| Author: | | Pentaxian Registered: September, 2017 Location: South Wales Posts: 2,961 | | Review Date: April 10, 2024 | Recommended | Price: $200.00
| Rating: 9 |
| Pros: | Widest available zoom for FF, Well made. | | Cons: | Heavy, poor cap design. | | Sharpness: 8
Aberrations: 9
Bokeh: 4
Handling: 6
Value: 6
Camera Used: K-1
Autofocus: 8
New Or Used: Used
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This is one of the widest rectlinear lenses ever made for full frame in K-mount. It was introduced with the usual variety of mounts around 2003, but the K-mount version (KAF to be exact) seems to have been discontinued soon after because Pentax had no full frame camera in their roadmap at that time. Sigma did continue to offer an APS-C K-mount 10-20mm and later a 8-16mm HSM.
Consequently this lens is rare in K-mount, and I am surprised there are 12 reviews here already. When I bought this one (from Japan) there were only two on Ebay worldwide, and the other was three times this price; yet there were over twenty in other mounts at half the price, and plenty of K-mount APS-C 10-20mm. Another review calls it a budget choice, but for used it is not particularly budget and there are no equivalent lenses to choose from anyway, although Irix make an 11mm prime. There would be no good reason to buy this 12-24mm for an APS-C body, you would be much better off with the DC 10-20mm.
Don't even think about bokeh with a lens this wide - the Laws of Physics are against it, the depth of field is massive. I gave it a 4.
The build is of high quality and it suits the K-1 well. It is heavy though, and my kit of a K-1 with this, a Sigma 70-300mm of the same period, and the Pentax DFA 24-70mm, is quite a heft in a shoulder bag.
The lens has a fixed shallow petal hood, and others have mentioned the design failing with the cap. The cap slides on like with the old K-series shift lens and consists of two parts : a sleeve with the open front having an 82mm filter thread, and a conventional cap that clips into that thread. You could leave the sleeve in place and screw in an 82mm filter, but as others have said, if the sleeve is not removed, and even more so if there is a filter fitted to it, there will be vignetting at wider angles. I don't mind that a front filter cannot be used at wider angles because it would need to be the size of a tea plate to avoid vignetting, and if the lens body were designed for that it would be very cumbersome. However, the back end of the lens has provision to slide in a small gel filter, which you seem to be expected to cut to size yourself.
The sleeve of the cap is held on by friction, being felt lined. However on my copy the cap's hold is weak (it falls straight off if pointed downwards) so I don't walk around with it on the camera in case I lose it, but neither do I want to walk around without the cap because the lens bulges in a vulnerable way. So I put it back in the bag between shots. I might try replacing the felt to make it a firmer fit. Sigma should have incorporated some kind of bayonet catch to secure it. If you buy this lens, make sure it comes with at least the sleeve part of the cap because you would have a hard time finding another.
| | | | | | | New Member Registered: April, 2023 Location: Sunny Wisconsin Posts: 2
2 users found this helpful
| | Review Date: September 2, 2023 | Recommended | Price: $375.00
| Rating: 9 |
| Pros: | Incredibly wide angle, solid construction | | Cons: | Not as sharp as a prime, not able to take filters, weird lens cap. | | Sharpness: 8
Aberrations: 8
Bokeh: 7
Handling: 10
Value: 10
Camera Used: K-1ii, K-3
Autofocus: 9
New Or Used: Used
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This is an excellent budget choice for a super ultra-wide angle full-frame lens.
I have been coming back to this lens after just not getting enough wide angle from my Irix 15 2.4. I would say samples of this lens in good condition were hard to find at a reasonable price. Once KEH had a sale and had a copy under $400 it was time. For what this lens provides, I would consider this lens an Excellent value. There are relatively few good choices for Pentax full frame ultra wide and this lens is probably the best on a budget.
Although the 15-30 Pentax lens used is coming down in price, the extra on the 12-15 end is sweet. Definitely, the extra 15 or so degrees of angle is great. A few caveats, certainly not as sharp as the prime-length lenses that I have in this range, but that should be expected. When shooting at 12mm zooming in gives pretty decent results even at wide open, but best at f 8.0. Lines are reasonably straight and Photoshop/Lightroom has a profile to correct aberrations to give incredible results.
Comparing distortions and lines on the Sigma 10-20 3.5 on a K3, this lens produces similar results at the wide end on the respective camera. Not sure that this lens has much value on an APS camera.
The number one downfall is not having the ability to mount filters. It's part of the design and without some crazy super big bulky solution, you will have to work around that. The lens cap system has a learning curve as is the number two downfall. The cap mounts on a removable ring that can be used to hold filters but produces vignetting from 12-18mm. This cap holder has to be removed. The last thing to note, is that comparatively this lens is a fairly slow lens. At 4.5 on the fast end, this is the second slowest lens in my kit (second only to the Sigma 170-500 F5.0). I don't usually see a need for a fast but if you were shooting low light images (i.e. astro/night) might not give good results.
| | | | | New Member Registered: December, 2012 Posts: 16
2 users found this helpful
| | Review Date: October 7, 2019 | Recommended | Price: $350.00
| Rating: 8 |
| Pros: | 12 mm is great at ff | | Cons: | no simple filter system | | Sharpness: 8
Aberrations: 7
Bokeh: 5
Handling: 8
Value: 8
Camera Used: pentax k1
Autofocus: 8
New Or Used: Used
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Its a great lens, my choice por landscapes
 | | | | | Veteran Member Registered: February, 2009 Location: Edmonton Posts: 314
5 users found this helpful
| | Review Date: July 28, 2017 | Recommended | Price: $305.00
| Rating: 9 |
| Pros: | Very little distortion, vignetting, and CAs. It's sharp. | | Cons: | Flare! | | Sharpness: 9
Aberrations: 8
Bokeh: 6
Handling: 7
Value: 9
Camera Used: K-1
Autofocus: 6
New Or Used: 8
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As a long time user of Fisheye lenses, I often feel like the pictures have a more "real" looking perspective than a rectilinear wide angle such as this lens. The 180 degrees of a fisheye also don't feel so limited as the 122 degree field of view you get at 12mm on this Sigma 12-24. On the other hand, anybody who has not used a fisheye will be astounded by how wide 12mm is on a full frame camera - and won't feel limited at all.
However, with a fisheye, I've always been disappointed with most of my "defished" images when shooting subjects like interiors or architecture. The defishing process stretches and distorts the corners too much, which really doesn't look nice.
With all that in mind, I am principally comparing this lens to the DA 10-17 and F 17-28 Fisheyes that it competes with in my bag. 
Image quality is very good for the most part.. Wide open at 12mm (f/4.5) is probably the softest spot of the lens, but the subject in focus will still be sharp enough to please, with even a little bizarre bokeh if you're lucky:
The levels of CA and purple fringing are low and easily corrected in Lightroom. Lightroom also has a built-in profile for this lens to take care of the little vignetting and distortion that exists. Distortion at 12mm is not much, and really only needs to be corrected when you absolutely MUST have perfectly straight lines. The images still appear properly "rectilinear" to most people without correction.
Here is f/10, distortion corrected, vignetting uncorrected:
It's as sharp as either the 10-17 and 17-28 fisheyes (very!) so I'm quite pleased with that aspect.
Generally, I find it is best between f/8 and f/11 for most photos of landscapes or architecture. The corners sharpen up very well and CAs are reduced to a negligible level. I've also had good results without too much diffraction softening shooting at the smallest apertures to bring close foreground into focus, here is f/20 at 15mm:
12mm, f/11:
 by
14mm, f/11, some clouds cropped off the top:
So far so good, it's a good competitor to the fisheye lenses, except for one aspect...FLARE! You can point the 10-17 and 17-28 Fisheyes at the sun all day and on the rare occasion you do get flare, it is tiny and easily cloned out. This Sigma 12-24 is not even close to comparable, it's 16 elements and large bulbous front element produce very large, long, and complex flare patterns. I don't mind some dramatic flare on occasion, but this lens produces it too reliably.
Slightly artistic looking flare at 12mm, f/4.5:
f/10:
This one is further "enhanced" by tiny flecks of dust resting on the front element:
f/11:
Unless you're aim is to get wild flares like those, it's generally a good idea not to point this lens directly at the sun. The worst flare is visible in the viewfinder, so you just have to be mindful of where it's going to land. If you change your composition slightly, or mask the sun with some foreground object like a tree, you can still get good images:
In conclusion, I won't be selling my fisheyes, but I won't sell this lens either. Where the fisheye excels at flare resistance and rendering, the sigma wins for interiors and architecture if you're able to tame the sun.
As time passes, you will find more and more sample photos right here: Mock's images with Sigma 12-24 on K-1. | | | | | | | Loyal Site Supporter Registered: August, 2010 Location: Massachusetts Posts: 59,104
3 users found this helpful
| | Review Date: July 26, 2017 | Recommended | Price: None indicated
| Rating: 7 |
| Pros: | covers a really useful WA range, reasonably sized for what it does | | Cons: | I found the edge and corner rendering unsatisfactory | |
Found this on EBAY, from a camera store, apparently a brand-new unsold leftover from the 1990's. The WA range was really useful, and at the time of purchase there was no other 12mm rectilinear with FF coverage available in K-mount. Considering it's coverage, it's decently compact, smaller and lighter than the new Pentax 15~35mm (purchased one when I got the K1, but returned it as soon as I saw how YUGE and heavy it was - knew instantly it would be left at home too often). The 12-24 Siggy recorded many otherwise impossible to obtain images, but in many of them I found the edges and corners unacceptably soft and a bit "smeary." Subsequently I sold it to another Pentaxian, at a loss (=the rental price to use it on the Utah trip), and eventually purchased a Laowa/Venus 12mm which is a substantially better lens. I also purchased an Irix 15mm, also superior to the Sigma at that FL, but the Irix is really big, REALLY big IMHO and therefore not a good take-along lens for traveling. The 12mm Laowa is significantly smaller, similar in size to the Siggy
| | | | | Site Supporter Registered: December, 2010 Location: Colorado Front Range Posts: 644
2 users found this helpful
| | Review Date: October 26, 2016 | Recommended | Price: $450.00
| Rating: 8 |
| Pros: | wide angles, good geometry/low distortion | | Cons: | not the sharpest | |
I used to use this lens with a FF Sony a850, and I repurchased it when I got my K-1. It doesn't seem so sharp on my new camera. My Sigma 8-16 was much shaper on the K5IIs. The 12-24 is sharp near the center, but the edges aren't impressive by f8 (which, to be fair, may be only one stop down). This weakness is only visible when enlarging the image on a jumbo desktop screen, of course. I'd call the sharpness "adequate," but for landscapes and other enthusiast work, I'll be using my 12mm Zeiss Touit on the Fuji X-Pro1.
The lens has noticeable CA, but that's correctable in LR. It's bulky, not not so heavy as it looks. But wait, it also has heavy corner darkening/vignetting, usually correctable in LR.
Despite these obvious flaws, why did I buy it again and use it every work day since? Because of its class-leading resistance to distortion. I photograph real estate interiors, and I won't deliver work with barrel distortion. Especially, I hate trying to correct complex/moustache-style distortion such as the S 8-16 produces, with verticals rendered differently depending on their position in the frame. No global adjustments can fix that. The Sigma 12-24, however, needs only a little LR correction, usually less than -5%. Sometimes even a little pincushion distortion appears, which suggests how closely the design aims for the perfect level. When I face dozens of images to process at the end of a long day, this lens saves me many minutes per day.
It's certainly a pity that the new Sigma Art 12-24 isn't meant for us, but I wouldn't pay four figures for it anyway.
| | | | | New Member Registered: March, 2012 Posts: 20 | | Review Date: April 7, 2013 | Recommended | Price: $600.00
| Rating: 9 |
| Pros: | No vignetting, negligible distortion/aberration | | Cons: | Front element, inability to take filters | |
This was one of the first lenses that I bought when I got into Pentax, blame it not on "lens lust" but the ever elusive "Pentax FF" lust. I figured this would be one hell of a lens on a Pentax FF. Unfortunately I am still left figuring :-P
I own the non-HSM version. As with all Sigma EX lenses, the overall build quality is excellent. The rings are well damped and have smooth rotation. Where this lens really shines is the lack of aberrations and vignetting. Sharpness is great, though not outstanding. On my K-5, resolution of 'detail' is better than the most consumer grade/third party lenses.
With an aperture range of 4.5-5.6, the lens is far from being 'fast' (a major gripe) but the need for a fast lens is less in landscape photography, and since most of my shooting is done stopped down, it doesnt appear to be a significant flaw. Also the SR in Pentax gives you at least 1.5 stops of advantage so its effectively like using a f/2.8 lens on Nikon/Canon cameras. Further I notice that the f/4.5 aperture is available right up to the focal length of 17mm. Since I use the lens primarily in this range, it effectively behaves as a 12-17mm f/4.5 lens for me.
The biggest 'con' and perhaps the only one would therefore be the protruding front element and the resultant susceptibility to flare. I notice that even when there a light source placed on the sides, "purple streaks" start to appear on photos. This necessitates the use of filters but the lens wont take any. Filters can only be mounted using clamps or a bit of engineering but it makes the setup really conspicous. Probably the best workaround is to mount a filter on the ring used to stick the front lens cap and use the lens between 14mm onwards since this ruse leads to vignetting between 12-14mm.
Overall I'd say this is a fantastic lens. Highly recommended.
| | | | | Inactive Account Registered: April, 2011 Location: near Berlin Posts: 9
1 user found this helpful
| | Review Date: January 24, 2012 | Recommended | Price: $350.00
| Rating: 9 |
| Pros: | sharp, nearly no CAs, very low vignetting, fast AF, build as solid as a rock | | Cons: | a bit heavy, no filters usable, slow aperture | |
This lens is maybe not as wide as most 10-20 or the 8-16 but it's very well. I love the fact that this lens shows nearly no vignetting and is sharp from wide open. Although it is not as fast (aperture) as some other lenses, but what do you need that for when taking photos with such a lens. So, also Bokeh is not that important. What I love most is the handling. It fits perfectly to my K-5 and to my hands. The fast AF is also nice to have. I don't miss any HSM  The only thing I don't like is the front element. It's impossible to use filters.
Compared to lenses I formerly used (Sigma 10-20/4-5.6, Pentax 15/4) this is my favourite!
| | | | | Junior Member Registered: May, 2009 Location: Charlotte, North Carolina Posts: 27
2 users found this helpful
| | Review Date: February 12, 2011 | Recommended | Price: $485.00
| Rating: 9 |
| Pros: | Sharp, Fast-focusing, Good build quality | | Cons: | Heavy, Huge front element that precludes filters | |
The picture listed is actually the older, non-HSM version, which is also the version I have. The barrel is marked 12-24mm 1:4.5-5.6 DG with EX lower on the barrel.
This is a chunky, well-built lens. It is fairly large and has a permanently attached hood that prevents the use of filters. There is a cludgy way to take the cap apart and use it to mount filters, but the vignettes heavily so this really isn't an option for me.
This lens is crazy sharp at all apertures and focal lengths. There is little or no distortion, which is very nice in a lens with this focal length, especially for a zoom.
This is a full frame lens and mounts nicely to older Pentax film bodies, where it is CRAZY wide.
Look out for flare and contrast problems when stray light hits the front element. With these focal lengths it can be tricky to keep bright light sources out of the frame. In fact, at 12mm, it can be tricky to keep your shoes out of the frame...
Very nice lens, and if it were a tad lighter I would take it everywhere. 24mm on the long end (36mm equivalent on APS-C) makes it useful reasonable to keep on the body at all times, since you can still take 'normal' pictures.
| | | | | Veteran Member Registered: February, 2009 Location: egypt Posts: 435 | | Review Date: March 13, 2009 | Recommended | Price: None indicated
| Rating: 9 |
| Pros: | well built,sharp | | Cons: | heavy | |
ITS MY BEST LENS UNTILL NOW,SHARPEN,FANTASTIC COLORS.
| | | | | Senior Member Registered: February, 2008 Location: Paris Posts: 222
1 user found this helpful
| | Review Date: August 28, 2008 | Recommended | Price: $450.00
| Rating: 8 |
| Pros: | Built, very low barel distortion considering the focal lengt, the widest FF lens you can find | | Cons: | Impossible to use filters, slow. | |
I was looking for something very wide for my GX-10 but I wanted to have something that could be used on a film body (which I still don't own) so my choice went to this lens.
I already had another Sigma EX so i felt pretty confident. I am not disappointed.
Some may consider it slow, but for the use I have of it, it is not a problem. The built in very good. The front element sticks out so you can't use filters.
The pictures are reasonably sharp wide open, and good stopped down. There no vigneting at any focal length and any aperture.
To me the best surprise was the barrel distortion. It is VERY well controled at all focal lengths.
Here is a sample at 14mm f9:
And this is at 19mm f9:
If i gave this lens an 8 only it is because of the front element which flares quite a bit and prevents you from using filters, and because I am used to lenses that have slightly better contrast and colors. But overall, I am very happy with my investment.
| | | | | New Member Registered: July, 2008 Location: london, UK Posts: 17
1 user found this helpful
| | Review Date: July 9, 2008 | Recommended | Price: None indicated
| Rating: 8 |
| Pros: | wide and full frame capable | | Cons: | using filters | |
You have two choices with Sigma, the 10-20 digital only or the 12-24 full frame. The latter is a big bugeye lump of glass but i'm very happy with it. The only downside is you cant use filters at the wide end. I have used it as true 12mm on a film body and the results seem fine to my non expert eye and very interesting photographically.
| | | | | Pentaxian
Moderator Emeritus Registered: May, 2007 Location: Edmonton Alberta, Canada Posts: 10,643 | | Review Date: March 15, 2008 | Recommended | Price: $600.00
| Rating: 9 |
| Pros: | Sharp Well built great IQ | | Cons: | Some barrel distortion odd hood | |
This is a great overall lens. It's full frame which I felt was an advantage on the Pentax version. There's no vignetting with this lens because of that. Also has the aperture ring as well. Slight barrel distortions which are easily corrected in PP. Normal and to be expected in an ultra wide lens. A little slow but all these lenses in this range are. Super solid build and a bit heavy and large.
Only complaint is the hood idea. Similar to the Pentax 31mm. Hood is fixed and filters can be used with a collar that is provided but only at about 16mm to 24mm. Wider than that there is some corner vignetting. Should have had a way to remove the hood and add a filter collar that would cover the entire FOV. The design is partly due to the front element that curves outward.
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