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01-05-2014, 11:33 AM   #1
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Sigma 17-70mm Contemporary vs. kit lens @ the wide end, f8 ?

The new "Contemporary" 17-70mm zoom seems to be the right lens for my travel needs. So far I've used my copy of the kit lens, which is pretty sharp, except at 18-20mm, where I tend to take about 25% of my shots. The kit lens' borders in this range aren't bad, but they show some bothersome softness even after correction in DxO. (My copy of the DA 18-55mm also shows a bit of decentering at the wide end, while being great from 24mm to 55mm.)

The Sigma is light, has good range, good build, nice colors; appears to be very sharp; DxO supports it with my K-30. However, quite a few reviews I've read complain about border softness at the wide end. (Some say the Sigma 17-50mm is better in this regard; others say the 17-70 Contemporary only seems to be softer at the borders because it is so much sharper in the center...) Anyway, my question to anyone who uses the Sig 17-70 C is: can you notice a significant improvement at the borders in the 17-24mm range, by comparison to the kit lens (esp. at f7-9)? Thank you!


Last edited by causey; 01-05-2014 at 11:44 AM.
01-05-2014, 04:25 PM   #2
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You sound like someone ready to step into the limited primes! For the price of that 17-70, you could get a used 21, and almost enough left over for a used 40. Eat some mac and cheese for a month, and you could add the 15 in short order.
01-05-2014, 05:37 PM   #3
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I have a 40mm ltd. and a Samyang 14mm. I was considering buying a 21mm ltd., but a zoom is much more practical in many situations... I visited Petra, in Jordan, a month ago--lots of dust, impossible to change lenses there. I had to use the kit lens.
01-05-2014, 08:02 PM   #4
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For dust (or rain), choose the 18-135. It is pretty terrible in the corners wide open, but the range is dynamite, and the pictures have a really nice look to them. Everything I have ever seen says the Sigma 17-70 is just a bit nicer at every FL, but my 18-135 is my "with the family" lens. I take that and my Sigma 30 for indoor work, and I only change lenses going from outside to inside. One thing that seems clear to me, the early review samples are worse in the corners than what I get. It is soft in the corners, no doubt, but it's very workable for me when I don't want to mess with primes.

Here's some of my favs with the 18-135.









01-05-2014, 08:14 PM   #5
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Thank you, but I'm interested in the Sigma. Faster, sharper... Very nice pics, though And the DA 18-135mm has excellent, ltd-like microcontrast.

Last edited by causey; 01-05-2014 at 08:30 PM.
01-06-2014, 10:58 AM - 1 Like   #6
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I don't shoot many photos from 17-24mm, unfortunately. When I do, there's rarely anything interesting in the corners. It's the worst part of the lens for distortion, although anything north of 20mm is pretty problem free. I find that it's pretty easy to get into the best part of the lens (30-40mm) by moving back a bit, which also allows you to get closer to hyperfocal distance for landscape shots.

Click on the photos to open the full-sized versions. Some may not be that great because I only venture into this focal range when I have no choice (for max sharpness, 35mm is the sweet spot). Try to draw the comparison across the frame.

These are probably some of my least interesting photographs. As I said, I only venture into this range when the other option is to not take the photo. All of these photos were shot with the K-5 IIs.

Here's some shot with the Sigma:

Minute Man NHP: 23mm, f/6.3, 1/100s, ISO160


Inside buildings at Greenfield Village:

17mm, f/5.6, 1/80s, ISO1600


19mm, f/5,6, 1/80s, ISO2000


23mm, f/8, 1/100s, ISO100


Here's one in Madison, WI:

21mm, f/5.6, 1/320s, ISO100



Here are some with the kit lens, 18-55mm f/3.5-5.6 II, all at Chaco Culture:

18mm, f/7.1, 1/250s, ISO100


18mm, f/5.6, 1/100s, ISO80


20mm, f/7.1, 1/160s, ISO80


21mm, f/8.0, 1/250s, ISO100


24mm, f/8.0, 1/200s, ISO100



You can see a significant roll-off in sharpness with the kit lens. You don't see nearly the same thing with the Sigma, although I don't have any photos in similar light to the kit lens photos. I'll let you be the judge.

I can't do a perfect comparison because I no longer have the kit lens in my possession. It was strapped to my old K110D and given away to a family member, after I upgraded to the K-5IIs and this Sigma.

Last edited by MadMathMind; 01-06-2014 at 11:26 AM.
01-06-2014, 11:55 AM   #7
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Thank you very much for these pics. Clearly, the Sigma is much better than the kit lens at the borders. There's no comparison. The lens is extremely sharp. (But does your copy front focus, or is it my impression that it does? In a few shots--the last two, for instance--the background seems to be out of focus.)

Last edited by causey; 01-06-2014 at 02:51 PM.
01-06-2014, 01:28 PM - 1 Like   #8
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First of all, I haven't tried the Sigma. But judging from the in-depth review here on PF, the pros and cons compared to the DA 18-135 (which I do have) could be:
- the Sigma is (a bit) wider and faster
- the Sigma has better corner sharpness in the wide end
- both have quite a bit of distortion in the wide end
- the Pentax is WR
- the Pentax has more reach (quite usable at 135 IMO)
- the Pentax is a bit smaller and lighter

If you only look at the optics I think the Sigma is the one. I bought the 18-135 mainly as my bad weather/all-in-one lens and use primes if I need anything better/faster. Works wonderfully for me

01-06-2014, 02:47 PM   #9
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I bought the Sigma on pre order and after having it for awhile now I no longer use my DA 18-55. My DA 18-55 is from 2006 and came with my K10D. I also upgraded to the new HD 55-300 WR for the additional reach. IQ with the K30 and these lenses suit me very well. I do use the wide end of the Sigma 17-70 C a lot.
01-06-2014, 02:49 PM   #10
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QuoteOriginally posted by savoche Quote
First of all, I haven't tried the Sigma. But judging from the in-depth review here on PF, the pros and cons compared to the DA 18-135 (which I do have) could be:
- the Sigma is (a bit) wider and faster
- the Sigma has better corner sharpness in the wide end
- both have quite a bit of distortion in the wide end
- the Pentax is WR
- the Pentax has more reach (quite usable at 135 IMO)
- the Pentax is a bit smaller and lighter

If you only look at the optics I think the Sigma is the one. I bought the 18-135 mainly as my bad weather/all-in-one lens and use primes if I need anything better/faster. Works wonderfully for me

Not looking only at the optics, although for me IQ comes first, but, as you noted, the Sigma is faster, wider, shaper than the Pentax 18-135mm. (Reviews indicate it is much sharper than the Pentax.) I don't care much about WR, since I don't like shooting in the rain, anyway. And for the kind of dust I may have to deal with the Sigma's robust build should be fine.

Last edited by causey; 01-06-2014 at 07:52 PM.
01-06-2014, 03:09 PM   #11
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QuoteOriginally posted by causey Quote
Thank you very much for these pics. Clearly, the Sigma is much better than the kit lens at the borders. There's no comparison. The lens is extremely sharp. (But does your copy front focus, or is it my impression that it does? In a few shots--the last two, for instance--the background seems to be out of focus.)
You mean the garden and the Wisconsin State Capitol? The garden I can see what you mean. I'd guess the house in that picture is 20-30 feet away, or so. At f/8 and 23mm, we should have almost complete DoF. I never really looked that closely at that picture, I guess.

The Capitol looks to be pretty good to me. I don't see anything sharper in the foreground than the back, unless my eyes aren't as good as yours.

Still, if there's some advice you can give for investigating front focus, I'd love to hear it!
01-06-2014, 03:25 PM   #12
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QuoteOriginally posted by MadMathMind Quote
You mean the garden and the Wisconsin State Capitol? The garden I can see what you mean. I'd guess the house in that picture is 20-30 feet away, or so. At f/8 and 23mm, we should have almost complete DoF. I never really looked that closely at that picture, I guess.

The Capitol looks to be pretty good to me. I don't see anything sharper in the foreground than the back, unless my eyes aren't as good as yours.

Still, if there's some advice you can give for investigating front focus, I'd love to hear it!
Sorry, my mistake... I should have clicked on the pics. They look different--much sharper, including the background--if clicked and opened in a separate page.
01-06-2014, 03:53 PM   #13
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Photozone has tests of the Pentax 18-55 and Sigma 17-70 non-contemporary on the Pentax-K category, as well as comparisons of the 17-70 old and the 17-70 contemporary. My sense is that their copy of the K-mount 17-70 was a bit of a dud, as the Nikon versions do not have as extreme a corner resolution dropoff near wide open (maybe incompatible microlenses or something?). The contemporary appears to be a modest improvement on the older version, but nothing earthshaking.

In terms of numbers, at f/8 the Sigma puts out 1814 LW/PH and the Pentax kit lens does 1484 LW/PH (22% more resolution). Add 5% for the new Contemporary design at f/8 (according to the Nikon comparison), giving 1905 LW/PH. In comparison the Pentax 12-24mm puts out 1936 LW/PH at this setting, and puts out 1910 LW/PH right from wide open instead of the 1450 of the Pentax and the 1038 of the Sigma (regardless of the cause, pretty much garbage).

Overall I don't think the 17-70 will be that much better than the 18-55, if at all. Instead of trying to buy a superzoom that does what you want, what about buying a wider-angle prime or a wide-zoom instead? There are a lot of nice zooms around the 10-20mm range, and something like the Samyang 14mm is a cheap way to test whether you actually want to go wider. Remember that as long as you stand in the same place (identical perspective), cropping can always replicate using a longer focal length if you actually wanted 17mm instead of 14mm.

Last edited by Paul MaudDib; 01-06-2014 at 04:05 PM.
01-06-2014, 04:13 PM   #14
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QuoteOriginally posted by Paul MaudDib Quote
Photozone has tests of the Pentax 18-55 and Sigma 17-70 non-contemporary on the Pentax-K category, as well as comparisons of the 17-70 old and the 17-70 contemporary. My sense is that their copy of the K-mount 17-70 was a bit of a dud, as the Nikon versions do not have as extreme a corner resolution dropoff near wide open (maybe incompatible microlenses or something?). The contemporary appears to be a modest improvement on the older version, but nothing earthshaking.

In terms of numbers, at f/8 the Sigma puts out 1814 LW/PH and the Pentax kit lens does 1484 LW/PH (22% more resolution). Add 5% for the new Contemporary design at f/8 (according to the Nikon comparison), giving 1905 LW/PH. In comparison the Pentax 12-24mm puts out 1936 LW/PH at this setting, and puts out 1910 LW/PH right from wide open instead of the 1450 of the Pentax and the 1038 of the Sigma (regardless of the cause, pretty much garbage).

Overall I don't think the 17-70 will be that much better than the 18-55, if at all. Instead of trying to buy a superzoom that does what you want, what about buying a wider-angle prime or a wide-zoom instead? There are a lot of nice zooms around the 10-20mm range, and something like the Samyang 14mm is a cheap way to test whether you actually want to go wider. Remember that as long as you stand in the same place (identical perspective), cropping can always replicate using a longer focal length if you actually wanted 17mm instead of 14mm.
Thank you for your suggestions, Paul. I have the Samyang (Rokinon) 14mm, with which I am very satisfied. I tried the Sigma 10-20, and didn't like it. But I'm interested in this zoom for a few reasons I have after doing a lot of research. As I said, I'd like to have a sharp zoom for travel. I've done my homework, and I don't want any other zoom or prime lens. I have a nice set of primes which I'm going to complement with a DA 21mm at some point. Right now I'm interested in what users of the Sigma 17-70mm C have to say about this lens...

Last edited by causey; 01-07-2014 at 05:55 AM.
01-06-2014, 11:54 PM   #15
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QuoteOriginally posted by causey Quote
Thank you for your suggestions, Paul. I have the Samyang (Rokinon) 14mm, with which I am very satisfied. I tried the Sigma 10-20, and didn't like it. But I'm interested in this zoom for a few reasons I have after doing a lot of research. As I said, I'd like to have a sharp zoom for travel. I've done my homework, and I don't want any other zoom or prime lens. I have a nice set of primes which I'm going to complement with a DA 21mm at some point. But right now I'm interested in what users of the Sigma 17-70mm C have to say about this lens...
Sounds to me you should start looking for a good deal on the 17-70 C.

As you say, you've done your homework, you know what you want and need from the lens, and I think no one can doubt that the Sigma is a good lens - and better than the 18-135 in many respects. Of course, getting some more feedback from owners would always be good, but I think you've made your choice - and I think you've made the right one.
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