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

Reviews Views Date of last review
52 211,317 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

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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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
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: 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.
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.
Site Supporter

Registered: February, 2012
Location: Adelaide Hills, South Australia
Posts: 9,250

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.
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.
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.
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