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HD Pentax-DA 20-40mm F2.8-4 Limited DC WR

Reviews Views Date of last review
52 210,875 Sat October 10, 2020
Recommended By Average Price Average User Rating
92% of reviewers $731.95 9.17
HD Pentax-DA 20-40mm F2.8-4 Limited DC WR

HD Pentax-DA 20-40mm F2.8-4 Limited DC WR
HD Pentax-DA 20-40mm F2.8-4 Limited DC WR
HD Pentax-DA 20-40mm F2.8-4 Limited DC WR
HD Pentax-DA 20-40mm F2.8-4 Limited DC WR
HD Pentax-DA 20-40mm F2.8-4 Limited DC WR

The HD Pentax-DA 20-40mm F2.8-4 Limited DC WR is the first zoom lens to join the Pentax lineup of ultra-compact "limited" lenses. This lens features a sleek all-metal barrel manufactured to very high standards.

This is also the first Limited series lens to feature silent DC autofocus as well as a weather-sealed design. Like the other HD Limited lenses, this lens features Pentax's latest lens coating promising less ghosting and flare.

As is standard for all premium Pentax lenses, this lens allows for full-time manual focus adjustments (Quick shift) and it is treated with Pentax's Super Protect coating to protect the front element from dust and scratches

The lens covers a wide-angle to normal focal length range, and is compatible with Pentax APS-C DSLRs. It will be available in both black and silver in December, 2013 for $999.

HD Pentax-DA 20-40mm F2.8-4 ED Limited DC WR
©, sharable with attribution
Image Format
Lens Mount
Pentax K
Aperture Ring
Automatic, 9 blades (rounded)
9 elements, 8 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
AF (in-lens motor)
Min. Focus
28 cm
Max. Magnification
Filter Size
55 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 39-70 ° / 33-62 °
MH-RA 55mm
Soft pouch P70-150
Lens Cap
Metal push-on O-LW65A
Weather Sealing
Yes (WR)
Other Features
Diam x Length
71 x 68.5 mm (2.8 x 2.7 in.)
283 g (10 oz.)
Production Years
2013 to present (in production)
$496 USD current price
Engraved Name
HD PENTAX-DA 1:2.8-4 20-40mm ED Limited DC WR
Product Code
23000 (black), 23010 (silver)
User reviews
In-depth review
Unofficial Full-Frame Compatibility Tests by Pentax Forums
★★☆ Full coverage at some F-stop and focal length combinations
Show details
One aspherical element, one ED and one extra-low dispersion element.
No autofocus on older bodies (*istD series, K100D, K110D, and film).

Black and silver

Supersonic AutofocusQuick ShiftWeather SealedAutomatic ApertureAPS-C Digital Only
Purchase: Buy the HD Pentax-DA 20-40mm F2.8-4 Limited DC WR
In-Depth Review: Read our HD Pentax-DA 20-40mm F2.8-4 Limited DC WR in-depth review!
Sample Photos: View Sample Photos

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Senior Member

Registered: October, 2011
Location: Cambridge, Ontario
Posts: 179

6 users found this helpful
Lens Review Date: December 8, 2013 I can recommend this lens: Yes | Price: $999.00 | Rating: 10 

Pros: Beautiful construction, IQ, very light
Cons: Cost, but you get what you pay for. 55 mm filters
Sharpness: 10    Aberrations: 10    Bokeh: 9    Autofocus: 10    Handling: 10    Value: 9    New or Used: New    Camera Used: K3   

In my opinion, the first Limited Zoom is a winner. If you like Limited primes, this is the zoom for you. At under 300 grams it is lighter than an FA 31 and is well balanced on the camera. This lens is a great walkabout lens for a landscape photographer and just right for my general use. It is weather sealed which is a bonus. It complements my fleet of Limited primes very well.

Image quality is stunning and the DC motor is quiet. Autofocus is fast even indoors. The ergonomics are amazing, you can carry this lens all day and the camera is not nose heavy. It is plenty fast for my use, weight is a greater concern to me.

Many people will consider this lens expensive. My Canikon friends disagree, they pay much more for good glass. The new Sigma 18-35 is faster but rivals a telephoto lens in size and weight. There is no way I would carry that all day.

I would highly recommend this lens. If you like Limited lenses before, you will like this one.
New Member

Registered: July, 2012
Location: Ballarat, Victoria
Posts: 24

2 users found this helpful
Lens Review Date: December 12, 2013 I can recommend this lens: Yes | Price: $999.00 | Rating: 9 

Pros: Lightweight, build quality, WR, colour and sharpness
Cons: Would be nice if the lens was a constant f2.8
Sharpness: 9    Aberrations: 9    Bokeh: 9    Autofocus: 9    Handling: 10    Value: 9    New or Used: New    Camera Used: Pentax K-5   

I received my lens yesterday and had the chance to snap off some shots on my trusty K-5 before it had to go under the tree. This lens is a Christmas present from my wife and I was fortunate enough to be home when the lens was delivered. I managed to convince my good lady that I needed to test the lens before wrapping to make sure I had not received a faulty copy. I only had a short time testing the lens but I managed to get off a few shots. My initial impressions are very favourable! The lens appears quite sharp and I particularly like the colour rendering and the bokeh is also very pleasing.

I bought this lens to cover 35mm and 50mm focal lengths (35mm equiv) and I can see it being mounted to my camera full time. It will be the perfect walk around lens. Nice build quality, light, sharp, great colours and weather sealed! Perfect!

I also own the Tamron 17-50mm f2.8 but I can already see that I much prefer the handling and images from the Pentax DA20-40mm lens on my K-5. Feels like I have two primes built into one lens with this unit. The Pentax is smaller and lighter than the Tamron and the autofocus feels snappier. I will probably sell the Tamron now as I can't see it being used again. The images out of the DA20-40mm are much more appealing to me.

I have given a score of around 9 based on my limited time with this lens. Once I have had more time shooting I will update my score. The only wish I have at the moment is that it had a constant aperture of at least f2.8. But then the lens would probably need to be larger and heavier.
Site Supporter

Registered: February, 2012
Location: Adelaide Hills, South Australia
Posts: 9,241

7 users found this helpful
Lens Review Date: December 14, 2013 I can recommend this lens: No | Price: $900.00 | Rating: 7 

Pros: Physical beauty and handling, DC AF and WR
Cons: Weak at the short end, too big for a DA limited
Sharpness: 7    Aberrations: 8    Bokeh: 9    Autofocus: 9    Handling: 10    Value: 6    New or Used: New    Camera Used: K-3   

I had high hopes for this lens. It looks and feels amazing, and it focusses quickly, quietly, and nice and close. Flare resistance is pretty reasonable. It is disappointingly big though.

Between 30mm and 40mm the IQ is excellent, and the bokeh is superb despite only being f/3.5-4.0 in that range.
Unfortunately edge performance is pretty hopeless wide open at the wider end, and only really becomes useable beyond f/5.6, and good beyond f/8.0.

Unacceptable in such an expensive lens.

I will be sticking with my DA*16-50 for weather-proof zooming in that range, and with my limited primes for fun/ultimate IQ.
Site Supporter

Registered: February, 2008
Location: Emeryville, CA
Posts: 1,119

12 users found this helpful
Lens Review Date: December 16, 2013 I can recommend this lens: Yes | Price: $900.00 | Rating: 9 

Pros: Lightweight, WR, Rendering, sharpness,
Cons: Slightly cooler color than other DA ltd. primes
Sharpness: 10    Aberrations: 9    Bokeh: 9    Autofocus: 10    Handling: 10    Value: 10    New or Used: New    Camera Used: K-5   

I had high hopes for this lens. I had been using my 15, 21, 35, 40 and 70 for about 3+ years but I wanted a light WR zoom with those same lovely ltd. qualities. I can say that the 20-40 has met my high hopes and carries all of the qualities I was looking for. The build quality is excellent. The zoom ring is smooth and in my opinion nicer than the DA*. I had the 16-50 and still have the 50-135. Although larger than any of the DA primes it still carries that small and light design forward if you compare it to other zooms in this focal range. On my k-5 you can easily 1 hand this although that is not my typical shooting style. It looks and feels great on the k-5. One big benefit over the DA primes is the quiet focus. The other for me is not having to constantly change lenses or locked into a single focal length. I do a lot of hiking in all types of weather so the short time I've had the lens, I find that I'm really loving the convenience of not being locked into a focal length.

The lens is sharp wide open throughout the zoom range. I did have to fine tune the autofocus to get it operating at its best, but that is not unlike all of my other lenses. I tend to think it is more a function of my K-5 rather than any lens. The sharpness was pretty consistent across the frame as well. I will do some testing against the DA35 ltd to test absolute sharpness. That lens is the sharpest I have in my bag and I am curious mainly because from looking at the images that I took with the DA 20-40 it looked impressively sharp.

The one aspect of the lens that will take some getting used to is the color. The ltds. primes rendered slightly cooler than other lenses i had and the 20-40 is slightly cooler than the primes. Again I'm going to do some side by side testing to make sure it isn't just a figment of imagination. I took some landscape and portraits and I really like how the zoom renders its images. I also like the bokeh. It tends to be more smooth and has a nice transition. The other positive aspects of the lens are how contrasty the images are.

Overall, I think Pentax has produced a really stellar performer and like my DA*50-135, the DA20-40 feels like having a bag of primes packed into a single lens. Yes 900 is a lot of money but considering, I already don't miss the DA21, 40, and may consider selling the 35, I'd say it is worth its cost.

12/20/13 Update. I have taken side by side testing with my DA35 and I can say it produces images of equal quality and sharpness. Which for me still seems hard to believe. So I bumped up the Value to 10. Again many may question the cost but, for me it easily replaces 3 excellent primes.

I'd also like to update that if you are coming from using the DA primes and were used to creating sharp star-like patterns with your night shots shot against a bright light source, the rounded aperture blades do take some of that away. You can still create them they are just not as sharp.

2/23/14 Last Update. After a lot of shooting with this lens, I finally decided to let go of my DA35 Macro. For me that says a lot for the DA20-40. The close focusing of the DA20-40 was good enough to for how I shoot. And I just didn't see enough of a difference in sharpness for me to keep the 35 Ltd. Macro. I will also update that the lens does a very good job of flare control. Not quite to the degree of the DA15 but more than commendable. In very high contrast situations you will get some purple fringing if you shoot wide open. I find it more prevalent in the corners rather than throughout the image. Overall I could be not be happier with this lens. Don't let the reviews scare you away.
Veteran Member

Registered: October, 2007
Location: France
Posts: 804

9 users found this helpful
Lens Review Date: December 16, 2013 I can recommend this lens: Yes | Price: $890.00 | Rating: 9 

Pros: IQ, color rendering, "limited" style
Cons: Slow AF, price
New or Used: New   

For the IQ, this lens outperforms the DA21 by a large margin, and it is a f2.8 lens, not a 3.2. The border are a bit soft at 20 mm f2.8 but at F4 it is already largely homogeneous. Flare resistance is excellent.
At 40 mm it is beyond the FA43 limited on the center resolution, but the FA43 is a high performer here, and he challenges the FA43 for the border resolution.
At 30 mm the FA31 outperforms this lens in terms of sharpness, but it is the FA31. CAare very well controlled, better than on the FA31.
In every aspects this lens is a very good performer. The price is a bit steep, though, but expected to be reduced. And we have to pay for the WR and DC engine.
An ideal lighweight combo could be the DA15, this zoom and the DA70.
Inactive Account

Registered: June, 2011
Location: Gulf Coast
Posts: 45

3 users found this helpful
Lens Review Date: January 2, 2014 I can recommend this lens: Yes | Price: $896.00 | Rating: 9 

Pros: Size, classic 35mm focal lengths
Cons: None.
Sharpness: 10    Aberrations: 10    Bokeh: 10    Autofocus: 6    Handling: 9    Value: 9    New or Used: New    Camera Used: K5 ll   

My FA31mm has not been used since it's arrival ! Using in a disciplined manner, not just zooming, I now have classic focal length reportage lenses on my camera. I have found this to be very sharp (maybe to sharp) in the center at all focal lengths even wide open ( f5.6 at 40mm) which is not really my style anyway, f5.6 f8 is what I use for the most part.

Now I have had this for a while I now can give a more realistic review update. I find the auto focus is not very good at all. When it focuses on a subject, very slow by the way, gets a fix on it and will not focus on a new area just a few feet away. It needs to be encouraged to refocus by manually putting it out of focus first. This procedure makes for a very slow lens handling and therefore consider the auto focus very poor. Hope they can fix this with some sort of update.
Veteran Member

Registered: December, 2009
Location: Georgia, VT
Posts: 1,654

18 users found this helpful
Lens Review Date: January 3, 2014 I can recommend this lens: Yes | Price: $896.95 | Rating: 9 

Pros: Light, Small, Build Quality, Picture Quality
Cons: Small-ish Aperture, Slow Auto Focus
Sharpness: 9    Aberrations: 10    Bokeh: 8    Autofocus: 8    Handling: 9    Value: 8    New or Used: New    Camera Used: K-3, K-5, K-x   

I have every SMC Pentax Limited lens with the exception of the 35mm Macro, and that's pretty much my carry-around kit (in addition to a Sigma EX DG 100-300mm F4 on occasion). Out of those lenses, the DA 21mm, FA 31mm and FA 43mm are my most-used, with the FA 31mm taking up the majority of time on my cameras. So when this 20-40mm Limited was announced, I was pretty excited. A Pentax Limited zoom that covers my most-used range? AND weather resistant? YES PLEASE!

I agonized over this lens vs the Sigma 18-35mm F1.8. I'm a real slave to wide apertures, and that Sigma has some mouth-watering specs at a lower price. It's a hard sacrifice going from F1.8 to a variable F2.8-4. But in the end the 20-40mm won me over with its weather resistance, much lighter weight and reasonable size. Also, it's a Pentax Limited.

Of course, the first thing I did when I received the DA 20-40mm is physically compare it to the FA 31mm since that's the one most often on my camera. Turns out the 2 are pretty close. The 20-40mm with the hood removed is almost exactly the same length as the 31mm. The hood is only 1/4" long and no wider than the lens, so it adds no real bulk. The 20-40mm has a slightly larger diameter than the 31mm, presumably to accommodate the focus motor. And surprisingly, the 20-40mm is 2 ounces lighter than the 31mm (10.5oz vs 12.5oz). As far as fitment on my cameras goes, the 20-40mm makes the setup lighter while keeping the overall size about the same.

Build quality is jaw-droppingly good. The zoom and focus rings are flawlessly damped, and there's no give anywhere. Everything is made of aluminum and finished to perfection. I got a silver one to go with my silver K-3 and K-5, and I'm in awe of how well made this lens is. It even surpasses my other Limited lenses. The zoom ring has a great machined look that's reminiscent of my old Super Takumar 50mm F1.4 (although it was a focus ring on that one).

Auto focus is impressive, though less than I'd hoped. The auto focus accuracy is spot-on with my K-3, even in ridiculously low light. It gets perfect focus without any need for the AF assist light, even when I can't see the object I'm focusing on with my own eyes. I guess that's as much because of the K-3 as anything else, but I expected the smaller aperture to have more negative impact.

But as far as auto focus speed, I expected the built-in motor to perform a little better. It's no faster than most screw-drive auto focus lenses I own, and noticeably slower than many, including the DA 15mm, DA 21mm and FA 31mm. Sure, it's silent, but I've never been bothered by the sound of screw-driven auto focus. I would've preferred a screw-drive mechanism in this case if it meant faster performance.

The aperture is something everyone's been talking about ever since this lens was announced. While no DA Limited has ever had a large aperture, for some reason many Pentaxians were surprised when this one followed the exact same trend. There's nothing terribly surprising about a small-ish aperture on a DA Limited lens. I *was* a bit surprised by the variable aperture, but then this is the first Limited zoom ever, so it's not like there was any precedent to make me think it should be otherwise. At first I wasn't sure if this aperture range would suit my needs. Lately most of what I shoot is my baby daughter indoors, for which the FA 31mm was perfect. I was spoiled by being able to shoot at F2.2 and low ISO and having perfect results every time. So the small aperture of the 20-40mm threw me for a loop, and initially I really didn't like it. It was annoying enough that I contemplated sending the lens back and waiting for the Sigma 18-35mm F1.8 after all.

But then I did something weird... I cranked up the ISO. All the way up to 3200! (I almost never went beyond 800 before). Lo and behold, the pictures turned out beautiful! Sure, there was grain, but there was also tons of fine detail. A quick trip through denoising software and a little sharpening made those pictures come out as clean as anything shot at ISO 800. It was a revelation. I'm sure the camera's denoising engine would do an admirable job as well, but I've been a RAW shooter for years and that won't be changing anytime soon. The point is, the small-ish aperture of this lens doesn't have to be a limitation as far as low-light shooting goes.

As for bokeh, the 9 rounded blades do an absolutely stunning job here. Sure, there's less out-of-focus area in the scene due to the smaller aperture, but even F4 gives some very nice bokeh at 40mm when the subject is close enough. It's creamy smooth in front and behind the plane of focus, and it transitions beautifully. On the downside, starbursts from points of light are somewhat disappointing. I needed at least F22 to get any respectable star shape, and having 18 points makes it look a bit odd.

If you read this whole review, I kept the best for last: picture quality! This is what ultimately convinced me that I made the right choice with this lens, despite the smaller aperture. The old cliché "like a prime lens at every focal length" might just apply here. The only softness happens wide open at 20mm, and then only away from the center. Anything else is amazingly sharp, especially on a K-3 with the AA filter disabled. I can't believe the amount of detail and micro-contrast this lens delivers, it's like magic. As far as zooms go, it's quite possibly the best I've ever seen.

edit: to clarify, the edges and corners ARE soft wide open at 20mm, but the center remains very sharp. This is the only range I came across where sharpness takes a noticeable dip. By F4, the sharpness has caught up to the rest of frame again. And I personally don't find the softness objectionable, it's what I'd expect from the wide end of a lens in this focal length range.

Flare? Glare? Nope, not with this lens. I shot right into the sun on a bright Winter morning and only got the faintest amount of glare in the frame, barely discernible at all. I got no flare whatsoever, though. Shot wide open, I can make out the merest hint of purple fringing in the far corners of the frame, but that's it. And that's pixel-peeping at 2x magnification. This is unbelievable, and puts the CA-monster FA 77mm Limited to shame.

I read some comments from other people who ended up with decentered samples of this lens. I know that feeling too well, I experienced the same thing with my DA 15mm Limited. But with this 20-40mm, I struck gold; no quality control issues that I can see whatsoever. Call me lucky... this time.

I've found my new favourite lens, and it is the 20-40mm Limited. I'll be sure and try the Sigma 18-35mm F1.8 as soon as I have a chance, but it would have to be absolutely perfect to get me to change my mind. For now, the 20-40mm is taking the honored place of the FA 31mm as the featured lens on my camera.

UPDATE - January 6th, 2014
I just read the "In-Depth Review" for this lens, and I find it interesting that their findings on image sharpness are completely reversed from my own. They found this lens softer wide open at 40mm, but sharper wide open at 20mm. I guess it's either due to sample variation or different testing methods.

In any case, to give an idea of how sharp this lens is, here's a photo I took at 40mm, F8 and ISO 3200 using a K-3:

You can click on the image to see a full size version. Pay close attention to the eye closest to the camera at 1:1 magnification. That's where the camera was focused.

Second example (sorry, all I have are baby photos recently). This one was taken at 40mm, F4 (wide open), ISO 3200 using a K-3:

Again, on the full size version, pay attention to the eye closest to the camera. The eyelashes are about as sharp as can be. Also, if you look at the right edge of the picture, you can clearly see some in-focus texture in the cushion fabric. Same on the left edge with the blanket, the fabric texture can clearly be made out. Again, this is wide open.

UPDATE - February 1st, 2014

I continue to love using this lens daily for all kinds of different subjects. As far as I'm concerned, this is a constant aperture F4 lens, with F2.8 available to me as a bonus when I really need it. Some of the best zoom lenses ever made have an F4 constant aperture (Sigma 100-300mm F4, Pentax 60-250mm F4, 20-35mm F4, 24-50mm F4, 12-24mm F4, Nikon 16-35mm F4, etc, etc) so when I look at it that way, this lens becomes even more awesome.

UPDATE - July 13th, 2014

I'm starting to think there are some serious issues with quality control regarding this lens' manufacturing. Apparently I got a perfect copy, unfortunately other pentaxians haven't been so lucky. It's impossible to dismiss the complaints from people who have received a decentered copy, or are getting poor results. My copy of this lens continues to excel in every way, not least of which is autofocus accuracy. The focus for ALL my shots taken with this lens is always spot on, it's almost magical. I've needed no focus adjustment on either my K-5 or K-3 with this lens, even at F2.8. Based on this, I've had to increase my autofocus rating from 5 to 8, despite the occasional slowness of the focus motor.

Today I had a chance to try the other lens I was considering before deciding on this 20-40mm: The Sigma 18-35mm F1.8. Sure enough, the image quality with that lens was amazingly good, just as good as the 20-40mm in most cases and somewhat better in extreme cases (like at full zoom). However about 1/3 of my shots with the 18-35mm ended up being misfocused, usually not enough to be obvious on the camera's LCD at a glance, but enough to make some pictures disappointing. It's like the 18-35mm induces a bit of front or back focus, but only randomly, so it can't really be corrected for in the camera. Very frustrating. It even happened on 2 nearly identical shots, back-to-back. One shot was in perfect focus, the other was slightly back focused. This is never an issue with the 20-40mm.

Also, the 18-35mm is HUGE and HEAVY for the type of shooting I've been doing lately. All in all, I'm glad I decided on the 20-40mm rather than wait for the 18-35mm. It turned out to be the perfect choice for my needs. But then I'm lucky I got a good copy... apparently not everyone is so lucky
Senior Member

Registered: July, 2008
Location: montreal
Posts: 136

1 user found this helpful
Lens Review Date: January 16, 2014 I can recommend this lens: Yes | Price: $1,000.00 | Rating: 10 

Pros: small, WR, build quality, IQ
Cons: Some vignetting at 40mm but easily corrected.
Sharpness: 9    Aberrations: 10    Bokeh: 10    Autofocus: 9    Handling: 10    Value: 9    New or Used: New    Camera Used: K-01 and K20D   

I rated it a 10 for me because it does exactely what i wanted from it, that's why i bought it. Sharpness is very good at any focal length and apertures, except at 20mm at f/2.8 in the corners but i don't care. At 40mm there is still some vignetting even at f/13 but it's easily corrected in LR.
I really like it's small size, Limited build quality but with the addition of WR, just perfect !
New Member

Registered: December, 2013
Posts: 2

1 user found this helpful
Lens Review Date: February 7, 2014 I can recommend this lens: Yes | Price: $996.00 | Rating: 9 

Pros: Sharp,great built, compact, good contrast
Cons: Poor quality control - first sample required RMA exchange, marginally useful lens hood
Sharpness: 9    Aberrations: 9    Bokeh: 10    Autofocus: 8    Handling: 10    Value: 7    New or Used: Used    Camera Used: K-3   

My first copy was badly decentered, with the left side very soft and a weird lack of sharpness at 30mm, f/5.6. BH Photo was very good about making a prompt and hassle-free RMA exchange.

The second copy was noticeably better, with excellent sharpness across entire field at all focal lengths when used between f/5.6 and f/7.1 except for lower right corner at 20mm. Closed down, this lens is very good, but it's not really suitable for dim indoor light due to the need to stop down for best results. A bit of localized sharpening and increased clarity in Lightroom generally solved this problem.

Excellent build, weather-sealing, and compact size/light weight were the deciding factors when compared with the much larger and heavier Sigma 18-35mm, which I might have bought otherwise. It is somewhat sharper than my non-VC Tamron 17-50mm toward the edges, but not by a great margin.

It took some time to determine the best way to use this lens for maximum image quality, but I now find it very suitable for general use. Overall, it's sharper than I expected from the Pentax Forum and DXO reviews.
Senior Member

Registered: November, 2009
Location: San Jose, CA
Posts: 103

7 users found this helpful
Lens Review Date: February 24, 2014 I can recommend this lens: Yes | Price: $996.00 | Rating: 10 

Pros: light, sharp, great build, WR, zoom range
Cons: lens hood, price
New or Used: New   

For me, this is a great lens. And I may be the only one who actually likes the strange zoom range, but I do. First a little background. I have all the DA limiteds and use them whenever I have the time to play around with composition and enjoy shooting - which mostly means whenever I am by myself. When I go out with group of non-photography friends though, or whenever the weather isn't exactly right, I would end up going out with my 18-135. Which is WR and very small for the zoom range, but slow, not very great optically and no fun to use. It's much more fun to use limited primes (limited in more then one sense), because creativity often comes from that limitation. With 18-135, I just get complacent, zoom from where I stand and shoot.

But 20-40 changes all of that. It's a zoom, but still very limited. It gives me that possibility to go from 20-40 without changing the lens, and it gives me beautiful photos, very much comparable to limited primes.

It also creates beautiful travel kit with other DAs. My goto ultra light travel kit could easily be 15 for wide angle, 20-40 as basic walkaround and WR lens if it starts raining, 70 for short small telephoto. Replace 70 with macro for little extra reach and macro at the price of added weight. Or with 55-300 for real telephoto. Can't ask for much more. See I do like to travel light.

Scared by reviews here, I did some of my testing when I got the lens. It's sharp as sword in the center! And, I do not think there's a significant issue with corner sharpness, at least on my copy. The lens does have, though, a significant field curvature. If you focus the center at the open aperture, corners, especially at the close focus will be very much out of focus. You can focus the corners - then of course center will be out of focus. I believe for this type of lens it's normal behavior and refuse to be bothered by that. It pretty much disappears once you close the aperture enough, it gets much better at distance. Would I take this lens to take pictures of the artwork in the dimly lit gallery? Hell no, but that's not its purpose either. That's what macro lenses are for. Other then that, the lens is perfectly sharp on my K-3.

Some comparisons.

Compared to DA 21
21 pros:
  • tiny (this may actually play big role sometimes)
20-40 pros:
  • better sharpness over the field
  • WR
  • zoom

Compared to DA 40
40 pros:
  • tiny
  • fast @2.8
20-40 pros:
  • WR
  • closer focus
  • zoom

Compared to DA 35 Macro
35 pros:
  • macro
  • uniform sharpness across the field
  • I believe picture quality is a tiny bit better overall
20-40 pros:
  • WR
  • faster focus, especially when macro start hunting

Compared to 18-135
18-135 pros:
  • zoom range
  • price
  • internal focus
20-40 pros:
  • much better optically (it better be for twice the price though)
  • faster
  • lighter
  • parfocal! - this lens is completely parfocal, which allows you to do nice things, like focus on the (40mm) end, then zoom out and the focus stays the same.

Junior Member

Registered: January, 2013
Location: Texas
Posts: 32
Lens Review Date: March 10, 2014 I can recommend this lens: Yes | Price: $950.00 | Rating: 9 

Pros: Build Quality, Light Weight, Image Quality
Cons: Price, limited range
Sharpness: 9    Aberrations: 9    Bokeh: 9    Autofocus: 9    Handling: 10    Value: 8    New or Used: New    Camera Used: Pentax K30   

Except for the limited zoom range, this lens is very practical: small, light, all-metal, low minimum focusing distance, 49mm filters, very good autofocus and manual focus.

I took only 5 'test' photos with it, the brick house of my neighbor. The results are really excellent, and I don't understand some other reviews:
- I cannot see vignetting!
- Sharpness:
- at 20mm / 2.8: Center 90, Edges 80
- at 20mm / 4.0: Center 100,Edges 90
- at 20mm,5.6: Center 100,Edges 90
- at 40mm/4.0: Center 90,Edges 80
- at 40mm/5.6: Center 100,Edges 90

'100' being near-perfect.

I love it!
New Member

Registered: May, 2012
Posts: 3

3 users found this helpful
Lens Review Date: March 31, 2014 I can recommend this lens: Yes | Price: $1,000.00 | Rating: 10 

Pros: sharp, build quality, silent
Cons: size, hood
Sharpness: 10    Aberrations: 10    Bokeh: 10    Autofocus: 10    Handling: 9    Value: 9    New or Used: New    Camera Used: K5   

I have had this lens for a week and the following are just some of my observations and opinions. I am a bit of a "pixel peeper" thus was looking something that would be smaller than 16-50, give some flexibility and be SHARP!

My take on commonly debated points:
1. SIze: Yes, it is bigger. Get over it! It's an awesome lens, much smaller than any zoom with such IQ. And as it is so light, it doesn't weight down the front end so I forgot the size of it and treated it the same way as rest of my Limited's. People seem to forget that Limited's are incredibly small primes, this should be compared to zooms of equivalent IQ and it fares incredibly well in terms of size.
2. Aperture: At this size and IQ I am fine with the non-fixed aperture. If you want fixed aperture, set it to f4 and be happy If you want extreme aperture get FA 43 or A 50 f1.2
3. AF: Slouch? No, but it is slower than the rest of DA lenses. This is not an action lens, it is a lens where you take your time to compose the shot and AF is more of a helping hand so the slower speed doesn't bother me. I did not feel the need for it to be any faster at any point.
4. Zoom: People compare it's size to primes and zoom range to 16-50? Really? I see this lens as a "flexible prime". It gives the handling and IQ of a prime while allowing some flexibility, not much but some when changing lenses is too slow or a very bad idea.

1. Bokeh! This thing is wonderful, the rounded blades definitely do help. In comparison to FA 43 the bokeh of the background tree branches was a bit too nervous, but that is me splitting hairs already.
2. Sharpness. Mine is sharpest at 40mm, almost the same at 30 and a softer at 20mm. At f8 it has more resolution at any focal length than K5 "can handle", when wide open it softens up but only marginally. This thing gives the FA 43 run for its money and I personally think DA SMC 21 is on par with this thing in terms of IQ.
3. Build quality: The metal construction is sweet, it came to me as a surprise that the zoom ring is not metal, its rubber or plastic not sure, but very good quality one. I was not sure about the non-metal ring at first, but then realised that zooming all the time will rub the paint off the zoom ring and this thing will look...not so great. So now I think the non-metal ring is an awesome idea.
4. AF: Ouh, the sweet silence
6. WR: As it is new I am babying this thing, but friend of mine dropped a full cup of coffee over the lens and camera. Result? Wash under the tap and continue the walk Works like nothing happened and all good

1. Quickshift: Even though this lens has quickshift, the focus ring rotates when focusing and sometimes catches my fingers when doing that. Full time clutch like the one on other DA lenses would of been useful.
2. Hood: This thing is there for show and protect the front element. I think I will replace mine with 55-58 step-up ring and de-glassed filter to make a DIY hood and simple clip on cap. Just as useful and no drama when lost. Also makes the lens more wear proof as lens cap is usually first one to wear.
3. Price: This thing is expensive! I got a deal on it £200 off so was worth it, but at £850 it is just simply not worth the money!

In total this is a good addition to the Limited series and worth the money at around £650, not sure at £850 though. Incredible optics in a nice and small body
It's impossible to make a lens that satisfies everyone and every situation and I think comparing the zoom range to 16-50 and size to other Limited's is just non-sense. Zooms are always bigger and this one is small considering it's IQ.
Site Supporter

Registered: May, 2011
Location: Arlington, VA USA
Posts: 927
Lens Review Date: April 22, 2014 I can recommend this lens: Yes | Price: $900.00 | Rating: 10 

Pros: Excellent build, quiet fast focus and very good image quality
Cons: The lens hood

This is a lens you have to hold and feel, the quality is amazing, a welcome new addition to the Limited line up in my opinion. I admit with all the unfavorable discussion on this lens, I was a bit hesitant. Thankfully my local camera store had their semi annual sale and I was able to try for I buy. I was sold when I was using it. I have put the lens through its paces and I am very pleased. The sharpness is very good through out the range, very little distortion, and very quite focus. Focus is accurate and decisive. Blazing fast, no, but still fast. It also gets in pretty close for decent close ups!. Anyway, I can see this being my main lens for my URBEX photography as it lightens my gear a bit. I know the price is on the high side, but it is a well crafted lens that deserves a second look.
New Member

Registered: February, 2013
Posts: 14

2 users found this helpful
Lens Review Date: May 7, 2014 I can recommend this lens: Yes | Price: $1,300.00 | Rating: 10 

Pros: IQ, bokeh, build quality, WR
Cons: Not constant 2.8, not internal focusing
Sharpness: 10    Aberrations: 9    Bokeh: 10    Autofocus: 9    Handling: 10    Value: 9    New or Used: New    Camera Used: K-5   

Before this lens, my main lenses was DA*16-50 and DA*50-135, but usually I left the 16-50 at home. It was too big and I felt the pictures it produced varied too much in quality.
I bought this as soon as it came out and fell totally in love with it. It's been constantly on my camera ever since and I have no desire to remove it.

The "weired" zoom range, wich I was a bit afraid would turn me off, really doesnt bother me anymore.
I tend to threat it as a 30mm prime with "adjustment possibilities".

I've used it alot with extensiontubes, and it produces great macro results with the tubes. The transition between the sharp and the blurred, I find to be just lovely.
The only trouble I have is that I cannot access the menu on my K-5 with the extensiontubes and it refuses to go beyond f. 3.5. Wich is weired because all my other lenses communicate perfect with my camera through the extensiontubes. It might be the DC, it might be a software issues with the firmware. I don't know.

All in all I find this to be a great lens. It has reignited my interest in photography and cured my LBA. So now it's all about the pictures, instead of the gear, for me.

It might not be everyones cup of tea, but for me this is the gem I've been looking for (with a few minor flaws).

(Sorry for the bad grammar. English is not my mother tongue.)
Inactive Account

Registered: January, 2014
Posts: 76

1 user found this helpful
Lens Review Date: July 4, 2014 I can recommend this lens: No | Price: $1,060.00 | Rating: 6 

Pros: Built, Bokeh, design, WR
Cons: IQ, AF, hood
Sharpness: 7    Aberrations: 9    Bokeh: 10    Autofocus: 7    Handling: 10    Value: 6    New or Used: New    Camera Used: K-5ii   

This is my first pentax lens that I dislike.
First impression was very good. Lens is really nice piece of metal. Handling is very pleasant. But photos were lacking of something... And I didn't know what is not right. So I have done some testing (tripod, MUP...) between this DA20-40, DA L 18-55 Tamron 17-50 and DA18-135 and DA 35 AL. And that show, that this lens is really lack of sharpness! It isn't absolutely horrible, in fact it's quite mediocre - but for $1000 lens it is not acceptable. Kit lens has same IQ on 20mm as this lens, and my 18-135 is better! On 35mm is standing: Tamron, prime DA35 2.4, 18-135, DA-20-40, and kit lens. It has worse IQ thru all FL than my Tamron 17-50 and somewhere on par, somewhere worse than 18-135.

Autofocus is quite strange. Its quiet but not quick. My screwdrive lens are faster. And behavior of AF motor is like screwdrive, lik My other DC lens lock focus instantly, no need to microadjust, same on my SDM lens... And with multiple presses of AF button - multiple microadjustment - even on contrast scene.

What is good: This lens has very low CA, good flare resistance, nice built. And very, really very nice bokeh (maybe best for wide zoom that I ever seen). And it can handle images at higher ISO then others - I don't know how, but photos from this lens seems have less noise than photos from other lenses on same ISO.

Bottomline: I'm glad, that I had bought this lens from shop, where wasn't problem to return it and change it for another lens. But he had only one piece of 20-40, so I picked another lens. Maybe I'm just "lucky" for dud - but, apparently, I'm not alone.
Add Review of HD Pentax-DA 20-40mm F2.8-4 Limited DC WR Buy the HD Pentax-DA 20-40mm F2.8-4 Limited DC WR

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