't believe in review scores.

The OP should have a look at different lenses and then choose one that fits well for them, rather than how many stars someone figured out it may deserve. Even if you focus on optical quality only (which is just one aspect of a lens) then the score for this is an aggregate of many individual scores. For some it is more important to be able to correct lens distortion, others prefer to be able to correct CA. Typically no lens is better in all aspects, but it is a "give and take" competition. Aggregate scores are not helpful for deciding which lens is best for a particular individual.

Last edited by Class A; 05-09-2011 at 02:21 AM.
05-09-2011, 05:15 AM   #21
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
You know what, you're right.
Points on a review site don't mean all that much.
To me, the images they produce make the cut, and I'm sure all of the UWA offerings are up to par with top notch results if shot at around f/8 (and let's face it, how many landscapes/architecture shots do we need to shoot at wider than f/5.6 anyway?)
MTF data do show off the Sigma's optical weakness, but those weaknesses correct themselves quite remarkably by 14mm.
05-09-2011, 07:55 AM   #22
Veteran Member




Join Date: Mar 2009
Location: Midwest
Photos: Gallery
Posts: 1,407
QuoteOriginally posted by Class A Quote


Note that the Sigma 10-20/3.5 also gets a "4" for optical quality but a "4.2" overall, compared to the "3.67" for the Pentax 12-24/4. However, that doesn't matter much for me as I don't believe in review scores.
LOL! Exactly. For anyone who does place inordinate value in review stars, I have one of the aforementioned 10-20s, and I would happily trade it for a FA 43 ltd.
05-09-2011, 08:03 AM   #23
Veteran Member




Join Date: Mar 2009
Location: Midwest
Photos: Gallery
Posts: 1,407
QuoteOriginally posted by Ash Quote
You know what, you're right.
Points on a review site don't mean all that much.
To me, the images they produce make the cut, and I'm sure all of the UWA offerings are up to par with top notch results if shot at around f/8 (and let's face it, how many landscapes/architecture shots do we need to shoot at wider than f/5.6 anyway?)
MTF data do show off the Sigma's optical weakness, but those weaknesses correct themselves quite remarkably by 14mm.
I don't use the UWA much at all anymore since I learned how to do stitching easily in Photoshop - and then bought Autopano. The image quality of the stitched shots is so much higher than you can get with a single UWA shot, particularly for interiors and architecture. The only time I use the UWA is for group shots in close quarters (but mostly my 18-50 handles that), or when I'm looking for the particular visual distortion UWA provides.

05-09-2011, 10:38 AM   #24
Pentaxian




Join Date: Jul 2010
Location: Oregon
Photos: Albums
Posts: 1,417
QuoteOriginally posted by Class A Quote
Regarding the photozone tests. No disrespect to Klaus who runs them, but regarding the stars he awards, I have my doubts as to useful they are.



I would not pay much attention to the star ratings, bu the test numbers are quite useful.
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!
camera, dslr, k-5, k-5 ii, k-5 iis, k5, pentax k-5, photos, thread
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
New FA 31mm, couple questions mason Pentax SLR Lens Discussion 24 03-25-2011 02:27 AM
K5 questions Sifu Pentax K-5 19 02-20-2011 01:48 AM
K5 battery charger questions Javaslinger Troubleshooting and Beginner Help 2 02-05-2011 04:10 PM
K5 Video recording questions gybp Pentax K-5 4 11-13-2010 04:21 AM
Two questions about k5 Inspector 17 Pentax News and Rumors 15 09-20-2010 09:14 PM



All times are GMT -7. The time now is 08:35 AM. | See also: NikonForums.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