Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-31-2011, 01:56 AM   #46
Pentaxian




Join Date: Dec 2007
Location: Prague
Photos: Gallery
Posts: 1,198
QuoteOriginally posted by Raylon Quote
My Sigma 17-50 is ridiculous. Crazy sharp at all apertures, even with the demanding 7D 18MP sensor. Focus is lightning fast. I can't how people could give it a bad review.
Easy. You are lucky with better copy of this lens, while some others are not. The same goes for every f2,8 zoom in this category. We know that there are few bad DA16-50, bad Tamron 17-50 and bad Sigmas. But there are also great DA*16-50, great Tamrons and great Sigmas.
We all know that.
What is yet unknown is the percentage of the good, mediocre and bad for each brand, production run, internal revision and in cooperation with what specific camera model.
Also very important is how long will the good lens optical quality last, if deterioration of optical quality is covered by service under warranty and perhaps other factors.

04-01-2011, 02:27 AM   #47
Forum Member




Join Date: Dec 2007
Location: Moon
Posts: 86
QuoteOriginally posted by elho_cid Quote
I'm sorry to hear that yopu had this experience. I believe it is real on the moon where you live. But I really experienced a great DA*16-50 and wanted to share my optimism. Why should it be forbidden to share positive experience?
The Tamron, when new, may really have great optical performance. But what about after 2 years of usage? With it's built quality?
share positive experience all you want, i never said that people should stop posting positive things about specific item, what i ask for is to stop making claims that "issues of 16-50 being decentered is thing of the PAST" because it is NOT thing of the past....
04-01-2011, 10:06 AM   #48
Senior Member
Armanius's Avatar

Join Date: Mar 2011
Location: Houston, Texas
Photos: Gallery
Posts: 112
Just received the Tammy 17-50 and the Siggy 17-50!!

Will run some tests later on to see which one is the keeper (or perhaps neither). They are a whole lot closer in size than I thought. The Siggy didn't end up being as overbearing in size relative to the K-5's body as I thought it would.
04-01-2011, 05:13 PM   #49
Veteran Member
Tommot1965's Avatar

Join Date: Sep 2010
Location: Perth Western Australia
Photos: Gallery | Albums
Posts: 1,026
QuoteOriginally posted by Armanius Quote
Just received the Tammy 17-50 and the Siggy 17-50!!

Will run some tests later on to see which one is the keeper (or perhaps neither). They are a whole lot closer in size than I thought. The Siggy didn't end up being as overbearing in size relative to the K-5's body as I thought it would.
could you please post some images from both.... particularly at 17/50 mm wide open...

04-01-2011, 11:04 PM   #50
Forum Member




Join Date: Dec 2007
Location: Moon
Posts: 86
QuoteOriginally posted by Armanius Quote
Just received the Tammy 17-50 and the Siggy 17-50!!

Will run some tests later on to see which one is the keeper (or perhaps neither). They are a whole lot closer in size than I thought. The Siggy didn't end up being as overbearing in size relative to the K-5's body as I thought it would.
i'm dieing to hear how the sigma performed on your K5 AF wise
when i tried one it was outstanding lens, sharp all the way from 2.8 but only when i used live view focus because with normal autofocus especially outdoors i would have massive problems with AF on k5 with this lens, worked rock solid on k20
04-01-2011, 11:08 PM   #51
Veteran Member
Tommot1965's Avatar

Join Date: Sep 2010
Location: Perth Western Australia
Photos: Gallery | Albums
Posts: 1,026
QuoteOriginally posted by Croc Quote
i'm dieing to hear how the sigma performed on your K5 AF wise
when i tried one it was outstanding lens, sharp all the way from 2.8 but only when i used live view focus because with normal autofocus especially outdoors i would have massive problems with AF on k5 with this lens, worked rock solid on k20
me too..at 50 mm it was good, at 17mm its way out..
04-03-2011, 12:58 AM - 1 Like   #52
Senior Member
Armanius's Avatar

Join Date: Mar 2011
Location: Houston, Texas
Photos: Gallery
Posts: 112
Testing Sigma 17-50 vs. Tamron 17-50

DISCLAIMER: I'm not a pro. So if there are deficiencies and errors in my testing (and I'm sure there are), sorry!!!

Here are some 100% center crops of a very unscientific test that I conducted. The test parameters were:

- tripod
- body IS turned off, and lens IS (in Sigma) turned off
- lots of tungsten lighting
- running firmware 1.01 on Pentax K-5
- 2 second shutter timer
- I took photos at 17mm, 35mm, and 50mm
- apertures used at each focal length were 2.8, 5.6, 8
- photos in JPG, natural
- cropped in Lightroom 3.3 (tried my best to crop the same size image)
- focus point was single point centered on Polish flag
- ISO 800

My observations:

- Phase detect Tamron AF was a bit off at 17mm, 2.8, and image looked soft; however, using live view yielded a crisp image
- Phase detect Tamron AF was a bit off at 50mm, 2.8, as well. I forgot to take a live view shot at this focal length though.
- Phase detect for Sigma seemed right on at all focal lengths and apertures
- Notwithstanding the Tamron phase detect AF problems, the Sigma seemed a bit sharper

- Sigma is not much bigger than the Tamron, lengthwise. However, the diameter is relatively bigger. Sigma is also relatively heavier. IMO, the Sigma lens is disproportionately too fat for the K-5. However, It's my understanding the DA*16-50 is even chunkier than the Sigma.

- AF speed seemed about the same on both lenses. However, the HSM motor on the Sigma is nice and quiet. The Tamron is painfully loud.

- AF accuracy, as noted above, was lacking on the Tamron lens that I got. Bummer.

- The in-lens IS on the Sigma works pretty well. It's nice to see the IS working while looking through the OVF. However, when I first played with the Sigma in live view, with in-lens IS on and in-body IS off, the battery of the K-5 went from full (green) to empty (red). I turned the K-5 off and on, placed it in the OVF, and got a green battery sign again. Put it back on live view, and it went to red again. I put the Tamron on the K-5, put it in live view, and the battery was green. One day later, I did the same thing with the Sigma in live view, and the battery was green all the time. Weird.

Also took some shots at 22mm to compare with the Pentax DA21. My observations:

- Sigma is sharper than DA21 at 3.2
- Tamron is comparable to DA21 at 3.2

Overall conclusions:

- The Sigma seems to perform better than the Tamron, and performance wise (silent AF, more accurate AF, sharper, nice in lens IS), it's worth the extra $240. But it's a bit too chunky for me.
- 50mm is a little restrictive for me too. I am returning the Tamron for sure. I may return the Sigma as well, and try out the Pentax 18-135. Maybe I don't really need the constant F2.8.


I am not posting the full size photos as they are about 10 megs each. If you want them, and also want the F8.0 photos, PM me. Enjoy!


Here is the first batch of crops - 17mm at 2.8

Tamron 17mm, 2.8, using phase detect:



Tamron 17mm, 2.8, using live view contrast detect:



Sigma 17mm, 2.8


Last edited by Armanius; 04-03-2011 at 01:25 AM.
04-03-2011, 01:01 AM   #53
Senior Member
Armanius's Avatar

Join Date: Mar 2011
Location: Houston, Texas
Photos: Gallery
Posts: 112
Second batch of photos, 17mm, 5.6

Tamron 17mm, 5.6



Sigma 17mm, 5.6



04-03-2011, 01:05 AM   #54
Senior Member
Armanius's Avatar

Join Date: Mar 2011
Location: Houston, Texas
Photos: Gallery
Posts: 112
Third batch, 50mm, 2.8 and 5.6

Tamron 50mm, 2.8



Sigma 50mm, 2.8



Tamron 50mm, 5.6



Sigma 50mm, 5.6

04-03-2011, 01:08 AM   #55
Senior Member
Armanius's Avatar

Join Date: Mar 2011
Location: Houston, Texas
Photos: Gallery
Posts: 112
Fourth batch, comparisons with the Pentax DA21, 21mm, 3.2

Pentax DA21, 21mm, 3.2



Tamron 21.77mm, 3.2



Sigma 22mm, 3.2

04-03-2011, 01:12 AM   #56
Veteran Member
FotoPete's Avatar

Join Date: Feb 2007
Location: Toronto
Photos: Gallery
Posts: 1,710
Seems like the live view contrast detect is alot more fool proof than the phase AF, static scene wise.
04-03-2011, 01:20 AM   #57
Senior Member
Armanius's Avatar

Join Date: Mar 2011
Location: Houston, Texas
Photos: Gallery
Posts: 112
It sure seemed that way with the Tamron at least.

QuoteOriginally posted by FotoPete Quote
Seems like the live view contrast detect is alot more fool proof than the phase AF, static scene wise.
04-03-2011, 01:28 AM   #58
Junior Member




Join Date: Apr 2008
Location: Stockholm, Sweden
Posts: 35
Be more objective

QuoteOriginally posted by elho_cid Quote
welcome!
please do not be offended by the lack of response. But the lens you are asking about is not very attractive. Usually people buy Tamron if they are limited by budget or DA* pentax when they want the best standard zoom.
Sigma doesn't seem attractive to many in this competition.
Now you are unfair to this Sigma lens. My Sigma 17-50mm/2.8 is the one before today´s version with HSM and it gives me very good IQ, already with the widest aperture (as confirmed by the test in Photozone). I would not have bought it if the reviews had told me that Tamron was clearly better. Tamron certainly has its flaws and, according to some reviewers, absolutely more flaws than the Sigma.
Please, try to be more objective, or the readers of this forum will not miss your comments if you go somewhere else!
By the way, you can read what Armanius reports just before me here on page 4 of this thread. Then you will understand my strong objection against the biased standpoint that you pronounce!

Last edited by Staffan; 04-03-2011 at 01:38 AM. Reason: Forgot title
04-03-2011, 07:50 AM   #59
Veteran Member
pop4's Avatar

Join Date: Aug 2007
Location: YMML
Photos: Gallery
Posts: 1,877
QuoteOriginally posted by Staffan Quote
Now you are unfair to this Sigma lens. My Sigma 17-50mm/2.8 is the one before today´s version with HSM and it gives me very good IQ, already with the widest aperture (as confirmed by the test in Photozone). I would not have bought it if the reviews had told me that Tamron was clearly better.
Are you talking about the Sigma 18-50mm/2.8? I don't think Sigma ever released a 17-50mm/2.8 other than the current version with HSM and OS.

As far as I know, Sigma has the:

18-50mm/2.8
18-50mm/2.8 Macro
18-50mm/2.8 Macro HSM (But this was for Nikon mount only)
17-50mm/2.8 HSM OS
04-03-2011, 03:36 PM   #60
Forum Member




Join Date: Dec 2007
Location: Moon
Posts: 86
thanks for posting the photos and your review Armanius
any chance you could test sigma outdoors? when i testes indoors with focus chart i was orginaly very excited about this lens but leter when i tested outdoors doing normal pictures and not printed pages and full sun in daylight conditions the focus was real shocker on k5
i would buy another copy if it turns out it was just once off sample that had problem but i think issue is k5 focusing and not lens itself.
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, f/2.8, hsm, k-5, k-5 ii, k-5 iis, k5, os, pentax k-5, sigma, sigma 17-50mm f/2.8
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sigma 17-50mm F2.8 EX DC OS HSM v Tamron 17-50mm f/2.8 XR Di-II LD Aspherical [IF] lmd91343 Pentax SLR Lens Discussion 6 05-25-2011 07:04 PM
Pentax SMCP-FA 50mm f/1.4 Lens or Sigma 50mm f/1.4 EX DC HSM? NicK10D Pentax DSLR Discussion 7 06-23-2010 06:21 AM
the New Sigma 17-50mm F2.8 EX DC OS HSM gr8wings Pentax SLR Lens Discussion 1 03-28-2010 08:26 AM
Sigma 50mm f/1.4 EX DG HSM Mann Pentax SLR Lens Discussion 5 07-06-2009 02:40 AM
Sigma 50mm f1.4 EX DG HSM ? Big G Pentax SLR Lens Discussion 25 05-22-2009 05:59 AM



All times are GMT -7. The time now is 09:28 PM. | 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