Is the Sigma 17-50 2.8 a better lens than the 20-40 Limited?

sarge · 04-25-2016, 05:01 PM

I am thinking about selling my Pentax 20-40 Limited and getting a Sigma 17-50 2.8.
I am happy with the IQ of the Pentax but find myself wishing for better range and that extra stop of light at the long end.
The Sigma seems to be priced very low, that kind of concerns me. Is it a good lens priced at a bargain, or is it not so great and priced accordingly?

**UncleVanya** · 04-25-2016, 05:36 PM

That lens has a really good reputation.
Sigma Lenses for Pentax: Current Zoom Lenses - Pentax Lens Review Database

Adam · 04-25-2016, 05:54 PM

Originally posted by sarge

I am thinking about selling my Pentax 20-40 Limited and getting a Sigma 17-50 2.8.
I am happy with the IQ of the Pentax but find myself wishing for better range and that extra stop of light at the long end.
The Sigma seems to be priced very low, that kind of concerns me. Is it a good lens priced at a bargain, or is it not so great and priced accordingly?

It's an older lens, hence the attractive price tag. Optically it's quite good, I wouldn't hesitate to pick up a copy!

vinceloc · 04-25-2016, 06:04 PM

Just got one. I am satisfied with it. IMHO, in terms of sharpness and color rendition, it provides much better value than the 20-40ltd., considering you can get one new for $375-400. But it is bigger and heavier than the 20-40ltd. So if you want a smaller and lighter system, then it is not the way to go. I too was choosing between a used 20-40ltd. and a new Sig17-50/2.8. After checking out (pixel peeping) the photos of some sellers of the 20-40ltd., I came to the conclusion that it would be too big a risk for me to pay $500+ for a used lens that doesn't satisfy my standard. So, I went for a new Sigma. Sigma has improved tremendously through the years in glass. I have owned several Sigmas in the past, and the color rendition of the 17-50/2.8 is much more the color I prefer than before. More Pentaxish and Voigtlanderish.

One3rdEV · 04-25-2016, 06:46 PM

Back in 2012 when the Sigma 17-50 f2.8 was new.. according to DXO it delivered the highest peak resolution rating of any lens which they had data available for using the Nikon D7000 (this included fixed focal length lenses). At that time there were very few image samples from it available on the web, so I bought it based on specs alone. This was not a bad move at all since it delivers very good to excellent images.

However, within a couple of years later I decided to buy the DA 18-135 mm lens for the purpose of family vacations and activities. This was primarily because I wanted a single lens solution with longer reach and WR. The slightly smaller size and weight of the 18-135 mm has been a little beneficial also. The WR has proven to be very important for me as I've expanded to using the lens with my outdoor water based activities.

I figured that since the DA 18-135 mm lens had such good center resolution, I could sell the Sigma. However, as much as I enjoy the many outstanding images I get from the DA 18-135 mm- if I shoot identical images, the Sigma demonstrates visibly greater micro-contrast and 3-dimensional rendering. To be honest, this really surprised me because I expected the Pentax glass to excel in these two areas. If I compare to my Zeiss Hasselblad medium format lenses (which I consider to create very real-life rendering), the Sigma renders quite similarly. Mind you I love my Pentax glass, and I also love the continuous flow of images taken by others using Pentax lenses. So I just don't bother to compare the lenses any more. But consequently, I don't see myself being able to sell the Sigma, even though I presently use the DA considerably more.

**ismaelg** · 04-25-2016, 06:48 PM - **1 Like**

I just bought a Tamron 17-50 f2.8 and initial impression is very good.
There is a review comparing the Tamron 17-50, the Sigma 17-50 and the Pentax 16-50

DA* 16-50mm vs. Sigma and Tamron 17-50mm F2.8 Comparison Review - Introduction | PentaxForums.com Reviews

Thanks,

**ramseybuckeye** · 04-25-2016, 07:18 PM

I recently bought the Sigma and I am quite pleased, though I am still learning the characteristics of the lens. Sorry, I can't compare it to the 20-40 as I have never used one. I also have and love the DA18-135, but I bought the Sigma for indoors and lower light. I actually expected the lens to be larger. I am using it in the Singles challenge this month to get to know it better. The lens seems to be very sharp, I've no complaints.

Craig66 · 04-25-2016, 08:48 PM

Sigma 17-50F2.8 is a great lens. Very happy with mine.

**clackers** · 04-25-2016, 10:02 PM

Originally posted by sarge

The Sigma seems to be priced very low, that kind of concerns me. Is it a good lens priced at a bargain, or is it not so great and priced accordingly?

Don't be worried by the price, Sarge, it's a wonderful lens.

Simen1 · 04-26-2016, 12:04 AM

The Sigma are probably great optically, but quality comes at a price. In this case the Sigma (565g) weights exactly the double of the Pentax (283g), and its a little longer and wider. Note that the difference in focal lengths are quite small. 25% longer at tele and 15% wider at the wide end (Quasi-math). How does the Pentax and the Sigma fit in between the properties of the other lenses you have?

sarge · 04-26-2016, 02:31 AM - **1 Like**

Originally posted by Simen1

The Sigma are probably great optically, but quality comes at a price. In this case the Sigma (565g) weights exactly the double of the Pentax (283g), and its a little longer and wider. Note that the difference in focal lengths are quite small. 25% longer at tele and 15% wider at the wide end (Quasi-math). How does the Pentax and the Sigma fit in between the properties of the other lenses you have?

I currently have the 15 Limited on the wide end and use the 55-300 HD for tele needs. I need the DOF on the long end for weddings. I can use the 50 1.8 I have now but it requires a lens change and that opens up the chance to miss a shot during a wedding ceremony. When I got the 20-40 I had really thought about the 17-50 but decided to go with the Pentax due to weather sealing. I have come to realize I need the reach and DOF more than the weather sealing.

k22 · 04-26-2016, 06:08 AM

I see this lens on the bay for under $300 shipped from Japan. Not sure what the downside is other than warranty...

**UncleVanya** · 04-26-2016, 07:08 AM

Originally posted by sarge

I currently have the 15 Limited on the wide end and use the 55-300 HD for tele needs. I need the DOF on the long end for weddings. I can use the 50 1.8 I have now but it requires a lens change and that opens up the chance to miss a shot during a wedding ceremony. When I got the 20-40 I had really thought about the 17-50 but decided to go with the Pentax due to weather sealing. I have come to realize I need the reach and DOF more than the weather sealing.

For weddings the stock answer is for minimal kit is:

DA* 16-50 f2.8
DA* 50-135 f2.8
With two bodies If possible (both for convenience and backup in case of problems).

The 17-50 f2.8 is a good substitute for the 16-50 with no real downsides other than loss of weather sealing.

With the 17-50 you could add a 70 or larger prime on a second body if the 50-135 is out of reach financially. I personally wouldn't want to shoot a wedding without a backup body so that would be the first priority for me I think.

You might try trading your 20-40 for a backup body or the 17-50 and some cash.

sarge · 04-26-2016, 08:01 AM

Originally posted by UncleVanya

For weddings the stock answer is for minimal kit is:

DA* 16-50 f2.8
DA* 50-135 f2.8
With two bodies If possible (both for convenience and backup in case of problems).

The 17-50 f2.8 is a good substitute for the 16-50 with no real downsides other than loss of weather sealing.

With the 17-50 you could add a 70 or larger prime on a second body if the 50-135 is out of reach financially. I personally wouldn't want to shoot a wedding without a backup body so that would be the first priority for me I think.

You might try trading your 20-40 for a backup body or the 17-50 and some cash.

I have a K-S2.
Won't go with any of the Pentax SDM lenses due to the motors failing.
I do have the 70 Limited and the 50 1.8 I have shot weddings in the past and very very rarely used anything beyond 70mm. My style is right up in the action.

**UncleVanya** · 04-26-2016, 08:12 AM

Originally posted by sarge

I have a K-S2.
Won't go with any of the Pentax SDM lenses due to the motors failing.
I do have the 70 Limited and the 50 1.8 I have shot weddings in the past and very very rarely used anything beyond 70mm. My style is right up in the action.

KS-2 is a great camera. The SDM issue is not entirely a Pentax only thing - other silent motor lenses have failed for other camera companies also but SDM seems to have poor long term reliability sometimes. The conversion to screw drive option on the 16-50, 50-135, 200 and 300 makes these less of a concern (and sometimes a bargain).

Given this info maybe the 17-50 plus the 70 mounted on a second body in the future. The 17-50 has a focusing motor but it seems reliable from all accounts.

04-25-2016, 05:01 PM	#1
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460	Is the Sigma 17-50 2.8 a better lens than the 20-40 Limited? I am thinking about selling my Pentax 20-40 Limited and getting a Sigma 17-50 2.8. I am happy with the IQ of the Pentax but find myself wishing for better range and that extra stop of light at the long end. The Sigma seems to be priced very low, that kind of concerns me. Is it a good lens priced at a bargain, or is it not so great and priced accordingly?

04-25-2016, 05:54 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,607	Originally posted by sarge I am thinking about selling my Pentax 20-40 Limited and getting a Sigma 17-50 2.8. I am happy with the IQ of the Pentax but find myself wishing for better range and that extra stop of light at the long end. The Sigma seems to be priced very low, that kind of concerns me. Is it a good lens priced at a bargain, or is it not so great and priced accordingly? It's an older lens, hence the attractive price tag. Optically it's quite good, I wouldn't hesitate to pick up a copy! Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

04-25-2016, 06:46 PM	#5
One3rdEV Senior Member Join Date: Mar 2013 Location: So-central, MI Posts: 285	Back in 2012 when the Sigma 17-50 f2.8 was new.. according to DXO it delivered the highest peak resolution rating of any lens which they had data available for using the Nikon D7000 (this included fixed focal length lenses). At that time there were very few image samples from it available on the web, so I bought it based on specs alone. This was not a bad move at all since it delivers very good to excellent images. However, within a couple of years later I decided to buy the DA 18-135 mm lens for the purpose of family vacations and activities. This was primarily because I wanted a single lens solution with longer reach and WR. The slightly smaller size and weight of the 18-135 mm has been a little beneficial also. The WR has proven to be very important for me as I've expanded to using the lens with my outdoor water based activities. I figured that since the DA 18-135 mm lens had such good center resolution, I could sell the Sigma. However, as much as I enjoy the many outstanding images I get from the DA 18-135 mm- if I shoot identical images, the Sigma demonstrates visibly greater micro-contrast and 3-dimensional rendering. To be honest, this really surprised me because I expected the Pentax glass to excel in these two areas. If I compare to my Zeiss Hasselblad medium format lenses (which I consider to create very real-life rendering), the Sigma renders quite similarly. Mind you I love my Pentax glass, and I also love the continuous flow of images taken by others using Pentax lenses. So I just don't bother to compare the lenses any more. But consequently, I don't see myself being able to sell the Sigma, even though I presently use the DA considerably more. Last edited by One3rdEV; 04-25-2016 at 07:01 PM.

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04-25-2016, 05:36 PM	#2
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,449	That lens has a really good reputation. Sigma Lenses for Pentax: Current Zoom Lenses - Pentax Lens Review Database

04-25-2016, 06:04 PM	#4
vinceloc Veteran Member Join Date: Jul 2007 Location: Philippines Photos: Gallery Posts: 367	Just got one. I am satisfied with it. IMHO, in terms of sharpness and color rendition, it provides much better value than the 20-40ltd., considering you can get one new for $375-400. But it is bigger and heavier than the 20-40ltd. So if you want a smaller and lighter system, then it is not the way to go. I too was choosing between a used 20-40ltd. and a new Sig17-50/2.8. After checking out (pixel peeping) the photos of some sellers of the 20-40ltd., I came to the conclusion that it would be too big a risk for me to pay $500+ for a used lens that doesn't satisfy my standard. So, I went for a new Sigma. Sigma has improved tremendously through the years in glass. I have owned several Sigmas in the past, and the color rendition of the 17-50/2.8 is much more the color I prefer than before. More Pentaxish and Voigtlanderish.

04-25-2016, 06:48 PM - 1 Like	#6
ismaelg Loyal Site Supporter Join Date: Apr 2009 Location: Puerto Rico Photos: Gallery Posts: 2,683	I just bought a Tamron 17-50 f2.8 and initial impression is very good. There is a review comparing the Tamron 17-50, the Sigma 17-50 and the Pentax 16-50 DA* 16-50mm vs. Sigma and Tamron 17-50mm F2.8 Comparison Review - Introduction \| PentaxForums.com Reviews Thanks,

04-25-2016, 07:18 PM	#7
ramseybuckeye Site Supporter Join Date: Apr 2009 Location: Hampstead, NC Photos: Gallery Posts: 17,295	I recently bought the Sigma and I am quite pleased, though I am still learning the characteristics of the lens. Sorry, I can't compare it to the 20-40 as I have never used one. I also have and love the DA18-135, but I bought the Sigma for indoors and lower light. I actually expected the lens to be larger. I am using it in the Singles challenge this month to get to know it better. The lens seems to be very sharp, I've no complaints.

04-25-2016, 08:48 PM	#8
Craig66 Senior Member Join Date: Sep 2010 Location: Sapphire Coast. NSW. Posts: 141	Sigma 17-50F2.8 is a great lens. Very happy with mine.

04-25-2016, 10:02 PM	#9
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by sarge The Sigma seems to be priced very low, that kind of concerns me. Is it a good lens priced at a bargain, or is it not so great and priced accordingly? Don't be worried by the price, Sarge, it's a wonderful lens.

04-26-2016, 12:04 AM	#10
Simen1 Veteran Member Join Date: Jul 2009 Location: Tromsø, Norway Photos: Albums Posts: 1,031	The Sigma are probably great optically, but quality comes at a price. In this case the Sigma (565g) weights exactly the double of the Pentax (283g), and its a little longer and wider. Note that the difference in focal lengths are quite small. 25% longer at tele and 15% wider at the wide end (Quasi-math). How does the Pentax and the Sigma fit in between the properties of the other lenses you have?

04-26-2016, 02:31 AM - 1 Like	#11
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460 Original Poster	Originally posted by Simen1 The Sigma are probably great optically, but quality comes at a price. In this case the Sigma (565g) weights exactly the double of the Pentax (283g), and its a little longer and wider. Note that the difference in focal lengths are quite small. 25% longer at tele and 15% wider at the wide end (Quasi-math). How does the Pentax and the Sigma fit in between the properties of the other lenses you have? I currently have the 15 Limited on the wide end and use the 55-300 HD for tele needs. I need the DOF on the long end for weddings. I can use the 50 1.8 I have now but it requires a lens change and that opens up the chance to miss a shot during a wedding ceremony. When I got the 20-40 I had really thought about the 17-50 but decided to go with the Pentax due to weather sealing. I have come to realize I need the reach and DOF more than the weather sealing.

04-26-2016, 06:08 AM	#12
k22 Site Supporter Join Date: Dec 2015 Posts: 153	I see this lens on the bay for under $300 shipped from Japan. Not sure what the downside is other than warranty...

04-26-2016, 07:08 AM	#13
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,449	Originally posted by sarge I currently have the 15 Limited on the wide end and use the 55-300 HD for tele needs. I need the DOF on the long end for weddings. I can use the 50 1.8 I have now but it requires a lens change and that opens up the chance to miss a shot during a wedding ceremony. When I got the 20-40 I had really thought about the 17-50 but decided to go with the Pentax due to weather sealing. I have come to realize I need the reach and DOF more than the weather sealing. For weddings the stock answer is for minimal kit is: DA* 16-50 f2.8 DA* 50-135 f2.8 With two bodies If possible (both for convenience and backup in case of problems). The 17-50 f2.8 is a good substitute for the 16-50 with no real downsides other than loss of weather sealing. With the 17-50 you could add a 70 or larger prime on a second body if the 50-135 is out of reach financially. I personally wouldn't want to shoot a wedding without a backup body so that would be the first priority for me I think. You might try trading your 20-40 for a backup body or the 17-50 and some cash.

04-26-2016, 08:01 AM	#14
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460 Original Poster	Originally posted by UncleVanya For weddings the stock answer is for minimal kit is: DA* 16-50 f2.8 DA* 50-135 f2.8 With two bodies If possible (both for convenience and backup in case of problems). The 17-50 f2.8 is a good substitute for the 16-50 with no real downsides other than loss of weather sealing. With the 17-50 you could add a 70 or larger prime on a second body if the 50-135 is out of reach financially. I personally wouldn't want to shoot a wedding without a backup body so that would be the first priority for me I think. You might try trading your 20-40 for a backup body or the 17-50 and some cash. I have a K-S2. Won't go with any of the Pentax SDM lenses due to the motors failing. I do have the 70 Limited and the 50 1.8 I have shot weddings in the past and very very rarely used anything beyond 70mm. My style is right up in the action.

04-26-2016, 08:12 AM	#15
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,449	Originally posted by sarge I have a K-S2. Won't go with any of the Pentax SDM lenses due to the motors failing. I do have the 70 Limited and the 50 1.8 I have shot weddings in the past and very very rarely used anything beyond 70mm. My style is right up in the action. KS-2 is a great camera. The SDM issue is not entirely a Pentax only thing - other silent motor lenses have failed for other camera companies also but SDM seems to have poor long term reliability sometimes. The conversion to screw drive option on the 16-50, 50-135, 200 and 300 makes these less of a concern (and sometimes a bargain). Given this info maybe the 17-50 plus the 70 mounted on a second body in the future. The 17-50 has a focusing motor but it seems reliable from all accounts.