[lytrytyr]

A useful if skeptical review is now up on Optyczne (but not yet Lenstip):

Test Pentax HD DA 20-40 mm f/2.8-4.0 ED Limited DC WR - Wst

[Frater]

This review is now available in English at LensTip.com:
Pentax HD DA 20-40 mm f/2.8-4.0 ED Limited DC WR review - Introduction - Lenstip.com


In short, it is a F8.0 lens, because the edge resolution is getting worse wider open quickly, until "The image quality in the area near the maximum relative aperture is weak".


At F8.0 it seems near to my Kit (18-55 II), except at the short end's edge area, where it is better. That's decent, given that it doesn't have an aspherical element AFAIK

On the "Coma, astigmatism and bokeh" section, the 18-55 II seems to have better defintion and compactness of the LED light in the corner. That MAY suggest, that the 20-40 has a resolution drop between the edge and the corner, which doesn't show off in the resolution chart (because they measure edge resolution rather than corner resolution there).


They praise the 20-40 for its ghosting and flares performance.
The 18-55 II seems to have better contrast rendition, in terms of deeper dark tones (as far as the different pictures can reveal?), where the 20-40 looks pretty washed-out. But the 20-40 doesn't produce ghosting bubbles, where the kit lets at least one bubble sneaking in more easily.


For me, I'm not upgrading from my 18-55 II kit to the 20-40 (unless its price would be line with the Tamron 17-50, which has a different mix of advantages/disadvantages of course).

[gazonk]

In short, it is a F8.0 lens, because the edge resolution is getting worse wider open quickly, until "The image quality in the area near the maximum relative aperture is weak".

Hmm. Quite disappointing. I think I just decided to reconsider the DA21 to fill in the gap between the DA15 and the DA35. I was thinking of buying the 20-40 instead, but I think I'll be better off using my old 16-45 when I need a zoom in that range.

[Na Horuk]

But didn't a member post landscape photos taken with this lens and the 16-50mm? And those samples showed the 20-40mm had better edge performance

[lytrytyr]

In short, it is a F8.0 lens, because the edge resolution is getting worse wider open quickly, until "The image quality in the area near the maximum relative aperture is weak".

If your only criterion is edge-to-edge sharpness, you would be better served by the Tamron 17-50.
The central sharpness of the DA 20-40 is high (over 40 lp/mm) at all apertures until diffraction sets in.

At F8.0 it seems near to my Kit (18-55 II), except at the short end's edge area, where it is better. That's decent, given that it doesn't have an aspherical element AFAIK

Although the lens' designation does not include "AL",
there is an aspherical element.

On the "Coma, astigmatism and bokeh" section, the 18-55 II seems to have better defintion and compactness of the LED light in the corner. That MAY suggest, that the 20-40 has a resolution drop between the edge and the corner, which doesn't show off in the resolution chart (because they measure edge resolution rather than corner resolution there).

According to this argument, your kit lens would be better that the FA 31,
whose coma appears to be more severe than that exhibited by the DA 20-40.

The 18-55 II seems to have better contrast rendition, in terms of deeper dark tones (as far as the different pictures can reveal?), where the 20-40 looks pretty washed-out.

This depends on the processing.
I have found the rendering of the DA 20-40 to be excellent,
leagues away from the muddy rendering of the kit lens.

For me, I'm not upgrading from my 18-55 II kit to the 20-40 (unless its price would be line with the Tamron 17-50, which has a different mix of advantages/disadvantages of course).

The Limited lenses are not for everyone.
Personally, I like this lens better than my Tamron 17-50,
but your criteria may well be completely different.
Fortunately, most of us have a choice of which lenses we can mount on our cameras.

[Zygonyx]

Very unfortunate to see bad reviews for this lens, visibly not corresponding to users experience returns... and focussing on "edge to edge sharpness".

I seems pixel-peepers are now ruling lenses fate.

[lytrytyr]

I[t] seems pixel-peepers are now ruling lenses fate.

They will be condemned to lugging around a Sigma 18-35!

[gazonk]

Very unfortunate to see bad reviews for this lens, visibly not corresponding to users experience returns... and focussing on "edge to edge sharpness".

I seems pixel-peepers are now ruling lenses fate.

I'd love to see some side by side shots of this lens and e.g. the 16-45. I don't doubt that it's much better than the 18-55, which IMHO mostly gives a very boring look.

[H. Sapiens]

They will be condemned to lugging around a Sigma 18-35!

They won't worry, since it will only be from the office to the lab. I suspect many lens testers don't get out shooting pictures in the real world much.

I have a couple of times tried to search for images from some of the testers used by magazines in my country and nothing showed up. Even this forum shows that we have different interests: I couldn't be bothered doing tests but would rather spend time going to an exhibition. I often feel the majority here would choose the other way around.

That said, I need to see some really convincing real world reports with images from this lens. At first I was really interested, but my enthusiasm have cooled

[Frater]

I'd love to see some side by side shots of this lens and e.g. the 16-45. I don't doubt that it's much better than the 18-55, which IMHO mostly gives a very boring look.

Hi Gazonk, that makes me curious. I only have the 40mm (my only Limited), to compare my Kit against at 40mm, but didn't recognise any "boredom gap" between them.

But if you do see a gap towards your 16-45, then that one must be an interesting lens for me to consider as an upgrading target? What visual criteria is your "boredom" criteria?

I suspect that you are hooked on bokeh, because I can confirm that the Kit's bokeh is indeed nothing special really, i.e. indeed somewhat boring

[gazonk]

Hi Gazonk, that makes me curious. I only have the 40mm (my only Limited), to compare my Kit against at 40mm, but didn't recognise any "boredom gap" between them.

But if you do see a gap towards your 16-45, then that one must be an interesting lens for me to consider as an upgrading target? What visual criteria is your "boredom" criteria?

I suspect that you are hooked on bokeh, because I can confirm that the Kit's bokeh is indeed nothing special really, i.e. indeed somewhat boring

I'm not sure if I can pinpoint it, I haven't used the 18-55 much (I gave the 18-55wr that came with my K-5 to my youngest son together with the K10d). I actually think the 18-55 often works good at the long end (my daughter has taken some nice portraits with it), but at the wide end, it often seems "murky" to me, I think the 16-45 has better clarity, color, micro contrast.

[lytrytyr]

That said, I need to see some really convincing real world reports with images from this lens.

We've started a "lens club" for it:

https://www.pentaxforums.com/forums/122-lens-clubs/247859-da-limited-zoom-club.html

One of the images posted there may really discourage you,
but I believe that it was taken with one of the earlier "beta" versions of the lens.

The serial number of the copy used for the PF review (9603201)
is out of sequence with the copies that have received better reviews,
e.g. 9600338 on Optyczne/Lenstip, or 9600243 on ePHOTOzine.

[Mistral75]

We've started a "lens club" for it:

https://www.pentaxforums.com/forums/122-lens-clubs/247859-da-limited-zoom-club.html

One of the images posted there may really discourage you,
but I believe that it was taken with one of the earlier "beta" versions of the lens.

The serial number of the copy used for the PF review (9603201)
is out of sequence with the copies that have received better reviews,
e.g. 9600338 on Optyczne/Lenstip, or 9600243 on ePHOTOzine.

I am not so sure serial numbers at Pentax mean anything in terms of manufacturing date or even manufacturing batch.

[thibs]

I am not so sure serial numbers at Pentax mean anything in terms of manufacturing date or even manufacturing batch.

But may still be an interesting clue to a possible explanation.

[Digitalis]

Although the lens' designation does not include "AL", there is an aspherical element.

No, there isn't - I looked at the optical construction of it the 20-40mm and like the FA77 there are no aspherical elements used in its construction.