[pakinjapan]

I have F28 f2.8 lens and I really like its sharpness, size and color. I used to have FA20, F28, FA35. While I like the sharpness of 28 and 35 but I like 20 mm focal length a lot more, and It was enough for me to try to sale both 28 and 35. Unfortunately my 20 broken soon after I sold 35 so I get to keep the 28 until now.

Now with an upcoming trip I know I can do it with F28 and I will be happy with its image quality. (as always) but I still very much miss 20 mm focal length. I prefer to carry one very good and compact lens on a trip. So I am looking at either DA21 or DA 20-40.

DA21 can produce lovely starbursts effect. (a huge plus point)
DA20-40, it is a WR lens which is what I want to have for a travel lens. I could also get away with changing lenses. (2 big plus points here but not a must). I go out almost every weekend for night photo shooting in Tokyo and whenever I have 28mm on, I often find myself want to try the same scene with 50 mm. I end up switch btw the 2 all the time. And when I am on a trip with 28mm only, I often miss my 50. It has never happened when I use 20 mm alone. (I know it’s weird.)


I wonder if;

1. General speaking, Does sharpness on DA21 on par with F28 (or any sharp 28mm)?
2. What about DA21 vs FA20 sharpness?
3. And 20-40 sharpness (at 20, and around 28-35 mm) vs F28 (or any sharp 28 mm)?
4. Can 20-40 produce nice looking starburst effect at around 20-28 mm? I might be wrong but from looking at image online, I would say my F28 starburst doesn’t look bad at all when compare to 20-40 but still lightyear behind the 21.
5. If you are me, own a sharp and relatively fast 28mm, would you sale it for either 21 or 20-40? If so, which one would you go for?

Please feel free to voice in your opinion. Any input will be appreciated.

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Last edited by pakinjapan; 02-21-2017 at 05:43 PM.

[jddwoods]

I have both the SMC DA 21 Limited and the F 28mm f2.8.I use both for landscapes and close-ups. Overall I would say the DA 21 is slightly sharper than the F 28mm. It is also much more resistant to flare in sunny conditions than the F 28mm. That is my response to your #1 I can't answer 2 through 4 but if you get the DA 21 Limited, I would still keep the F 28. Its full frame in case you decide to go that route in the future. Both are very small and light.

[mattt]

FoV is not comparable. On APS-C a 28mm is a "normal" lens while the 21 or 20 is a wide angle. Having owned both, my preference is the 21 for travel / street shooting. Great colour, plenty sharp - and even with a hood very compact. The 20-40 is not compact in the same way but brings other things to the table.

[Marktax]

My 20-40 at 20mm/f2.8 is sharper at the edges than my 21 at f3.2.

[caliscouser]

I think the 20-40 gives you everything you want except starbursts. Tough call, how important are they to you, a deal-breaker?

Of course if you go the 21 route you'll want the SMC version (for starbursts) and not the HD version.

[photogem]

I have compared the DA20-40 with the DA21, DA35, DA40 and others and I love it. On walks it sits on my K5IIs, my only zoom. Plus it is quiet.

My findings compared to the DA21 and DA40:

pro DA20-40 versus DA21:

- sharper than the DA21
- F2,8 at 20mm (DA21 is 3.2)
- DC ultraquiet focus
- WR

pro DA21:

- starbursts (smc only but I don't care about them anyway)
- better colours for photos of water (an amazing lens for water)
- smaller, lighter (doesn't matter, the DA20-40 is well balanced on the K5IIs)
- fullframe 24-40 (DA21 not for fullframe!)

pro DA20-40 versus DA40:

- same quality but WR
- ultraquiet DC motor


pro DA40:

- smaller
- starbursts (smc version only)
- fullframe

I have kept the DA40 because I like it on my K-01 with the DA15 for very light travelling and it works well enough for video.

addition, I almost forgot:

contra DA21 early smc version:

- some DA21s developed a loose hecoid retainer ring which caused off-focus (infinity).
My DA21 never had that problem so I was lucky as I used it a lot then.

But if starbursts are what you are after I would say go and get the SMC version and then chose which lenses
to accompany it. Maybe even an FA43? Needs to be mastered though. Or in different words:
Shots with the DA40 work out, with the FA43 you might find yourself in an interesting learning process.

[Jacquot]

I have both lenses, and the 20-40 lives on my K-3. I only change it out if I have a particular reason to use another lens. As far as digital zooms go, it is pretty compact. I agree with the comments of others as to the differences.

[Nick Siebers]

My experience with the DA 20-40 vs. the 21 has been similar to what photogem describes. I no longer own a 21, the DA 20-40 is quite good at that range. Both are better than the FA28, in my experience.

[bdery]

DA21 can produce lovely starbursts effect. (a huge plus point)

It is its main perk. That's why for the time being I'm keeping mine even though I shoot full frame now. (I assume you're speaking about the SMC version, since the HD version has curved aperture blades and does not produce the same starbursts).

General speaking, Does sharpness on DA21 on par with F28 (or any sharp 28mm)?

The DA21 will be a bit sharper than the F28, similar to the FA28.

What about DA21 vs FA20 sharpness?

No opinion.

And 20-40 sharpness (at 20, and around 28-35 mm) vs F28 (or any sharp 28 mm)?

Regarding only sharpness, the 20-40 will be in the same league as the DA21

Can 20-40 produce nice looking starburst effect at around 20-28 mm?

No it cannot.

If you are me, own a sharp and relatively fast 28mm, would you sale it for either 21 or 20-40? If so, which one would you go for?

For night city photography, the SMC DA21 is a no-brainer. It's probably the best night photography lens Pentax ever produced (along with the DA15, which is harder to use). I've been looking for a full frame equivalent and have not found any. To get close to the results of the 21 at F4.5 with the F28, you need to go to F16.

An example of the DA21 at F4.5:



Another, just because:

[Blacknight659]

I own the 20-40 and love it. I'll have to test the starburst effect and get back to you. I usually use the 15mm for this, but I can give it a go and get back to you.

I can tell you my previous night photos didn't produce the effect very well, I believe there are rounded blades in there preventing the Star

[photogem]

I wrote once about my experiences of some of my favorite lenses in another thread, lenses in 35-43mm range.
Things have changed since then, I own a Zeiss Distagon *T35F2 (fantastic micro-contrast/micro-dynamics), the FA31 (another queen of aquarell-like painings, but very different to the FA43) and then Takumars.
But to cut the story short, this is the link:
DA 40mm vs FA 43mm - Page 7 - PentaxForums.com

I sold the FA35/2 but kept the A35/2.

But most important: the DA20-40 is an amazing lens!
I would not part with it. It is a shame it only works fullframe from 24mm on.

Another lens below 28mm that I remember well is the Exakta 24mm (Ricoh PK/A, pin easely taken off).
Has close-up abilities and is very good. Usually very cheap, I call it the poor man's DA21 limited.

If 24mm is enough and AF not important, possibly an interesting addition.
But I just don't know about starbursts.

I am 99% sure, it is identical with this one:
Cosina 24mm f/2.8 MC MACRO Lens Reviews - Cosina Lenses - Pentax Lens Review Database

[northcoastgreg]

If you are me, own a sharp and relatively fast 28mm, would you sale it for either 21 or 20-40? If so, which one would you go for?

It depends at least in part on other lenses one might own. For example, I already own an FA 20-35 (very good on APS-C, nearly as sharp as the limiteds and great color) and the DA 16-85 (nearly as sharp as the limiteds as well). Owning those zooms, I chose the DA 21 over the DA 20-40. If it didn't own those zooms I might have taken the DA 20-40 (I love compact high quality zoom lenses) over the DA 21. I would also definitely take the DA 21 over any 28mm lens you'd put against it, just because of a preference for the 21mm focal length.

One thing to be aware of about the DA 21: it's not designed to be super sharp wide open. So if that's what you're looking for, the DA 21 may end up disappointing you. I'm not a wide open shooter, so it's not an issue with me. Indeed, I prefer a lens that "soft" wide open because it will likely feature less glass and probably be more flare resistant. The DA 21 is quite sharp stopped down with very good flare resistance and excellent contrast.

[bdery]

But most important: the DA20-40 is an amazing lens!
I would not part with it. It is a shame it only works fullframe from 24mm on.

I would love for Pentax to make a 20-40 FF lens.

[Rico]

bdery, The SMC-Pentax-F-24-50mm-F4-Zoom-Lens.html is something Pentax could model it on.

It is a hard call to say either or. For traveling light and convenience you can not beat the DA 20-40 LTD for APS-C. But I can see the desire to have the compactness of the DA21. So the long term plan would be to own both. In the short term for the use of traveling the DA 20-40 really offers more. Not having to switch out lenses. WR. Which means weather really isn't a factor. Overcast conditions often are a good time to photograph street scenes as the light is very even.

I don't think the OP would be disappointed with the DA 20-40LTD. The DA 21 and DA 40 prices can be nicely discounted at times which make these lenses more affordable over the long term.

[bdery]

bdery, The SMC-Pentax-F-24-50mm-F4-Zoom-Lens.html is something Pentax could model it on.

I'd like that. Though I think that design is "ok", not "superb". It would probably be better to start back from scratch.

Not having to switch out lenses. WR.

WR Limiteds would make me spend a lot of money

Not having to switch lenses is what made me decide on the 16-85 instead of the 20-40, as much as I like its size and looks.