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

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

Sharpness 
 9.2
Aberrations 
 9.2
Bokeh 
 9.0
Autofocus 
 8.8
Handling 
 9.8
Value 
 8.8
Reviews Views Date of last review
59 246,115 Tue May 3, 2022
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Recommended By Average Price Average User Rating
93% of reviewers $709.90 9.20
HD Pentax-DA 20-40mm F2.8-4 Limited DC WR

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

Description:
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
© www.pentaxforums.com, sharable with attribution
Image Format
APS-C
Lens Mount
Pentax K
Aperture Ring
No
Diaphragm
Automatic, 9 blades (rounded)
Optics
9 elements, 8 groups
Mount Variant
KAF3
Check camera compatibility
Max. Aperture
F2.8-4
Min. Aperture
F22-32
Focusing
AF (in-lens motor)
DC
Quick-shift
Yes
Min. Focus
28 cm
Max. Magnification
0.2x
Filter Size
55 mm
Internal Focus
No
Field of View (Diag. / Horiz.)

APS-C: 39-70 ° / 33-62 °
Hood
MH-RA 55mm
Case
Soft pouch P70-150
Lens Cap
Metal push-on O-LW65A
Coating
HD,SP
Weather Sealing
Yes (WR)
Other Features
Diam x Length
71 x 68.5 mm (2.8 x 2.7 in.)
Weight
283 g (10 oz.)
Production Years
2013 to present (in production)
Pricing
$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)
Reviews
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
Notes
One aspherical element, one ED and one extra-low dispersion element.
No autofocus on older bodies (*istD series, K100D, K110D, and film).
Variants

Black and silver


Features:
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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Pentaxian

Registered: April, 2009
Location: Madrid, Spain
Posts: 9,001
Lens Review Date: May 3, 2022 I can recommend this lens: Yes | Price: $240.00 | Rating: 8 

 
Pros: Quite small, nice build quality, useful focal range, great image quality
Cons: Slow focus, focus accuracy, max aperture not super fast
Sharpness: 9    Aberrations: 9    Bokeh: 9    Autofocus: 9    Handling: 10    Value: 8    New or Used: Used    Camera Used: K-3   

This lens is taking more time than usual for me to really reach a conclusion and that's because it's a bit of an oddball with many things being neither here nor there - the focal range is short but useful, the maximum aperture is OK but not great, the focus is quiet but slow and not always accurate (at least my copy).

I have wanted this lens since it first came out as I have all the DA Limited primes and I love using them. A WR zoom that covers the most useful focal range with a decently fast max aperture and the feel and IQ of a Limited lens sounds great and I bought a used copy even though I already own the 16-85mm as a high quality WR option.

Image quality

Image quality is very good indeed. The lens is sharp wide open at all focal lengths, colour and contrast are typical DA Limited, flare is minimal and I haven't noticed any distortion. Though this lens isn't fast enough to be a real bokeh monster, the out-of-focus rendering is nice, especially wide open at 40mm.

Focal length

This is a short zoom that doesn't go as wide or long as even a kit lens and yet it covers focal lengths that are good for probably 90% of what I want to do. In practice I've found in the past that the DA 21mm is wide enough for most things so 20mm should be fine, and it is, but you'll probably want to have a wider option for when it's needed.

Aperture

f/2.8-4 is not particularly fast, especially at the long end and I can't help but feel that for the price and size it should really be a constant f/2.8 or even f/2.8-3.5. At 40mm and f/4 it's still possible to isolate close subjects and the other image quality factors still allow a nice 3D feel despite the modest aperture.

Size, build and handling

The build quality is typical of the DA Limiteds in that everything feels nice but it's also lightweight. The zoom ring is lovely and smooth. In fact it feels light enough to give the impression that a large proportion of it is empty space and the lens could probably be made more compact. The lens is pleasurable to use, more so than probably any other zoom I've tried, which is what I'd hoped for in a Limited.

Focusing

The focusing motor is nice and quiet but a little slow. With no fine-tuning my copy focuses perfectly at 20mm but is a bit off at 40mm and with this being a zoom, fine-tuning becomes a question of finding a setting that satisfies at both ends of the range, which is not easy. So far a change to -7 improves the results at 40mm while apparently leaving the 20mm untouched, which seems strange. I still need to play a little more with this though as it's not perfect at 40mm. Other people report that their copies are fine with no fine-tuning needed.

Summary

In summary, this is an excellent lens for walk-about use but many of it's limitations mean that there's almost always something better in terms of range or speed and at least equal in image quality. So what sets this lens apart? Why should you buy it? Well, I suppose it brings together a number of factors that you won't find elsewhere all together in a package that's this small and light. There's nothing that offers this image quality, range, speed, Limited build and pleasure of use all together in one package. However, as soon as you're willing to compromise on any one factor (size, weight, speed, IQ etc) there is immediately something that's better. That means that this lens is the best for what it is, but that niche is very narrow. In my case I'll keep it because there's no zoom this size and weight that I can enjoy using, and get such good results from, as much as a DA Limited. That makes it a great walk-around lens where there's no pressure to need anything wider, longer or faster, but if I do need to go outside of this lens's limitations then I'd take something else instead.

In the end I sold my copy but I could be tempted to get another in the future if I can find one that focuses properly at both ends of the focal range.


Baby feet
by Jonathan MacDonald, on Flickr


Madrid
by Jonathan MacDonald, on Flickr


Berries
by Jonathan MacDonald, on Flickr


Lost in the sand
by Jonathan MacDonald, on Flickr


Gijon
by Jonathan MacDonald, on Flickr


Posts and rope
by Jonathan MacDonald, on Flickr


Plastered
by Jonathan MacDonald, on Flickr


2021-07-29_01-26-12
by Jonathan MacDonald, on Flickr
   
New Member

Registered: January, 2022
Posts: 2

1 user found this helpful
Lens Review Date: January 18, 2022 I can recommend this lens: Yes | Price: N/A | Rating: 10 

 
Pros: Sharpness across the frame, fixed lens hood, exelent image quality
Cons:
Sharpness: 10    Aberrations: 10    Bokeh: 10    Autofocus: 8    Handling: 10    Value: 10    New or Used: New    Camera Used: K3 iii   

Direkt comparission with Da 16-85, HD 21 limited and HD 40 limited, the 20-40 winns in sharpness and overal rendering.


The 20-40 is extrem resistand against flare!
It outperforms my 21 limited and 40 limited.

Can´t understand the in- depth review....my copy is sharp from corner to corner 20mm and 40mm.

At f5.6 everything is better than my 21mm and 40mm limited

Bokeh is great.


all in all same league as my 50-135
   
Site Supporter

Registered: June, 2017
Location: 3City agglomeration
Posts: 1,165
Lens Review Date: November 18, 2021 I can recommend this lens: Yes | Price: $973.00 | Rating: 10 

 
Pros: Feel, build quality, image quality
Cons: lens cap, short focus throw
Sharpness: 10    Aberrations: 10    Bokeh: 8    Autofocus: 8    Handling: 10    Value: 10    New or Used: New    Camera Used: Pentax K-3 Mk III   

When I am using this lens I really feel as if I have pack of primes with me. I rarely use it like a zoom, just set up the focal length I feel at the moment and zoom with my feet. I think Pentax nailed this lens as Limited and being a zoom does not make it any less Limited then other Ltds. From all lenses I used till this time this one feels closest to old style manual lenses - both in look as in feel when operating.

Image quality is superb. I am not a pixel peeper so I will not say anything about aberrations and such - never noticed it on print or on screen. Frankly I don't care even if it sound not really photographic. There is no problem with using this lens in full sun or with artificial lightning shining from any side. Lens just delivers. It may be a walkaround lens for those not requiring long zoom range but still wanting something more elastic then prime. But it also works as "serious" lens for photographic projects etc. It is nicely paired with 15mm Ltd and I think with 70mm would make a perfect triplet.

Build quality leave almost nothing to be desired. It feels solid and sturdy, all lettering are clear, rings are easy to operate, but leave nice tactile feedback.

Cons? Two: for manual focus the focus ring throw is a bit too short. I would prefer something longer, but well, it is modern lens build with AF in mind. Second issue I have with it is lens cap. It is push on with material inside and after few months of use it already feels not as tight fitting as on beginning.

All in all - great lens, no regrets in getting it.

Here are some image samples:







   
Senior Member

Registered: June, 2021
Posts: 126

1 user found this helpful
Lens Review Date: October 2, 2021 I can recommend this lens: Yes | Price: $497.00 | Rating: 10 

 
Pros: Sharpness, Build, Motor is silent, Weather resistance
Cons: not fast enough after 22mm
Sharpness: 10    Aberrations: 10    Bokeh: 9    Autofocus: 9    Handling: 10    Value: 9    New or Used: New    Camera Used: KP   

A perfect walkaround lens on KP. The sharpness is impressive, even better than DA21 on the wide end. An all-in-one alternative to DA21 DA35 DA40 plus weather resistance and silent DC motor.
   
New Member

Registered: May, 2016
Posts: 20
Lens Review Date: March 6, 2021 I can recommend this lens: Yes | Price: $350.00 | Rating: 9 

 
Pros: Full Frame coverage better than expected, Center sharpness equals best primes
Cons: None
Sharpness: 9    Aberrations: 9    Bokeh: 9    Autofocus: 8    Handling: 9    Value: 9    New or Used: Used    Camera Used: K-1   

Just purchased this lens used, expecting to use it as an APS-C travel walk around and to replace primes on long hikes. The very first thing I did after unboxing was mount it on my K-1 to check full-frame coverage. Wow, was I ever surprised! Even at 20mm, there is a usable image (corners are black), and by 24mm, the corners are filled in with only mild vignetting! At 20mm, it's possible to crop a 2.5:1 panorama. The lens is very sharp, as sharp in the center as my FA 35mm f/2 AL, which is one of my sharpest lenses.

Given that the full frame coverage of this lens isn't often discussed, I thought I'd share a couple of sample photos (shot a few minutes after unboxing!). These are three exposure HDR images shot at f/8 (-2/0/+2) processed with Photomatix Pro - basically using the same process I would use for architectural photos (to assess how the lens would actually perform in my intended use). I think the full frame coverage is truly impressive, and is an important aspect for anyone who owns a K-1:

Full-frame image at 20mm - obviously vignetted, but also usable for cropped panorama



Full-frame image at 25mm, small amount of vignetting, correctable in post processing (Note that this amount of vignetting is less than many Sony 'Full Frame' lenses!):


Overall, I'm very impressed with the lens - basically flawless on APS-C, but maybe more importantly it also offers 'unadvertised' excellent performance on full frame.

Edit: It turns out that vignetting comes back at around 35mm when zooming, so the useful range on full frame with minimal vignetting is around 23mm-33mm. Still, once above 30mm, you're back to using the lens as intended, i.e. 20mm in APS-C crop mode. So on the K1, I will use as an APS-C crop 20-40mm lens (30-60mm effective), but switch to full frame to extend the usable wide angle range to between 23-30mm, and even down to 20mm for cropped panorama shots.
   
New Member

Registered: December, 2019
Posts: 7

4 users found this helpful
Lens Review Date: December 1, 2020 I can recommend this lens: Yes | Price: $497.00 | Rating: 9 

 
Pros: Build Quality, Color Render, Compact, WR
Cons: Curve of Field, Little Bit Soft Corner
Sharpness: 8    Aberrations: 7    Bokeh: 8    Autofocus: 7    Handling: 10    Value: 9    New or Used: New    Camera Used: KP   

Zoom range is narrow but weight is light and compact,and you'd like to take it outside for travel!
Color rendering is so beautiful, contrasty, and satruate.
Good for Travel, Street Snapshot, and Living style photo.

The Build Quality is awesome, all metal barrel just like the takumar lenses.
Trust me, it's a artcraft when you compare with plastic lens.

But the curve of field made the corner so soft, it is weak point, but just pay more attention for focus! It's fine!

Anyway, DA 20-40/2.8-4 Limited is wonderful lens, and I use it as my stardard zoom lens!



   
Forum Member

Registered: November, 2012
Location: Copenhagen, Denmark
Posts: 69

5 users found this helpful
Lens Review Date: November 29, 2020 I can recommend this lens: Yes | Price: N/A | Rating: 10 

 
Pros:
Cons:
Autofocus: 10    Handling: 10    Value: 10    New or Used: New    Camera Used: K-3   

The reviews and the evaluation of this new HD Pentax Limited zoom lens have been very different - some very negative and some very positive. I think that PentaxForums' test and evaluation of the lens is unfair with regard to sharpness (sample variation?). As soon as I received the lens I made some test footage, and I was admittedly a little confused about the results, but after some time I noticed an issue with back focus. It was subsequently adjusted to Back Focus + 5. Since then the results have been excellent. Back Focus + 5 was applied on two camera bodies (both K-3) with the same excellent result. The lens is sharp throughout the entire zoom range from 20 mm to 40 mm. I haven't noticed any decrease in picture quality in the long end of the zoom range. The color rendition is warm and very appealing - it can be compared with the DA *16-50 mm 2.8. The external parts of the lens are made of metal. I can highly recommend the lens. The reviews that have been negative may have forgotten that the lens is only one parameter of several in the process: photographer + camera/sensor + lens + image processing software + the photographer's ability to get all the qualities above. Lens quality is obviously very important - ultimately decisive, but so too the photographer's ability or skills. Thank you Ricoh/Pentax for this wonderful lens. It has lifted the pleasure of photography up to a higher level!
   
New Member

Registered: October, 2020
Posts: 4

3 users found this helpful
Lens Review Date: October 10, 2020 I can recommend this lens: Yes | Price: N/A | Rating: 9 

 
Pros: A stack of primes
Cons: A constant aperture would have been nice...
Sharpness: 9    Aberrations: 9    Bokeh: 10    Autofocus: 9    Handling: 9    Value: 10    New or Used: Used   

Hi Awesome Peeps

I am no pro here but I felt compelled to give my insights on this wonderful lens from a hobbyist's point of view.

Come to think of it for the value one gets for this lens it's like having the DA 21mm 35mm and 40mm Limited rolled into one. It's a bit faster than the DA 21mm at that focal. Slower than the DA 35mm and 40mm. One gets WR though in one stack of primes. Center sharpness is outstanding for a zoom through out its entire focal range. Stopping down to 6.3 onwards gives very good corner to corner sharpness. The nice bokeh it gives is a wonderful bonus. I find the colors lack a bit of warmth though at times but overall I am one happy boy when I shoot this lens.

I could not afford getting one but was able to swap some of my lenses for this. From a hobbyist's point of view this is one highly recommendable lens.

I've posted some shots. These won't win any awards but I just wanted to show how this lens renders. Cheers!!!



   
Site Supporter

Registered: July, 2020
Posts: 120
Lens Review Date: August 12, 2020 I can recommend this lens: Yes | Price: $528.00 | Rating: 8 

 
Pros: good build, appearance; light weight; compact size; optics
Cons: lens cap and thin hood; no aperture ring; manual focus only on my K10D without firmware update; not designed for FF cameras
Sharpness: 9    Aberrations: 8    Autofocus: 8    Handling: 7    Value: 7    New or Used: New    Camera Used: K10D, K-3 II   

Great little zoom lens, covering a good range for me. I wish they made this for FF cameras, to go with my forthcoming K-1 and my old LX cameras. It autofocuses well on my K-3 II camera, but I discovered after I bought the lens new that it won't autofocus with my K10D; this is only a minor problem to me because I like to manual focus. [I see on the "Notes" at the top of this review page that there is "No autofocus on older bodies (*istD series, K100D, K110D, and film)", and I presume this list includes the K10D, so I have only myself to blame for not researching enough. I just didn't consider the possibility that this lens would not autofocus with my K10D because my DA 12-24mm f/4 lens autofocuses well with it; my K10D works quite well, thank you. [After I posted this initially, three readers have pointed out that I need to update my K10D firmware through the Ricoh website, and then I should have autofocus ability with this lens -- good to know.]

The lens cap is maddening to use, as is the thin lens hood. The cap takes a good pull to take off, and I wonder what thousands of such pulls can possibly do to the lens zoom structural elements over time. Also, the lens cap only fits over the lens hood, so you have to have the lens hood on to have the lens cap on. There aren't many good lens caps out there, and I can imagine designers/engineers going crazy trying to develop what one would think would be a simple item to be practical and easy in use.

The lens hood has to be removed to put on a filter, and this is a huge problem because the hood is placed then on top of the filter threads, which means you turn the lens hood with the filter and can only turn it counterclockwise (as seen from the viewfinder) because turning it clockwise will loosen the hood and not give good turning motion on the filter. I also have difficulty with filters sitting too tight on the lens, making them very hard to remove. The screwing in of the lens hood onto my polarizing filter definitely has the effect of tightening the filter onto the lens, making it hard to pull off. I've played with this quite a bit and am convinced I'm doing nothing wrong. Just bad design for filters.

I haven't really looked at bokeh, so didn't rate it. The lens' optical sharpness seems very good, and the aberrations seem very slight for a zoom lens encompassing these focal lengths (I'm very impressed at 40mm, and at 20mm the distortion is minimal with not much vignetting). I don't see color problems. I used a resolution chart to test the lens (with K10D at ISO 100 in direct sunlight) for sharpness and distortion at 20, 30, and 40 mm, and at f/2.8, f/3.5, and f/4.0 wide open (respectively), up to f/22, and the sharpness and lack of distortion is excellent -- even at 20mm. The sharpness improves at f/8 over wide open, but the wide-open sharpness is good for most purposes. The narrow focal-length zoom ring does its job, turning about 60 degrees to the left (counter-clockwise, as seen from behind the camera) from 40 to 20 mm; good design, with no possibility of "zoom creep" when pointing up or down. The filter does not rotate when the lens is focused or zoomed. The thin manual focusing ring turns about 90 degrees from infinity (also counter-clockwise as viewed from behind the camera) to closest focus, and it's not as good as typical manual focusing rings on older (pre-F-series) Pentax lenses, but it's adequate.

For me, the lens is over-priced (my listed price above includes sales tax, as bought from B&H with free shipping). But in terms of the optical quality, it seems impressive indeed, and worthy of being in the Limited family. I will keep it and probably use it a lot on my K-3 II cameras (though in practice, it has not come close to replacing my DA 12-24mm lens as my standard walkaround lens on my APS-C cameras, as I thought it might when I ordered it).

Below are photos showing the lens on my camera:


   
New Member

Registered: November, 2018
Location: Tokyo
Posts: 10
Lens Review Date: June 13, 2020 I can recommend this lens: Yes | Price: $420.00 | Rating: 10 

 
Pros:
Cons:
Sharpness: 9    Aberrations: 9    Bokeh: 10    Autofocus: 10    Handling: 10    Value: 9    New or Used: Used    Camera Used: KP   

The lens you can attach to your camera all day and take quality images. Sometimes wants some wider f stop but for the size I cannot complain.
   
Pentaxian

Registered: December, 2007
Location: Pacific Northwest
Posts: 306
Lens Review Date: May 3, 2020 I can recommend this lens: Yes | Price: $497.00 | Rating: 10 

 
Pros: Sharp, compact, excellent flare resistance, great build quality
Cons: Slight field curvature - requires careful focusing for best results
Sharpness: 9    Aberrations: 9    Bokeh: 9    Autofocus: 9    Handling: 10    Value: 10    New or Used: New    Camera Used: K-70   

This is a great little lens. When it first came out I wasn't interested, because most of the reviews from the major review sites were underwhelming. But as reviews from actual users started to accumulate I noticed that they were almost universally positive. Could all of these users be wrong? I decided to take a chance, and grabbed one when it went on sale. I am glad that I did. The lens is very sharp, it is a joy to handle, and it has great build quality. It also has excellent flare resistance--not just for a zoom, but for any lens.

The lens does suffer from a small amount of field curvature, so very careful focusing is required to get optimal results across the frame. Once you learn the optimal focus points it is extremely sharp across the frame (when stopped down). This, combined its small size and great flare resistance, makes it ideal for travel photography.

While the range of focal lengths seems a bit narrow, I find it to be a very useful range. I have a wide range of lenses, from 8mm to 400mm. But I noticed that about 90% of my photos are taken with lenses in the 20mm to 40mm range, so the range of this lens suits me just fine.

The lens is a real gem!
   
Site Supporter

Registered: January, 2013
Location: Ottawa, Canada
Posts: 3,558

8 users found this helpful
Lens Review Date: April 10, 2020 I can recommend this lens: Yes | Price: $500.00 | Rating: 9 

 
Pros: Compact, Lightweight, Excellent Image Quality, Weather Resistance, Design and Construction
Cons: AF Fine Adjustment on my K-3 II (see below)
Sharpness: 9    Aberrations: 9    Bokeh: 8    Autofocus: 8    Handling: 10    Value: 9    New or Used: New    Camera Used: Pentax K-3 II   

Why I acquired this lens
Although I’ve used my DA 18-135mm lens extensively for several years, I have not been entirely happy with it. I had purchased it mainly for the shorter half of its focal length range (i.e., 18-50mm), and treated the longer telephoto reach as a bonus. The 18-135 is fairly sharp between 20 and 60mm when stopped down, and it’s a versatile ‘walk-about’ or travel lens, as many users attest. However, I find its inherent contrast to be relatively weak; the bokeh is often not as pleasing as I’d like; the corners can be mushy or softer than in comparable images from some of my other lenses; and I've never seen any ‘pop’ or ‘dazzle’ in my pictures. Occasionally, I've missed having a wider aperture. In searching for a replacement zoom, I considered the Sigma 17-50 f/2.8, the Pentax DA 16-85, and other possible options. I wanted a weather-resistant lens and something that would compare well to my DA Limited lenses in terms of image quality. The DA 20-40mm Limited fit my needs.

Design, Construction, and Handling
In my opinion, the HD Pentax-DA 20-40mm Limited features a refined design and solid construction. Taking cues from the classic S-M-C Takumar line, of which I have several models, this lens is a handsome impression of simplicity and elegant appearance, perfectly complementing the other lenses of the DA Limited series.

On my copy, the zoom action is smooth yet sufficiently tight, while the lens also affords a perfectly usable, slightly-damped manual focus movement with a finely-ribbed ring at its front. The general construction seems to be tight. Although it’s not overly heavy at nearly 300 grams, this compact lens has a certain heft for its size that hints at its metal-and-glass construction.

The lens is handled easily and securely, fitting in the palm of my hand, and it fits readily in any of my camera bags. The slip-on lens cap still fits tightly after a year of use, although the flocked interior of the cap tends to attract dust over time. The included lens hood appears to be relatively shallow, but I haven’t observed any instances where it has failed to provide adequate shading.

Autofocus
I tend to take pictures mainly of static subjects with this lens, and I find that the autofocus is sufficiently quick on my K-3 II. As I have done with my other lenses, I conducted a rigorous AF Fine Adjustment (AFFA) for my DA 20-40, assessing the settings at 20, 30, and 40mm; at focus distances of at least 60 x FL; and variably focusing from the minimum focus distance and infinity positions. I found that the optimal AFFA calibration at 20mm is significantly different from that at 30mm and 40mm; the only setting that gives the sharpest autofocus at all focal lengths is AFFA = +2 when focused from infinity. So, I simply preset the focus to infinity before each shot, which is not a big deal, but this detail is reflected in my lower rating of ‘8’ for AF. Note, however, that the AFFA is a function of both the lens and the camera acting together, so this issue may not be entirely a fault of the lens itself.

Update 30 July 2021: AF calibration on K-3 Mark III. The variation of optimal AFFA settings is less pronounced on my K-3 Mark III. Acceptable sharp focus is obtained at all focal lengths when focusing from the far or near focus positions. AFFA = -4.

The AF accuracy and shot-to-shot consistency are very good, which might suggest that the lens is constructed to tight mechanical tolerances and its in-lens AF motor is a good match.

Optical Quality
Here are my subjective observations, based on many images that I've taken with this lens. My copy is fairly sharp across the field at almost all focal lengths and aperture settings, although not as sharp at the corners at wide-open apertures. In my typical usage, I have no concerns with edge and corner softness; in fact, I am often pleasantly surprised at its good corner performance, especially compared to my DA 18-135. I’ve not noticed any serious field curvature effects, which a few other users have reported.

Its excellent colour, contrast, and overall image rendering are similar to my DA Limited primes. The out-of-focus areas exhibit pleasing bokeh most of the time, although not as smoothly as, say, my DA* 50-135mm. The lens seems to resists flare and ghosting very well.

The apparent vignetting at the widest apertures and geometrical distortions are corrected easily either in camera or in post processing (I use RawTherapee’s lens profiles), as are the minor aberrations. I’ve taken advantage of the relatively short minimum focus distance of 28 cm, especially when shooting wide open at 20mm.

Versatility, Comparisons, and Value
In short, I find the DA 20-40 to be an excellent lightweight zoom. I have used it in a variety of settings, including classic car shows, trail hikes, and city walks. I often carry it in a two-lens kit with the DA* 50-135, or sometimes three lenses adding the wide-angle DA 15mm Limited or FA 43mm Limited if I need a faster lens. While the zoom range is modest, it has a useful range on either side of ‘normal’, which provides a surprising degree of versatility. I’ve used this lens instead of carrying both the DA 21 and DA 35 Limiteds; I’ve not noticed any practical penalty in image quality although I have not compared these lenses rigorously.

As with other lenses, this one has pros, cons, and trade-offs. Compared to my DA 18-135, for example, I think the image quality is definitely better with my DA 20-40, but at the expense of less reach (hence, I may also carry my DA* 50-135). One might opt for the DA 16-85 – a good lens in its own right – but at the expense of slower apertures at the common focal lengths; a 60% heavier lens; a larger filter diameter; and perhaps an inferior manual focus action. The affordable Sigma 17-50mm is praised by many users; however, it’s not weather resistant and is significantly heavier and bulkier. The 20-40's widest aperture of f/4 at 40mm is perhaps a notable disadvantage, but that's a trade-off against lens size and mass.

When the DA 20-40 appeared on the market, I balked at its introductory price of CAD $1000, and acquired the DA 18-135 instead at $450. When the Limited zoom was offered eventually in Canada for CAD $725 (~ USD $500), the price was more palatable and I had saved up some funds in my ‘camera kitty’ so I jumped at it.


Conclusion
Overall, I find that the lens is a joy to use and it produces wonderful images with beautiful colour, high contrast, and 'depth'. It's one of my most-used lenses.


- Craig

   
Site Supporter

Registered: December, 2007
Posts: 1,128
Lens Review Date: January 5, 2020 I can recommend this lens: Yes | Price: N/A | Rating: 9 

 
Pros: Look, finish, convenience
Cons: Filter size vs other limiteds
New or Used: New   

Have wanted this lens for quite a while in chrome to go with my K-3. Borrowed a friend’s copy last year and found it very usable on my K-1 from 24mm on and by using a 16x9 crop usable down to 20mm. So when the it went on sale prior to black friday, pulled the trigger. Below is cropped monochrome image at 40mm with my K-3
   
Senior Member

Registered: September, 2009
Location: Wisconsin
Posts: 156
Lens Review Date: December 30, 2019 I can recommend this lens: No | Price: $399.00 | Rating: 6 

 
Pros: build quality
Cons: limited range
Sharpness: 8    Aberrations: 8    Bokeh: 5    Autofocus: 7    Handling: 8    Value: 4    New or Used: Used    Camera Used: K-01   

Look, its a fine lens, its beautiful, and its...fine. I don't love this lens, which is a rare thing to say with a Limited, especially for me and a DA Limited. I have a 40mm HD, and a 70mm HD, and those two primes I absolutely adore. This lens I got because I got a deal, and I couldn't justify spending the same for a 21mm I would have gotten to fulfill the prime set for my light bag. I guess I wish they would have thought about a few things - I rather this lens was a 15-35 because I feel unlike my 16-50 DA*, the range just isn't wide enough (one of the two complaints with my 24-70) and yet it doesn't reach very far on the other. I get that this is a Limited, and the history for Pentax is these are not standard ranges (having a 77 and 43). It just is a pretty face, and good quality lens, but it does nothing extraordinary like my other lenses.
   
Senior Member

Registered: June, 2011
Location: Rotterdam, Netherlands
Posts: 235

3 users found this helpful
Lens Review Date: December 19, 2019 I can recommend this lens: Yes | Price: $600.00 | Rating: 9 

 
Pros: build quality, WR, 3D Pop, compact
Cons: needs stopping down for corner to corner sharpness
Sharpness: 8    Aberrations: 9    Bokeh: 8    Autofocus: 8    Handling: 10    Value: 10    New or Used: Used    Camera Used: Pentax K-5   

Before acquiring this lens I mostly shot with high quality vintage primes on my K5. That spoiled me when it comes to sharpness ... but I was really starting to long for auto-focus and didn't want to move back to the kit-lens. I found this gem on Ebay and loved it from day 1.

Initially I was a bit worried about the limited () zoom range, but I discovered that 20-40 works well for me. This is now my #1 walk-around and travel lens. It feels like a modern Takumar. To have WR is great and the images have a very nice '3D pop'. It's definitely not a sharpness monster and needs some stopping down, but I don't need that. It just creates gorgeous looking pictures and is a joy for every day use.

Sample shot (36mm, F4, 1/2000):

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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