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12-26-2012, 01:22 PM   #1
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Is the Sigma 17-50mm f/2.8 much better than the Pentax DA 16-45mm f/4 ?

I'm on the verge of buying the Sigma 17-50mm f/2.8, as the price is really interesting at the moment and f/2.8 is really nice for portraits or low-light.

However I'm wondering if it would be a really big improvement over my Pentax DA 16-45mm f/4, which is sharp with nice Pentax colours and good close focus capabilities.

I have owned a Pentax DA* 16-50mm f/2.8 for a few months, but was dissapointed by its average sharpness, and eventually sold it.

Weather sealing was really nice, but not always necessary.

Should I go for the Sigma, or keep my trusty Pentax
16-45 ?

Thanks in advance for your help.

12-26-2012, 03:04 PM   #2
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The sigma is much sharper than the 16-50 in my experience. I've also found the color palette to be a lot more neutral on the sigma, whereas the DA* would have quite a lot more pop to its images SOOC, which is likely due to it having higher contrast and more vibrant colors.

If low-light is important to you, go for the sigma. otherwise, stick with your 16-45, its a solid performer as long as you don't need f2.8
12-26-2012, 03:06 PM   #3

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I have had my sigma 17-50 for about a week and it was what I had hoped for but was not expecting. In the week if I have had it i would say the colours have been to my high standard. This sigma zoom lens is slightly softer than my primes which I would say is within expectations. This sigma zoom is miles better than my sigma 17-70 and pentax 17-55WR. I have never used the pentax 16-45. I didn't want the pentax 16-50 due to its high level of failure and was hanging out for the new pentax lens. However i got my sigma at a bargain price as it had been a display model.
12-27-2012, 03:57 PM   #4
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How sharp is the 17-50 when opened to f2.8? The 24-75 is z touch too soft for my liking.

12-27-2012, 10:30 PM   #5
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I have Pentax 16-50 and Sigma 17-50 f2.8. I have been testing the pentax extensively. My copy is very sharp in the middle but soft at extreme edge wide opened.
I have been lucky so far with no mechanical issues with K5 or Da16-50.
Pentax zoom draws differently from the Sigma. The colour is the biggest difference. The Pentax looks better built c/w Sigma. If you are after the 'Pentax look', get the Da 16-50. However, i will pay US750 but not more for this lens. Otherwise Sigma is of better value.
All the best.
12-28-2012, 10:28 PM   #6
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What about flare resistance? I also wanted to buy this lens but when I saw flare test images in the comparison on this site I reconsidered... Am I overreacting? My problem is that even when the sun is not in the frame it still damages the shots... maybe the proper hood can help though?
12-28-2012, 10:52 PM   #7
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DA 16-50 is prompt to flare at wide end. I will not leave the hood off ...
Can't comment on Sigma as i have not used it much so far...
12-29-2012, 10:00 AM   #8
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Thanks for the answers so far.

Flare resistance is also a big concern for me, as the DA 16-45 is very good in this regard.

Sigma color rendition appears a bit warm for my liking but that can be fixed easily if shooting RAW.

According to reviews the Sigma is sharp in the center at 2.8 at all focal lengths, which is not the case of its competitors, I found the DA 16-50 very soft at this setting.

12-31-2012, 04:23 AM   #9

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QuoteOriginally posted by Bestzoom Quote
The Pentax looks better built c/w Sigma. If you are after the 'Pentax look', get the Da 16-50. However, i will pay US750 but not more for this lens. Otherwise Sigma is of better value.
All the best
Eerrr, I'll have to disagree on that one. Most would state the Sigma one is actually built better.

But also, if one can spare the minor difference in focal length and also deal with both the size and weight of such as lens… The Sigma 24-70 f2.8 is nothing short of incredible; it's what most Pentax lens' dream of being
01-02-2013, 05:02 PM   #10
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I am not sure about the Pentax 16-45 but I used to own the Pentax 17-70 f4 so I can compare the Sigma to this. The Sigma 17-50 f2.8 is my current walk around lens. The Sigma is very sharp wide open at 2.8 and extremely sharp stopped down a little. It easily beats the Pentax 17-70 which was soft wide open. The main advantages of the Pentax is build (bit better than Sigma) and colour rendition (Sigma is a touch cooler). Overall I am very happy with the Sigma. Most of my shots are wide open or near wide open so the sharpness really makes a difference to my photos.

Also I never noticed any problems with soft corners with the Sigma as reported.

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