Sigma 17-70 or Pentax 18-135 for my K50

aproud1 · 05-26-2015, 06:34 AM

All set to dive back into Pentax DSLR world. Unfortunately sold all of my lenses with my K10D. I'm pretty set on the K50 (size, price and performance) And want to get the best lens I can for my needs.

Looking at two options being about the same price:

1. K50 Kit with 18-135 WR, And Pentax DA50 1.8

2. K50 with new Sigma 17-70

I like taking close up and landscape pics. The only real portrait type pictures are typically bass guitars. Also do a lot of indoor shots.

So how does the 17-70 do indoors? Option one seems like the best deal but the Sigma looks like a really great lens. I figure I could use it until I can afford more lenses down the road. Depending on how it does in lower light.

Thanks for any advice!
Andy

sterretje · 05-26-2015, 07:02 AM

PF posted a review of the 17-70 contemporary. Conclusion is that it is superior to the 18-135 from an IQ perspective.

https://www.pentaxforums.com/reviews/sigma-17-70mm-f28-4-contemporary/conclusion.html

I assume it's also faster over the whole range which is beneficial for indoors.

Only WR snd/or the extra reach are in favor of the 18-135.

If you don't take cost into account, I would opt for the 17-70.

normhead · 05-26-2015, 07:02 AM - **1 Like**

Sigma 17-70 2.8 - 4.5
Pentax 18-135 3.5-5.6

For indoor shooting the Sigma is only about a half stop faster, that's probably not going to make any difference very often.
The 18-135, is clearly the most versatile.

The arguments on these two are endless.
I've never seen anyone with an 18-135 convince a Sigma 17-70 owner to switch.
I've never seen a Sigma 17-70 owner convince an 18-135 owner to switch.
The arguments either way are not terribly convincing. That being said I've seen a lot more excellent images produced by the 18-135, but then, a lot more people own it as far as I can tell, so that's not the best.

In cases like this I usually go with the lens that's made by Pentax. There are advantages in lens identification in my software etc by staying with Pentax gear.

For landscape the DA*18-135 works fine unless you go over 50mm, at 135 it still has excellent centre sharpness for pseudo macro images. The 17-70m is sharper edge to edge from 50-70mm, but still falls behind in centre sharpness.

I wouldn't give up the 70-135 end of the 18-135. But lots of people will be arguing that they don't use it. So you just need to figure out what kind of shooter you are.

Forget the "17-70 has better IQ argument. it's nonsense based on very minor differences.

The Sigma 17-70 is more consistent edge to edge, the 18-135 is better for centre sharpness. These are two different lenses, but, from 24mm to 35mm you won't see a lot of difference between them centre or border.

Some guy deciding one of these lenses is better than the other, is simply stating his or her personal shooting preference, if you don't shoot his/her style, their analysis won't apply to you.

http://www.photozone.de/Reviews/312-sigma-af-17-70mm-f28-45-dc-macro-test-report--review

http://www.photozone.de/pentax/597-pentax_18135_3556?start=1

I shoot a lot of images from 50-135 where centre sharpness is more important than edge sharpness, so i like the 18-135, and at 24 mm the 18-135 is right up there with the best lenses on K-mount, as a landscape len, excellent centre and edge.. If I were to pick a point at which the 17-170 really shines it would probably for 40mm edge to edge. But I have a 40 XS prime that's better than both of them and is ƒ2.8, and is quite cheap.

My 18-135 slideshow.

pathdoc · 05-26-2015, 08:00 AM

If I were starting out in the Pentax world today, I would get the 18-135 and DA 50 kit. (Did I read that right? They're offering both together? Or are you getting the 50 with what's left over if you don't get the Sigma?)

IMO the extra reach and WR capability is worth a small loss in image quality and raw speed on your primary zoom lens. And having the DA 50 as well will put you in a good place for portrait and low-light or narrow-DOF work. I have the DA 50 and it's lovely. I admittedly don't have the 18-135, but I know what I'd be doing in your shoes.

HYS · 05-26-2015, 08:04 AM

But it seems that 18-135 is discontinued.

normhead · 05-26-2015, 08:13 AM

Originally posted by HYS

But it seems that 18-135 is discontinued.

Someone forgot to tell Pentax Canada

smc PENTAX-DA 18-135mm F3.5-5.6 ED AL[IF] DC WR?Lenses?RICOH IMAGING CANADA

Or Henry's
PENTAX DA 18-135MM F3.5-5.6 ED WR 21977

Or B&H
Pentax SMC DA 18-135mm F/3.5-5.6 ED AL (IF) DC WR Lens 21977 B&H

But apparently there is some reliable source somewhere who knows more than suppliers and vendors.

not

pathdoc · 05-26-2015, 08:17 AM

"Discontinued" and "There are no more available anywhere" are two very different things.

normhead · 05-26-2015, 08:53 AM

Originally posted by pathdoc

"Discontinued" and "There are no more available anywhere" are two very different things.

The same thing happened to a couple of lenses when they stopped the old production lines and updated them for HD coatings.

iss2012 · 05-26-2015, 09:11 AM - **1 Like**

I have the 17-70 and for me it is very good for landscape (wide angle) and portrait (70 is nice). A detail that can make the difference is the "macro" (which is not real macro, but close to) feature that sigma has, you said that you want close up pictures so this feature is maybe what makes the difference between the two lenses. For the additional reach of the 18-135 you have to figure out if you will really need it or not. For me, 17-70 is a very versatile lense and perfect to begin with.

some shots I took with are in my flickr if interested
https://www.flickr.com/photos/117312932@N02/

normhead · 05-26-2015, 09:23 AM

I have lots of images using the 18-135 as a pseudo macro....

IN fact, the superior centre sharpness of the 18-135 makes it almost a perfect macro lens, unless you're photographing microchips.

DA 18-135 pseudo macro slideshow.

I have a SIgma 18-250 and 70-300 both labeled macro which don't do as good a job as the 18-135. My Sigma 70 macro though.. now that is a macro lens.

Sigma plays a little looser with the term macro than Pentax does. 1:2, is good enough for Sigma, 1:1 seems to be the norm for Pentax.

MPrince · 05-26-2015, 09:43 AM

Originally posted by normhead

I've never seen anyone with an 18-135 convince a Sigma 17-70 owner to switch.
I've never seen a Sigma 17-70 owner convince an 18-135 owner to switch.

I've convinced a 17-70 owner to switch to the 18-135.

The 17-70 owner I convinced to switch was...me!

iss2012 · 05-26-2015, 09:58 AM

Originally posted by MPrince

I've convinced a 17-70 owner to switch to the 18-135.

The 17-70 owner I convinced to switch was...me!

Could you develop more the reasons behind ? Maybe you could add me to the converted list

aldorp · 05-26-2015, 10:02 AM - **4 Likes**

I own both the new Sigma 17-70 and Pentax 18-135 and I use them in very different ways.

In my house we call the Pentax 18-135 "Jack of All trades and Master of None". This is the lens I take when I have no idea what to expect and have little desire (or capability) of changing lenses on the go. I own 11 or 12 Pentax lenses and I can beat EVERY SINGLE focal length and aperture setting of the Pentax 18-135 with another lens I own. On the other hand it takes me 2 or 3 lenses to cover everything this lens does. So this lens is amazing for it's flexibility but not for it's optical quality. Having said that it has good center sharpness and from 18 - 100mm it has acceptable borders if you close it one or two stops. That this lens is weather seal is good too and adds to the versatility factor of the lens. I once had to do an outdoors wedding with this lens (It rained on that wedding, this was one of the few WR lenses I had on me) and it did not disappoint so please understand that this is not a bad lens. I just have better glass, especially if I bring out my primes and for quality this lens would never be my first choice.

The Sigma 17-70 is a TOTALLY different beast (regardless of what the reviews on this site say). This lens has great center at 17mm wide open with terrible border sharpness.This weakness can be minimized at f5.6 or f8.0 but is never fully solved at 17mm. This is NOT a great wide angle lens (and neither is the Pentax 18-135 for that matter). From 24mm to 70mm this lens kicks ass and starts taking down names. Very sharp wide open and gets better closing one stop at both center and borders. From 50mm to 70mm it is AMAZING wide open (f4.0) and perfect for portraits and what I use use it most often. This lens can show you what a Pentax is truly capable off doing. The macro capabilities of this lens is also very good for close up photography (not a true macro, macro is at least 1:1) and the lens is faster overall than the Pentax 18-135, but of course the Pentax reaches farther.

Having said that both lenses have something that is VERY important these days; good auto-focus performance for both speed and accuracy. Truth be told it does not matter how good a lens is, if it can't focus properly it is no better than a kit lens. Both lenses have very good track records in getting the shoots I want.

So if you want a very versatile lens that can deal with LOTS of situations go for the Pentax 18-135 (a trip, vacations, unknown weather). If you want a more specialized lens for higher quality photos, especially anything you would consider important (weddings, portraits, baby pictures) then the Sigma 17-70 is what you want. Best way I can describe it, when I'm just going out with the family the Pentax 18-135 gives me all the quality I need with lots of versatility. When I need the very best pictures I begin with the Sigma 17-70 and finish with my prime lenses.

normhead · 05-26-2015, 10:14 AM

Originally posted by aldorp

I own both the new Sigma 17-70 and Pentax 18-135 and I use them in very different ways.

In my house we call the Pentax 18-135 "Jack of All trades and Master of None". This is the lens I take when I have no idea what to expect and have little desire (or capability) of changing lenses on the go. I own 11 or 12 Pentax lenses and I can beat EVERY SINGLE focal length and aperture setting of the Pentax 18-135 with another lens I own. On the other hand it takes me 2 or 3 lenses to cover everything this lens does. So this lens is amazing for it's flexibility but not for it's optical quality. Having said that it has good center sharpness and from 18 - 100mm it has acceptable borders if you close it one or two stops. That this lens is weather seal is good too and adds to the versatility factor of the lens. I once had to do an outdoors wedding with this lens (It rained on that wedding, this was one of the few WR lenses I had on me) and it did not disappoint so please understand that this is not a bad lens. I just have better glass, especially if I bring out my primes and for quality this lens would never be my first choice.

The Sigma 17-70 is a TOTALLY different beast (regardless of what the reviews on this site say). This lens has great center at 17mm wide open with terrible border sharpness.This weakness can be minimized at f5.6 or f8.0 but is never fully solved at 17mm. This is NOT a great wide angle lens (and neither is the Pentax 18-135 for that matter). From 24mm to 70mm this lens kicks ass and starts taking down names. Very sharp wide open and gets better closing one stop at both center and borders. From 50mm to 70mm it is AMAZING wide open (f4.0) and perfect for portraits and what I use use it most often. This lens can show you what a Pentax is truly capable off doing. The macro capabilities of this lens is also very good for close up photography (not a true macro, macro is at least 1:1) and the lens is faster overall than the Pentax 18-135, but of course the Pentax reaches farther.

Having said that both lenses have something that is VERY important these days; good auto-focus performance for both speed and accuracy. Truth be told it does not matter how good a lens is, if it can't focus properly it is no better than a kit lens. Both lenses have very good track records in getting the shoots I want.

So if you want a very versatile lens that can deal with LOTS of situations go for the Pentax 18-135 (a trip, vacations, unknown weather). If you want a more specialized lens for higher quality photos, especially anything you would consider important (weddings, portraits, baby pictures) then the Sigma 17-70 is what you want. Best way I can describe it, when I'm just going out with the family the Pentax 18-135 gives me all the quality I need with lots of versatility. When I need the very best pictures I begin with the Sigma 17-70 and finish with my prime lenses.

+1 ^ Nothing in this post sounds off to me. I'd be happy to tack that one the bottom of my post.... sometimes "collective wisdom" really works.

reeftool · 05-26-2015, 10:41 AM

I have owned the Sigma 17-70c for about a year and a half and I can heartily recommend it. It performs well indoors and in low light. I'm using it on a K5. I find the 17-70 range very useful for my needs. I considered the 18-135 at the time but the Sigma was almost $100 cheaper so that influenced my decision also. No regrets whatsoever! I have shot 2 weddings with it along with just about everything else. It's pretty much always on my camera. Now, there is also new DA 16-85 in the mix to consider. The one drawback to the Sigma is that it's not weather sealed. It hasn't been a issue with me as it's pretty easy to protect your gear in foul weather.

If I was shopping today, I would be looking at the Sigma and the 16-85 as my choices and would likely go with the Sigma because of the price is pretty good.

05-26-2015, 06:34 AM	#1
aproud1 New Member Join Date: Oct 2008 Location: Good ol' Cincy Photos: Albums Posts: 23	Sigma 17-70 or Pentax 18-135 for my K50 All set to dive back into Pentax DSLR world. Unfortunately sold all of my lenses with my K10D. I'm pretty set on the K50 (size, price and performance) And want to get the best lens I can for my needs. Looking at two options being about the same price: 1. K50 Kit with 18-135 WR, And Pentax DA50 1.8 2. K50 with new Sigma 17-70 I like taking close up and landscape pics. The only real portrait type pictures are typically bass guitars. Also do a lot of indoor shots. So how does the 17-70 do indoors? Option one seems like the best deal but the Sigma looks like a really great lens. I figure I could use it until I can afford more lenses down the road. Depending on how it does in lower light. Thanks for any advice! Andy

05-26-2015, 07:02 AM - 1 Like	#3
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Sigma 17-70 2.8 - 4.5 Pentax 18-135 3.5-5.6 For indoor shooting the Sigma is only about a half stop faster, that's probably not going to make any difference very often. The 18-135, is clearly the most versatile. The arguments on these two are endless. I've never seen anyone with an 18-135 convince a Sigma 17-70 owner to switch. I've never seen a Sigma 17-70 owner convince an 18-135 owner to switch. The arguments either way are not terribly convincing. That being said I've seen a lot more excellent images produced by the 18-135, but then, a lot more people own it as far as I can tell, so that's not the best. In cases like this I usually go with the lens that's made by Pentax. There are advantages in lens identification in my software etc by staying with Pentax gear. For landscape the DA18-135 works fine unless you go over 50mm, at 135 it still has excellent centre sharpness for pseudo macro images. The 17-70m is sharper edge to edge from 50-70mm, but still falls behind in centre sharpness. I wouldn't give up the 70-135 end of the 18-135. But lots of people will be arguing that they don't use it. So you just need to figure out what kind of shooter you are. Forget the "17-70 has better IQ argument. it's nonsense based on very minor differences. The Sigma 17-70 is more consistent edge to edge, the 18-135 is better for centre sharpness. These are two different lenses, but, from 24mm to 35mm you won't see a lot of difference between them centre or border. Some guy deciding one of these lenses is better than the other, is simply stating his or her personal shooting preference, if you don't shoot his/her style, their analysis won't apply to you. http://www.photozone.de/Reviews/312-sigma-af-17-70mm-f28-45-dc-macro-test-report--review http://www.photozone.de/pentax/597-pentax_18135_3556?start=1 I shoot a lot of images from 50-135 where centre sharpness is more important than edge sharpness, so i like the 18-135, and at 24 mm the 18-135 is right up there with the best lenses on K-mount, as a landscape len, excellent centre and edge.. If I were to pick a point at which the 17-170 really shines it would probably for 40mm edge to edge. But I have a 40 XS prime that's better than both of them and is ƒ2.8, and is quite cheap. My 18-135 slideshow. Last edited by normhead; 05-26-2015 at 07:45 AM.*

05-26-2015, 09:23 AM	#10
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	I have lots of images using the 18-135 as a pseudo macro.... IN fact, the superior centre sharpness of the 18-135 makes it almost a perfect macro lens, unless you're photographing microchips. DA 18-135 pseudo macro slideshow. I have a SIgma 18-250 and 70-300 both labeled macro which don't do as good a job as the 18-135. My Sigma 70 macro though.. now that is a macro lens. Sigma plays a little looser with the term macro than Pentax does. 1:2, is good enough for Sigma, 1:1 seems to be the norm for Pentax. Last edited by normhead; 05-26-2015 at 09:39 AM.

05-26-2015, 10:02 AM - 4 Likes	#13
aldorp New Member Join Date: Dec 2014 Posts: 9	Depends what you want I own both the new Sigma 17-70 and Pentax 18-135 and I use them in very different ways. In my house we call the Pentax 18-135 "Jack of All trades and Master of None". This is the lens I take when I have no idea what to expect and have little desire (or capability) of changing lenses on the go. I own 11 or 12 Pentax lenses and I can beat EVERY SINGLE focal length and aperture setting of the Pentax 18-135 with another lens I own. On the other hand it takes me 2 or 3 lenses to cover everything this lens does. So this lens is amazing for it's flexibility but not for it's optical quality. Having said that it has good center sharpness and from 18 - 100mm it has acceptable borders if you close it one or two stops. That this lens is weather seal is good too and adds to the versatility factor of the lens. I once had to do an outdoors wedding with this lens (It rained on that wedding, this was one of the few WR lenses I had on me) and it did not disappoint so please understand that this is not a bad lens. I just have better glass, especially if I bring out my primes and for quality this lens would never be my first choice. The Sigma 17-70 is a TOTALLY different beast (regardless of what the reviews on this site say). This lens has great center at 17mm wide open with terrible border sharpness.This weakness can be minimized at f5.6 or f8.0 but is never fully solved at 17mm. This is NOT a great wide angle lens (and neither is the Pentax 18-135 for that matter). From 24mm to 70mm this lens kicks ass and starts taking down names. Very sharp wide open and gets better closing one stop at both center and borders. From 50mm to 70mm it is AMAZING wide open (f4.0) and perfect for portraits and what I use use it most often. This lens can show you what a Pentax is truly capable off doing. The macro capabilities of this lens is also very good for close up photography (not a true macro, macro is at least 1:1) and the lens is faster overall than the Pentax 18-135, but of course the Pentax reaches farther. Having said that both lenses have something that is VERY important these days; good auto-focus performance for both speed and accuracy. Truth be told it does not matter how good a lens is, if it can't focus properly it is no better than a kit lens. Both lenses have very good track records in getting the shoots I want. So if you want a very versatile lens that can deal with LOTS of situations go for the Pentax 18-135 (a trip, vacations, unknown weather). If you want a more specialized lens for higher quality photos, especially anything you would consider important (weddings, portraits, baby pictures) then the Sigma 17-70 is what you want. Best way I can describe it, when I'm just going out with the family the Pentax 18-135 gives me all the quality I need with lots of versatility. When I need the very best pictures I begin with the Sigma 17-70 and finish with my prime lenses.

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05-26-2015, 07:02 AM	#2
sterretje Veteran Member Join Date: Dec 2008 Location: Roodepoort, South Africa Photos: Gallery \| Albums Posts: 3,561	PF posted a review of the 17-70 contemporary. Conclusion is that it is superior to the 18-135 from an IQ perspective. https://www.pentaxforums.com/reviews/sigma-17-70mm-f28-4-contemporary/conclusion.html I assume it's also faster over the whole range which is beneficial for indoors. Only WR snd/or the extra reach are in favor of the 18-135. If you don't take cost into account, I would opt for the 17-70.

05-26-2015, 08:00 AM	#4
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	If I were starting out in the Pentax world today, I would get the 18-135 and DA 50 kit. (Did I read that right? They're offering both together? Or are you getting the 50 with what's left over if you don't get the Sigma?) IMO the extra reach and WR capability is worth a small loss in image quality and raw speed on your primary zoom lens. And having the DA 50 as well will put you in a good place for portrait and low-light or narrow-DOF work. I have the DA 50 and it's lovely. I admittedly don't have the 18-135, but I know what I'd be doing in your shoes.

05-26-2015, 08:04 AM	#5
HYS Veteran Member Join Date: Mar 2013 Photos: Gallery Posts: 377	But it seems that 18-135 is discontinued.

05-26-2015, 08:13 AM	#6
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by HYS But it seems that 18-135 is discontinued. Someone forgot to tell Pentax Canada smc PENTAX-DA 18-135mm F3.5-5.6 ED AL[IF] DC WR?Lenses?RICOH IMAGING CANADA Or Henry's PENTAX DA 18-135MM F3.5-5.6 ED WR 21977 Or B&H Pentax SMC DA 18-135mm F/3.5-5.6 ED AL (IF) DC WR Lens 21977 B&H But apparently there is some reliable source somewhere who knows more than suppliers and vendors. not

05-26-2015, 08:17 AM	#7
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	"Discontinued" and "There are no more available anywhere" are two very different things.

05-26-2015, 08:53 AM	#8
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by pathdoc "Discontinued" and "There are no more available anywhere" are two very different things. The same thing happened to a couple of lenses when they stopped the old production lines and updated them for HD coatings.

05-26-2015, 09:11 AM - 1 Like	#9
iss2012 Junior Member Join Date: May 2015 Location: Paris Photos: Albums Posts: 49	I have the 17-70 and for me it is very good for landscape (wide angle) and portrait (70 is nice). A detail that can make the difference is the "macro" (which is not real macro, but close to) feature that sigma has, you said that you want close up pictures so this feature is maybe what makes the difference between the two lenses. For the additional reach of the 18-135 you have to figure out if you will really need it or not. For me, 17-70 is a very versatile lense and perfect to begin with. some shots I took with are in my flickr if interested https://www.flickr.com/photos/117312932@N02/

05-26-2015, 09:43 AM	#11
MPrince Veteran Member Join Date: Sep 2006 Location: WV Posts: 1,495	Originally posted by normhead I've never seen anyone with an 18-135 convince a Sigma 17-70 owner to switch. I've never seen a Sigma 17-70 owner convince an 18-135 owner to switch. I've convinced a 17-70 owner to switch to the 18-135. The 17-70 owner I convinced to switch was...me!

05-26-2015, 09:58 AM	#12
iss2012 Junior Member Join Date: May 2015 Location: Paris Photos: Albums Posts: 49	Originally posted by MPrince I've convinced a 17-70 owner to switch to the 18-135. The 17-70 owner I convinced to switch was...me! Could you develop more the reasons behind ? Maybe you could add me to the converted list

05-26-2015, 10:14 AM	#14
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by aldorp I own both the new Sigma 17-70 and Pentax 18-135 and I use them in very different ways. In my house we call the Pentax 18-135 "Jack of All trades and Master of None". This is the lens I take when I have no idea what to expect and have little desire (or capability) of changing lenses on the go. I own 11 or 12 Pentax lenses and I can beat EVERY SINGLE focal length and aperture setting of the Pentax 18-135 with another lens I own. On the other hand it takes me 2 or 3 lenses to cover everything this lens does. So this lens is amazing for it's flexibility but not for it's optical quality. Having said that it has good center sharpness and from 18 - 100mm it has acceptable borders if you close it one or two stops. That this lens is weather seal is good too and adds to the versatility factor of the lens. I once had to do an outdoors wedding with this lens (It rained on that wedding, this was one of the few WR lenses I had on me) and it did not disappoint so please understand that this is not a bad lens. I just have better glass, especially if I bring out my primes and for quality this lens would never be my first choice. The Sigma 17-70 is a TOTALLY different beast (regardless of what the reviews on this site say). This lens has great center at 17mm wide open with terrible border sharpness.This weakness can be minimized at f5.6 or f8.0 but is never fully solved at 17mm. This is NOT a great wide angle lens (and neither is the Pentax 18-135 for that matter). From 24mm to 70mm this lens kicks ass and starts taking down names. Very sharp wide open and gets better closing one stop at both center and borders. From 50mm to 70mm it is AMAZING wide open (f4.0) and perfect for portraits and what I use use it most often. This lens can show you what a Pentax is truly capable off doing. The macro capabilities of this lens is also very good for close up photography (not a true macro, macro is at least 1:1) and the lens is faster overall than the Pentax 18-135, but of course the Pentax reaches farther. Having said that both lenses have something that is VERY important these days; good auto-focus performance for both speed and accuracy. Truth be told it does not matter how good a lens is, if it can't focus properly it is no better than a kit lens. Both lenses have very good track records in getting the shoots I want. So if you want a very versatile lens that can deal with LOTS of situations go for the Pentax 18-135 (a trip, vacations, unknown weather). If you want a more specialized lens for higher quality photos, especially anything you would consider important (weddings, portraits, baby pictures) then the Sigma 17-70 is what you want. Best way I can describe it, when I'm just going out with the family the Pentax 18-135 gives me all the quality I need with lots of versatility. When I need the very best pictures I begin with the Sigma 17-70 and finish with my prime lenses. +1 ^ Nothing in this post sounds off to me. I'd be happy to tack that one the bottom of my post.... sometimes "collective wisdom" really works.

05-26-2015, 10:41 AM	#15
reeftool Pentaxian Join Date: Dec 2007 Location: Upstate New York Photos: Gallery \| Albums Posts: 9,554	I have owned the Sigma 17-70c for about a year and a half and I can heartily recommend it. It performs well indoors and in low light. I'm using it on a K5. I find the 17-70 range very useful for my needs. I considered the 18-135 at the time but the Sigma was almost $100 cheaper so that influenced my decision also. No regrets whatsoever! I have shot 2 weddings with it along with just about everything else. It's pretty much always on my camera. Now, there is also new DA 16-85 in the mix to consider. The one drawback to the Sigma is that it's not weather sealed. It hasn't been a issue with me as it's pretty easy to protect your gear in foul weather. If I was shopping today, I would be looking at the Sigma and the 16-85 as my choices and would likely go with the Sigma because of the price is pretty good.