| Author: | | New Member Registered: June, 2018 Location: Houghton, Michigan Posts: 1
7 users found this helpful
| | Review Date: October 3, 2018 | Recommended | Price: $375.00
| Rating: 10 |
| Pros: | wonderful IQ, aperture, focal range, 82mm filter thread | | Cons: | AF issues on K-1, some CA's | | Sharpness: 10
Aberrations: 6
Bokeh: 8
Handling: 8
Value: 10
Camera Used: K-1
Autofocus: 8
New Or Used: Used
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I've spent quite a while searching for the best wide angle landscape lens for the FF K-1. My short list:
Pentax FA 15-30mm f/2.8 ED SDM WR
SMC Pentax-FA 20-35mm F4 AL
Sigma 20-40mm F2.8 EX DG
Tokina AT-X 20-35mm Pro F2.8
This lens' IQ is at least on par with the rest, is ~$500 cheaper than the 15-30mm, ~$300 cheaper and has a full stop on the Pentax 20-35mm, and is much easier to find than the Tokina 20-35mm. Not to mention it has a filter ring - more than the 15-30mm can say! I've concluded this lens is quite possibly the single greatest landscape, nature, and architecture lens available for the FF K-1. There is little reason to wish for primes with such an incredible (but rare!) piece of engineering.
The focal length covers nearly any situation you might need when covering landscape work - apart from the few times when you might miss a FL in the 14-19mm range. Note at 20mm the use of panorama merging and Composition Adjustment on the K-1 can increase the FOV to ~17mm without vignetting with zero parallax errors, making this a 17-40mm if needed  . This lens does suffer from somewhat nasty CAs at extreme edges and corners on FF, but any photographer worth their salt can easily eliminate any CA's and distortion from this lens in a few clicks. Sharpness is very usable at f/2.8, and by f/4 and f/5.6 is incredible, except for extreme corners. I find f/11 and f/16 for landscape shots will give you incredible IQ corner to corner, edge to edge. Those of you shaking your heads thinking "diffraction" - you may lose an eensy weensy bit of sharpness at the center, but f/16 can improve the extreme corners to near perfection in a pinch.
The bokeh on this lens rarely shows itself with my use case (small apertures). When you do find it, especially towards the long end, it's somewhat boring.... not unpleasant, but lacks character.
There is one major caveat with this lens - the AF firmware on many copies (including mine) seems to be faulty on digital bodies, including the K-1. The issue is most pronounced at wider FL's and is not front/back focusing - focusing adjustments in-body do not remedy the problem. Simply put, the lens is unable to ever provide uniformly accurate AF across the different focal lengths and apertures, especially wide-open. I feel this is something that may be present on many folk's copies, yet they simply don't notice as it's "close enough" at smaller apertures (at which these wider FL's are commonly shot). I've heard of countless copies of this lens with the same issue with no solution from Sigma.
As a result, I use this lens exclusively in MF, where it performs admirably. the focusing ring is nicely dampened and provides a reasonable range for a lens of this FL range. Perfectly usable wide open with LV zoom focusing, and stopped down you can simply use hyperfocal distance to get a perfectly sharp image.
Although I've seen countless complaints about the 82mm filter thread, this is one of the biggest reasons I purchased this lens! Screw-in filter threads of any size are somewhat rare for lenses of this FL and aperture. As a college student with limited space, often traveling long distances to get a shot - a filter kit isn't always feasible. The ICE 82mm 10-stop ND is available for around $35 and provides no noticeable degradation of IQ at an extremely affordable price.
Overall, this lens is easily a professional quality landscape lens with second-to-none IQ. If you're on the hunt for a FF landscape lens to match with the K-1, look no further - as long as you know how to MF! My only issue with this lens is it's availability - good luck finding one. I don't think you'll see mine for sale any time soon.
| | | | | | | New Member Registered: December, 2017 Posts: 2
1 user found this helpful
| | Review Date: December 1, 2017 | Recommended | Price: $650.00
| Rating: 10 |
| Pros: | Sharp wide open, constant 2.8, excellent focal range | | Cons: | CA | | Sharpness: 10
Aberrations: 6
Bokeh: 8
Handling: 10
Value: 10
Camera Used: K-1
Autofocus: 8
New Or Used: Used
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Amazing lens. This is the workhorse in my bag for reportage work, product photography and landscapes. I rarely miss my primes when this is on the camera.
The 20-40mm range (plus a pair of feet) pretty effortlessly covers most situations for me. Constant fast aperture is fantastic for shooting crowds and events in difficult lighting, especially given that the lens is very sharp wide open. Stopped down this takes stunning landscape shots with surprisingly good colour for a Sigma IMO- looks more like Pentax colours. Focuses very close for a super-wide, and this has been very useful for dramatic environmental portraits.
Manual focus is comfortable, and AF is decent- not too loud as there isn't heaps of travel. I did have to set the focus adjust on my camera body to -7 to get reliable focusing though.
Some say there's barrel distortion @ 20mm, but to me it looks negligible- i've never needed to correct it in post, but I'm also not shooting brick walls for a living. I'm not a bokeh elitist but the out of focus areas are okay to my eye and the f2.8 makes subject isolation reasonably easy to achieve at 40mm. There is significant purple and green fringing, but this can be corrected.
This is an anomaly of a Sigma lens, and i'm baffled at why it is so uncommon. Overall I love this lens, largely because i'm able to use it on all my film bodies too  | | | | | New Member Registered: October, 2017 Posts: 1
1 user found this helpful
| | Review Date: November 24, 2017 | Recommended | Price: $420.00
| Rating: 10 |
| Pros: | sharp, colors rending, AF | | Cons: | none | | Sharpness: 10
Aberrations: 10
Bokeh: 9
Handling: 10
Value: 10
Camera Used: K3
Autofocus: 10
New Or Used: 10
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My prefered lens.
I also have the famous Pentax FA 20-35mm but the Sigma's range is very good.
It's heavier but it's not a problem.
Sigma's Sharpness and colors rending are better.
With my Pentax DA 14mm and my 70mm Limited it's just a complete equipment... | | | | | New Member Registered: June, 2016 Posts: 11
2 users found this helpful
| | Review Date: October 29, 2016 | Recommended | Price: $700.00
| Rating: 10 |
| Pros: | Everything | | Cons: | moderate CA | | Sharpness: 10
Aberrations: 7
Bokeh: 8
Handling: 10
Value: 10
Camera Used: K-1, LX, KR5 sII
Autofocus: 9
New Or Used: Used
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Perfect in just about every way, particularly:
- flare resistance is excellent, especially at the wide end
- very sharp
- Excellent colour rendition
- The manual focus is really useable, very nicely dampened, and the throw is just long enough for a wide zoom. This is usually a major gripe for me with AF lenses, such as the Sigma 24-70mm.
- has an aperture ring, so compatible with k mount film bodies
Subjectively the rendering is fine for me, though it doesn't have the 'pop' or creamy out of focus areas of high end primes that others may crave
The only real negative (on my copy perhaps?) is pretty nasty CA. Thankfully it's consistent and easily removed with software. Still rate this lens a solid 10 overall
I have quite a few lenses, but this has quickly become my 'normal' lens. Most of the time i'm perfectly happy with it at 40mm, where I would usually reach for a 50mm prime. Absolutely kills the Sigma 24-70 and 24-60, I sold them both immediately.
EDIT: One year later, this is still the only lens I take with me 90% of the time- both on the K-1 and film. I'm completely in love with the focal length, and i don't see there beinga direct competitor anytime soon. Never selling.
| | | | | | | Senior Member Registered: June, 2016 Location: Paris Posts: 124
1 user found this helpful
| | Review Date: June 23, 2016 | Recommended | Price: $700.00
| Rating: 10 |
| Pros: | built, optics, bright | | Cons: | none | | Sharpness: 10
Aberrations: 10
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K-1
Autofocus: 10
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This lens is one of the best surprises from sigma for a digital FF pentaxian.
A pity it was discontinued.
I can't think of a negative aspect for this lens.
Of course , filter size is 82. it may seem big, but i see no complaint on 24-70mm that are the same.
The perpective at 20mm is great.
When compared head to head for wide angle portraits with the P FA 20mm 2.8 , this lens has something more, as i can decide to zoom in a bit or not in different circumstances.
In terms of sharpness it surpasses the FA 20mm at 2.8, especially in corners.
The only downside might be bokeh at 40mm. It's not the Pentax 40mm 2.8. But if background well choosen, it can be great.
Flare is very well controlled for a big front element, and this lens has no HSM, which may be a good point for a photographer's piece of mind, in time.
AF is amazingly fast and accurate on K-1.
If you can find one and can test it, go for it.
| | | | | Veteran Member Registered: September, 2012 Location: Gloucester Posts: 1,199
1 user found this helpful
| | Review Date: October 24, 2013 | Recommended | Price: None indicated
| Rating: 9 |
| Pros: | Sharp and bright; robust | | Cons: | 82mm filter thread; large and quite heavy | | Sharpness: 9
Aberrations: 9
Bokeh: 8
Handling: 8
Value: 10
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I rediscovered this lens in a drawer a few months ago. I bought it way back in my film days, and can't remember how much I paid for it. I hardly used it then and have not used it anger since I went digital. However, encouraged by the good reports here, I decided to put it through its paces with some spectacularly unscientific tests in the garden, and at an improvised test target. I was rather surprised at how sharp the lens is even wide open throughout its zoom range. Focus is reasonably quick and positive. For fun, I set it at 31mm wide open and compared it with my 31mm Limited lens. Unsurprisingly, the Limited blew it away at f2.8, but the Sigma was by no means disgraced. At f1.8, the 31 was still better than the Sigma at f2.8, but they were in the same ball park. I shall certainly be using this lens more, but it will really come into its own when Pentax bring out that full-frame unicorn everyone talks about.
From my brief tests, the lens appears to have aberrations pretty much under control, and seems to have less PF than the 31 Limited. I can't really comment on the bokeh as yet, but this is not a primary concern of mine in a wide-angle lens. Because of that, I gave it an 8 in line with previous reviews.
| | | | | Veteran Member Registered: September, 2008 Location: Phoenix, AZ Posts: 1,448 | | Review Date: August 19, 2013 | Recommended | Price: $290.00
| Rating: 10 |
| Pros: | IQ, F2.8 | | Cons: | Contrast, 82mm Filter Size | | Sharpness: 10
Aberrations: 9
Bokeh: 8
Handling: 9
Value: 10
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I also own the Pentax FA20-35, and while in Yellowstone/Grand Teton, my girlfriend remarked, "Gee, it'd be nice to have a lens like that", meaning color, IQ and all the stuff that make you go Hmmmmm.
See my review of the FA20-35 for how much I like THAT lens for perspective.
So.... I decided this Sigma lens got enough good reviews that for it's price, it would make my GF happy with it's IQ and give her a landscape lens similar to mine.
Well, SHE now has the 20-35! After a series of test shots of some quite boring palm tree trunks and garden rock, I decided this lens was actually sharper. Granted I had to zoom to about 150% to notice a difference, but hey, I was doing an in depth comparison right?
The FA has a little more saturation and contrast, almost a false red? For example, the brown tree trunks seemed a little darker brown, but their texture lost a bit of detail. Thus I'm concluding more saturation and contrast, though I could be wrong. And for me, what the Sigma gives up in saturation and contrast is easily fixed in PS.
As far as IQ, I generally could care less about f2.8 or f4, since I want depth of field. So all of my test shots were at f8 and smaller. What pleased me most, unlike a couple other Sigma EX (24-70) lenses I've had, is that at f22 the image wasn't mangled (chunky/blotchy whatever you want to call it). This was something I really loved about the FA, it was a diffraction be damned lens on my K5iis, and the Sigma is it's equal. I even compared it to my DA40 and was satisfied I wasn't losing anything at 40mm, either.
One final note, although the FA20-35 is a great lens, it is plastic and I've actually caused the zoom to contract while shooting with a graduated ND filter handheld over the barrel. That was another "little" aggravation, that the Sigma doesn't have, because It's built like a tank. That's another reason I kept the lens, it will add weight to your bag, and the gf prefers a little lighter kit. But I once lugged around the Bigma on hikes, so this lens won't kill me. I actually like the balance and heft a little better for handheld shots, too.
Overall, I'd say the Sigma 20-40 is at least the equal of the FA 20-35, which has been graded as a pro quality lens by those who know a lot more about photography than me. Therefore, I'll call this another FF pro quality lens option, IF you can find it.
Just don't expect to see mine for sale any time soon.
| | | | | Veteran Member Registered: June, 2011 Location: Near Sydney, NSW Posts: 331
1 user found this helpful
| | Review Date: April 8, 2013 | Recommended | Price: $410.00
| Rating: 10 |
| Pros: | Very little distortion for its W/A, great colours, contrast and sharness - f2.8 when you need it | | Cons: | No FF body to put it on | | Sharpness: 10
Aberrations: 9
Bokeh: 10
Handling: 10
Value: 10
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People who are saying this is big and heavy - really? I use it on a tiny film body and still don't find it too bad - on my K-5 it's not an issue at all, so if there is ever a FF body (which will of course be bigger than the K-5) then this will be one of those beautiful balanced landscape lenses on it!
I bought this so as to improve my landscapes, specifically to work with film so as to make sure I tried to make every shot count - and it has worked, but it's also shown itself to be a fantastic lens.
40mm f2.8 looks stunning on film, still wide but with great shallow D.O.F.
FF UWA lenses are lacking in Pentax mount, so if we do get a FF body, I'm hoping for more support from Sigma (maybe something like the 17-40 that Canon has) - but if not, this is till great.
| | | | | Veteran Member Registered: April, 2011 Location: Canberra, Australia Posts: 582
1 user found this helpful
| | Review Date: December 29, 2012 | Recommended | Price: $290.00
| Rating: 10 |
| Pros: | Crispy clean images. Perfect focal lengths for all kinds of photography | | Cons: | Should come with an OH&S heavy lifting sticker. | | Sharpness: 10
Aberrations: 8
Bokeh: 9
Handling: 3
Value: 10
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This is a spectacular lens for its price range. Shame it's so epically big and heavy.
But considering what you pay; the weight drawbacks are worth it.
| | | | | New Member Registered: August, 2011 Location: Boston Posts: 1 | | Review Date: November 18, 2012 | Recommended | Price: $560.00
| Rating: 10 |
| Pros: | Everything - sharpness wide open, sharpness stopped down, no vignetting at 20mm (barely any on 35mm film), fairly light but solid | | Cons: | Maybe could have a TOUCH more zoom, like 20-50mm (would be nice on APS-C) | | Sharpness: 10
Aberrations: 10
Bokeh: 10
Handling: 10
Value: 10
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Like I said in the pros and cons, really the only thing I can fault with this lens is the limited 2x zoom range.
When they made this lens, the very best constant f2.8 zooms were not much more than 2x zoom - and even these days, I suppose you'd put this up against something like the Canon 16-35mm f2.8 - and guess what, this is a 3rd of the price (when you find one), and I regard the quality as the same (I have borrowed a friend's 5D-ii and 16-35mm f2.8 lens).
But two more things I want to say on that issue: To keep the sharpness at an outstanding level, they've made it 2x zoom rather than giving it an extra few mms at either end. I'd prefer that.
The other thing is - remember this is a full frame ultrawide angle. Us Pentaxians have gotten used to APS-C - which this lens is still gorgeous on by the way (30-36mm, f2.8 -  aw yeah) - but on full frame it's what we APS-Cers would call a 13.5mm - 27mm - so very wide - but these smokes anything you'll get on APS-C for resolution etc. I have blown up film shots of this, up to 16" x 24" prints, and they look stunning. I haven't done that much on my APS-C (with the 10-20mm f3.5) but I have done 12" x 18" and they're not as high quality, so I dunno how you'd go with another 50%!
You get what I mean... anyway, I hope Pentax release something like this, (maybe even better?!) if that full frame camera ever does come - but I'll be hanging on to my copy of this for film anyway, and if a FF digital comes, I'll be whacking it straight on (and never taking it off)!
| | | | | Veteran Member Registered: February, 2009 Location: egypt Posts: 435 | | Review Date: May 22, 2012 | Recommended | Price: $320.00
| Rating: 8 |
| Pros: | sharp | | Cons: | big but not heavy | | Sharpness: 9
Aberrations: 8
Bokeh: 8
Handling: 6
Value: 8
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sharp even wide open.
it is big but easy to handle .the construction is well made.
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| | | | | Senior Member Registered: October, 2008 Location: Great Plain, Hungary Posts: 204 | | Review Date: November 3, 2010 | Recommended | Price: $150.00
| Rating: 10 |
| Pros: | Simply great in every aspect | | Cons: | A bit big | | Autofocus: 8
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I had a 20-35mm range zoom but I always felt it is some sort of short at the longer end. Then one of my fellow Pentaxians decided to change system because Pentax does not offer FF digital cameras and let this lens go for nearly nothing... or at least half the price you usually see these lenses go for... if you see one pop up occasionally.
All I can say that this is one of my best investment in a lens. The zoom range is very handy in most normal life situations from indoor shots to near normal perspective 40mm shots. The 2.8 constant aperture is really bright and helps a lot composing your pictures while picture quality is great with nice bokeh at 40mm.
The only drawback might be its big size. Not a discrete lens to say the least and 82mm filters cost at least as much as I paid for the lens itself.
Update 18/12/2016: Looking back the last six years I have had this lens. I think it is still great and do not find its size a burden. I have learnt to live with it. It has given me some cracking photos on film.
Update 23/04/2017: Bought the K-1 and tried it with the Sigma. Unfortunately my copy of the lens suffers from erratic focusing. People around forums (elsewhere as well) say very mixed opinions and the main problem seems to be the lens' firmware. Although it was very good on my MZ-S its AF performance is pretty poor on the K-1. It is not the speed but missing the focus point. Seems to be a general problem with many copies of this lens.
| | | | | Junior Member Registered: February, 2008 Location: UK Posts: 34
1 user found this helpful
| | Review Date: July 6, 2009 | Recommended | Price: $350.00
| Rating: 9 |
| Pros: | Build, IQ | | Cons: | Just not wide enough, Huge, Big. | |
Ok i borrowed this lens from a friend as i needed something wider than i had at the time. its a Very good lens. In the end i was happy with the results and can recomend this lens to anyone, although for the money i would get the Pentax 16-45 f4, which i did a couple of days latter and have never looked back.
| | | | | Forum Member Registered: January, 2009 Location: Sydney Posts: 86
1 user found this helpful
| | Review Date: February 10, 2009 | Recommended | Price: $300.00
| Rating: 9 |
| Pros: | Superior optics, good even for low light | | Cons: | It is quite big physically and doesn't quite balance on camera | |
This is the second lens I got from after my kit lens.
Still remember how impulsive it was to win this lens from an online auction site. I was like "what the hack" after I find out I have to pay only 20% of the RRP for this new copy. With scepticism, I was concern to receive a lemon! But to my surprise, the lens was in perfect condition.
At first I wasn't appreciating its performance, mainly because as a beginner I was eager to explore the variety of other lens avaliable. Now, after I had explore and acquire well over enough lens to judge, I'll say this lens had given me more than impressive images, prehaps the best images I've taken were mostly from it.
This is my main walk around lens and one that is unlikely to be replace!
Sigma 20-40mm f2.8
Sydney Darling Habour k10d 26mm 20sec f22 iso400 (love the stars with countless blades, from good quality lens)
Sydney Habour bridge k10d 40mm 1/350sec f8.0 iso200
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Site Supporter Registered: June, 2008 Location: Florida Hill Country Posts: 17,377 | | Review Date: September 7, 2008 | Recommended | Price: $254.00
| Rating: 9 |
| Pros: | 2.8 max across range; IF; quick focus for non HSM | | Cons: | Big; 82mm filter | |
The 20-40mm f2.8 EX Aspherical DG DF is sharp even wide open. It also does well for action shots and in low light. I have no complaints with the color and contrast. It focuses quickly for a non HSM lens. I got this to replace the DA 18-55mm II that came with my K200D. While I liked the kit lens, it was just too "slow" in the situation that I was using it in. This lens is well made and looks good and balances well on my k200d even though its big (1.3 pounds). However, it is not as heavy as it looks. It is easy to handle for me, but with someone with smaller hands, I don't know. I could see it being front heavy on a light slr/dlsr such as an EOS 10s. I will link to some images later on. I was considering the Tamron 17-35 F/2.8-4 Di LD Aspherical (IF) Macro but it weighs 470 grams and is slower at the longer end. This lens is more common in the Nikon mount but is worth looking for in the Pentax mount if you need a lens in this range. It has a usable dual focus system, but requires switching the body to mf first although it has a position on the focusing collar for MF or AF. It also can accept rear filters which may not be a bad thing since it takes 82mm on the front.
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