Which lens next? Pentax 15mm f/4 or Sigma 10-20mm f/3.5?

**frogoutofwater** · 11-19-2013, 08:54 AM

As I've indicated in my recent posts, I'm a new Pentaxian and I'm starting to accumulate lenses either for myself or to share with my husband. (I have the K-3. He has the K-30.) I'm significantly more into photography as a hobby than he is, and I certainly have a worse case of LBA than he does. (He is very much of the "Do we need it? Can we really afford it?" school of shopping.) These are the lenses we currently have:
- Pentax 18-55 kit lens (his lens, not used very much now)
- Sigma 18-250 (his main walk-around lens)
- Tamron 90mm f/2.8 macro
- Pentax 18-135 kit lens (my main walk-around lens)
- Pentax 50mm f/1.8 lens

We both tend to do a fair bit of street photography (NYC is such a wonderful show). I also do a lot of portrait photography (people and pets), and do some macro - I feel I've got things fairly well covered in that regard with our existing lens array (with the 50mm f/1.8 and the 90 mm f/2.8). He is a mountain climber and likes to do landscape/cityscaple photography. I'd like to explore the potential of a wide angle lens more (up until this point 18mm is the widest angle lens I've shot with, either on my Sony NEX or the Pentax). So, in connection with Black Friday/Cyber Monday, I'm on the lookout for a wide angle lens of some kind, either a wide angle zoom or a prime. Having read the reviews on this forum of the various wide-angle zooms, I think I've narrowed down my choice to the Sigma 10-20 f/3.5 (although a really good deal on an alternative lens in this range might tip the balance in another direction). But I'm also considering the 15mm f/4.

A couple of other factors that might be relevant to the choice: 1) Weight/size is a bit of a factor. From his perspective, if he's climbing, he wants to carry as little as possible (so a smaller/lighter prime has its advantages). Weight is also a big issue for me, as I have some back/neck trouble as well as a problem with one of my hands (severed tendon in a finger means that my hands can cramp up a bit when I hold a heavy camera for a long time.) 2) However, the 15mm only increases our range a bit beyond what w can already do with the 18-250 and the 18-135. He's probably a little less sensitive than I am to the difference in image quality that a prime (versus a zoom) can provide. 3) I'm not sure how significant a difference the max aperture (3.5 versus 4) makes, but we did notice recently that very little bit counts when you're trying to photograph street scenes at dusk.

Price isn't really an issue in terms of choosing between the two lenses (except that I'm always interested in good value and a good deal).

I am leaning toward the 10-20 zoom for the reasons above, but would love to hear a contrary recommendation and reasons. Thanks!

**jimr-pdx** · 11-19-2013, 09:19 AM

Originally posted by frogoutofwater

2) However, the 15mm only increases our range a bit beyond what w can already do with the 18-250 and the 18-135

You'll be surprised how much different the 15 is from the 18; I went to the 16-45 and found those two extra mm to be quite significant!

Other than that I've nothing to add, haven't used your two best choices nor do I street-shoot. Good luck with your decision!

**blackcloudbrew** · 11-19-2013, 09:37 AM

Every 1 mm below about 24mm is quite a step in image difference. In reading your needs, I think the DA15 would be best. It is just an amazing lens with special pixy dust in it that makes every image better (I'm not really kidding about that either)! The Sigma 10-20 is very good too but you can't beat the DA15 for size, weight, and that special something it has.

here is another tread on exactly this issue:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/197044-tryi...0-4-5-6-a.html

or this very very very long thread
https://www.pentaxforums.com/forums/122-lens-clubs/86234-15mm-limited-controls-my-mind-club.html

sterretje · 11-19-2013, 10:36 AM - **1 Like**

This might help to visualize the focal lengths: Focal length comparison tool, Tamron USA

I'm not very convinced of UWAs for landscapes (just personal). For cityscapes and architecture, I would prefer the flexibilty (range of focal lengths) that a zoom offers (Sigma 10-20 or 12-24 or Pentax 12-24). It's the only lens that's lacking in my collection, so no advice from that perspective.

normhead · 11-19-2013, 10:39 AM

Just to be a smart ass…. Sigma 8-16.
https://www.pentaxforums.com/forums/122-lens-clubs/107938-sigma-8-16mm-club-16.html

After a long trip down this road, that's where I ended up.

**frogoutofwater** · 11-19-2013, 10:44 AM

Thanks for the link to the earlier thread (sorry, I should have searched for it first). There are some compelling arguments made there and in the replies to my thread for the 15mm. It does sound like the 15mm would suit my husband (at least) better for his mountain-climbing trips - lighter, less flare, etc.

jimt · 11-19-2013, 12:09 PM

I have both the Sigma 10-20 3.5 and the 15ltd
I find that walking around the city, hiking, fishing etc. the 15ltd is a nicer package and weight.
I purchased the 15ltd after having the Sigma, and haven't used the Sigma much since.
For walking around the city, I usually have one of the Ltd primes on the camera and at least one more tucked into a pocket.

**frogoutofwater** · 11-19-2013, 12:29 PM

Originally posted by jimt

I have both the Sigma 10-20 3.5 and the 15ltd
I find that walking around the city, hiking, fishing etc. the 15ltd is a nicer package and weight.
I purchased the 15ltd after having the Sigma, and haven't used the Sigma much since.
For walking around the city, I usually have one of the Ltd primes on the camera and at least one more tucked into a pocket.

I should add, by the way, that the mountains my husband (and long-time ACC member) loves to climb and photograph are the Rockies. And by that I mean the Canadian Rockies (we're expats in NYC). Our cats are named Jasper, Louise, Robson and Andromeda

MichaelP · 11-19-2013, 01:57 PM

I have the Sigma 10-20 F4-5.6 which is considerably lighter that the f3.5 (and quite a bit cheaper in the UK) but my fav. "walk about" lens is a recent purchased second hand 16-45 f4. Primes, like the 15ltd are almost always sharper but, obviously, less versatile than zooms. But we can get too fixated on sharpness above all else: I have rejected few images for being not sharp enough but plenty that were just poor shots. Finally, the Sigma is great but - as most Pentax users will tell you - most other brands cannot match the Pentax colours and contrast and I spend more time fussing over the colours of the Sigma images than anything else. Reading that back it doesn't seem all that much help to you now! whatever you get use it and enjoy what it does.

Kozlok · 11-19-2013, 04:25 PM

The right answer (at least for me!) is the 15 and the DA10-17 fisheye. That's the lens for when wide just isn't wide enough!

**Sandy Hancock** · 11-19-2013, 04:35 PM

Like Kozlok, I have the DA15 and DA10-17 (and the DA*16-50), and feel no need to expand my wide options.
15mm is appreciably wider than your kit zooms, and the qualities of the images which come from it are pretty special. It is also tiny compared to everything other option.
The fisheye zoom is great for the situations when merely ultra-wide is not enough. A 10mm rectilinear lens (like the Sigma) has nowhere near the field of view of a 10mm fisheye.

11-19-2013, 08:54 AM	#1
frogoutofwater Site Supporter Join Date: Oct 2013 Location: Homesick Canadian in New York City Photos: Gallery Posts: 658	Which lens next? Pentax 15mm f/4 or Sigma 10-20mm f/3.5? As I've indicated in my recent posts, I'm a new Pentaxian and I'm starting to accumulate lenses either for myself or to share with my husband. (I have the K-3. He has the K-30.) I'm significantly more into photography as a hobby than he is, and I certainly have a worse case of LBA than he does. (He is very much of the "Do we need it? Can we really afford it?" school of shopping.) These are the lenses we currently have: - Pentax 18-55 kit lens (his lens, not used very much now) - Sigma 18-250 (his main walk-around lens) - Tamron 90mm f/2.8 macro - Pentax 18-135 kit lens (my main walk-around lens) - Pentax 50mm f/1.8 lens We both tend to do a fair bit of street photography (NYC is such a wonderful show). I also do a lot of portrait photography (people and pets), and do some macro - I feel I've got things fairly well covered in that regard with our existing lens array (with the 50mm f/1.8 and the 90 mm f/2.8). He is a mountain climber and likes to do landscape/cityscaple photography. I'd like to explore the potential of a wide angle lens more (up until this point 18mm is the widest angle lens I've shot with, either on my Sony NEX or the Pentax). So, in connection with Black Friday/Cyber Monday, I'm on the lookout for a wide angle lens of some kind, either a wide angle zoom or a prime. Having read the reviews on this forum of the various wide-angle zooms, I think I've narrowed down my choice to the Sigma 10-20 f/3.5 (although a really good deal on an alternative lens in this range might tip the balance in another direction). But I'm also considering the 15mm f/4. A couple of other factors that might be relevant to the choice: 1) Weight/size is a bit of a factor. From his perspective, if he's climbing, he wants to carry as little as possible (so a smaller/lighter prime has its advantages). Weight is also a big issue for me, as I have some back/neck trouble as well as a problem with one of my hands (severed tendon in a finger means that my hands can cramp up a bit when I hold a heavy camera for a long time.) 2) However, the 15mm only increases our range a bit beyond what w can already do with the 18-250 and the 18-135. He's probably a little less sensitive than I am to the difference in image quality that a prime (versus a zoom) can provide. 3) I'm not sure how significant a difference the max aperture (3.5 versus 4) makes, but we did notice recently that very little bit counts when you're trying to photograph street scenes at dusk. Price isn't really an issue in terms of choosing between the two lenses (except that I'm always interested in good value and a good deal). I am leaning toward the 10-20 zoom for the reasons above, but would love to hear a contrary recommendation and reasons. Thanks!

11-19-2013, 09:37 AM	#3
blackcloudbrew Loyal Site Supporter Join Date: Mar 2009 Location: Cotati, California USA Photos: Gallery \| Albums Posts: 3,784	Every 1 mm below about 24mm is quite a step in image difference. In reading your needs, I think the DA15 would be best. It is just an amazing lens with special pixy dust in it that makes every image better (I'm not really kidding about that either)! The Sigma 10-20 is very good too but you can't beat the DA15 for size, weight, and that special something it has. here is another tread on exactly this issue: https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/197044-tryi...0-4-5-6-a.html or this very very very long thread https://www.pentaxforums.com/forums/122-lens-clubs/86234-15mm-limited-controls-my-mind-club.html Last edited by blackcloudbrew; 11-19-2013 at 09:44 AM.

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11-19-2013, 09:19 AM	#2
jimr-pdx Site Supporter Join Date: May 2010 Location: 1hr north of PDX Photos: Gallery \| Albums Posts: 3,515	Originally posted by frogoutofwater 2) However, the 15mm only increases our range a bit beyond what w can already do with the 18-250 and the 18-135 You'll be surprised how much different the 15 is from the 18; I went to the 16-45 and found those two extra mm to be quite significant! Other than that I've nothing to add, haven't used your two best choices nor do I street-shoot. Good luck with your decision!

11-19-2013, 10:36 AM - 1 Like	#4
sterretje Veteran Member Join Date: Dec 2008 Location: Roodepoort, South Africa Photos: Gallery \| Albums Posts: 3,534	This might help to visualize the focal lengths: Focal length comparison tool, Tamron USA I'm not very convinced of UWAs for landscapes (just personal). For cityscapes and architecture, I would prefer the flexibilty (range of focal lengths) that a zoom offers (Sigma 10-20 or 12-24 or Pentax 12-24). It's the only lens that's lacking in my collection, so no advice from that perspective.

11-19-2013, 10:39 AM	#5
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 24,678	Just to be a smart ass…. Sigma 8-16. https://www.pentaxforums.com/forums/122-lens-clubs/107938-sigma-8-16mm-club-16.html After a long trip down this road, that's where I ended up.

11-19-2013, 10:44 AM	#6
frogoutofwater Site Supporter Join Date: Oct 2013 Location: Homesick Canadian in New York City Photos: Gallery Posts: 658 Original Poster	Thanks for the link to the earlier thread (sorry, I should have searched for it first). There are some compelling arguments made there and in the replies to my thread for the 15mm. It does sound like the 15mm would suit my husband (at least) better for his mountain-climbing trips - lighter, less flare, etc.

11-19-2013, 12:09 PM	#7
jimt Junior Member Join Date: Oct 2012 Location: North of 49, west of 106 Posts: 30	I have both the Sigma 10-20 3.5 and the 15ltd I find that walking around the city, hiking, fishing etc. the 15ltd is a nicer package and weight. I purchased the 15ltd after having the Sigma, and haven't used the Sigma much since. For walking around the city, I usually have one of the Ltd primes on the camera and at least one more tucked into a pocket.

11-19-2013, 12:29 PM	#8
frogoutofwater Site Supporter Join Date: Oct 2013 Location: Homesick Canadian in New York City Photos: Gallery Posts: 658 Original Poster	Originally posted by jimt I have both the Sigma 10-20 3.5 and the 15ltd I find that walking around the city, hiking, fishing etc. the 15ltd is a nicer package and weight. I purchased the 15ltd after having the Sigma, and haven't used the Sigma much since. For walking around the city, I usually have one of the Ltd primes on the camera and at least one more tucked into a pocket. I should add, by the way, that the mountains my husband (and long-time ACC member) loves to climb and photograph are the Rockies. And by that I mean the Canadian Rockies (we're expats in NYC). Our cats are named Jasper, Louise, Robson and Andromeda

11-19-2013, 01:57 PM	#9
MichaelP Inactive Account Join Date: Nov 2013 Posts: 3	I have the Sigma 10-20 F4-5.6 which is considerably lighter that the f3.5 (and quite a bit cheaper in the UK) but my fav. "walk about" lens is a recent purchased second hand 16-45 f4. Primes, like the 15ltd are almost always sharper but, obviously, less versatile than zooms. But we can get too fixated on sharpness above all else: I have rejected few images for being not sharp enough but plenty that were just poor shots. Finally, the Sigma is great but - as most Pentax users will tell you - most other brands cannot match the Pentax colours and contrast and I spend more time fussing over the colours of the Sigma images than anything else. Reading that back it doesn't seem all that much help to you now! whatever you get use it and enjoy what it does.

11-19-2013, 04:25 PM	#10
Kozlok Pentaxian Join Date: Jun 2012 Location: Albuquerque Photos: Gallery Posts: 1,741	The right answer (at least for me!) is the 15 and the DA10-17 fisheye. That's the lens for when wide just isn't wide enough!

11-19-2013, 04:35 PM	#11
Sandy Hancock Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 5,433	Like Kozlok, I have the DA15 and DA10-17 (and the DA*16-50), and feel no need to expand my wide options. 15mm is appreciably wider than your kit zooms, and the qualities of the images which come from it are pretty special. It is also tiny compared to everything other option. The fisheye zoom is great for the situations when merely ultra-wide is not enough. A 10mm rectilinear lens (like the Sigma) has nowhere near the field of view of a 10mm fisheye.