[6BQ5]

How does the DA 21 stand up against the DA 18-135 zoom at the same focal length? Is there a significant boost in IQ from using the DA 21 over the DA 18-135?

[mtux]

If you mean sharpness, around 24mm is where DA18-135 is great. Though still DA21 manages to be little sharper on corners for pixel peepers, and have more micro contrast as expected from a prime.
If you mean colors and overall IQ, I prefer my DA21 over the zoom. (Even though I didn't notice this for a long time when I purchased the DA21 and had them together!)

---------- Post added 01-14-15 at 12:28 PM ----------

Here was the first time I noticed the difference! when I used both of them at the same scene.
both had a polarizer on. (Same brand, different thread size)
https://www.pentaxforums.com/forums/12-post-your-photos/253025-nature-some-waterfall-shots.html

[lesmore49]

I've got both and like both. I don't notice huge differences...but then I rarely enlarge past 8 X 10.

[kh1234567890]

Here was the first time I noticed the difference! when I used both of them at the same scene.
both had a polarizer on. (Same brand, different thread size)
https://www.pentaxforums.com/forums/12-post-your-photos/253025-nature-some-waterfall-shots.html

It is hard to tell anything from oversharpened and downscaled shots with a watermark blatted over them ...

[Al_Kahollick]

Not to mention that they're not the same scene, the same waterfall perhaps, but different parts of it in each photo!

[GeneV]

The biggest difference you are likely to see is if you use the lens wide open. The DA 21, like the other ltd lenses, does pretty well at max aperture. The DA 18-135, like most of the kit lenses, needs some stopping down. The reality is that in most scenes where corner sharpness matters, you need stopping down anyway.

[mtux]

It is hard to tell anything from oversharpened and downscaled shots with a watermark blatted over them ...

I was talking about colors with regard to those shots, and I remember that time I went back to them and tried to make the colors the same, but I wasn't able to.

[formercanuck]

I guess part of that question would be...

a) what f stop
b) in real world or against a chart
c) across the whole lens ? Probably more so at the corners with a prime.

Looking at the review of the DA-21 vs. 18-55mm WR and Sigma 17-70, it is sharper, but it all depends I guess on what you're shooting . For me, as I have an 18-135mm WR and a 28mm f/2.8, it really depends on what I'm shooting to what I'm going to use. If I'm shooting landscape or something that I can take my time to compose - I'll pick the prime. When I'm walking about - I'll be using the 18-135mm for convenience and in my case - AF

Review: Pentax-DA 21mm F3.2 - Introduction | PentaxForums.com Reviews

[Nicolas06]

The 18-135 is really at its best arround 24mm. 21mm should be quite good too.

I would say the DA21 will get for sure better flare resistance, a bit better micro contrast/colors to be checked...

This not the lense where you'll see the most difference... Compare with a DA50-135 or FA77 and here it will be night and day.

I have a DA21 because it is soo small. Because the hood is included and protect the lense perfectly while being as small as it get. The focal length allow one to go very far and can do a lot with just the DA21 onboard.

DA21 & FA77 are the 2 lenses I use most and they mostly replace for me the whole 18-135... And the FA77 is not just about subtle micro contrast difference. The lense is sharp and open wide... On top of offering a great 3D look.

[TER-OR]

I have both but have never made any formal comparison. I can say the images I've taken along the river with the DA21 are very good, with great contrast. It is a pleasure to use.

[Blacknight659]

I would expect more distortion from the 18-135. Also, the 21mm should be a bit sharper with better contrast.

Other than this... you have the physical differences which are obvious.

Both are wonderful!

[Parallax]

I was talking about colors with regard to those shots,

That's what jumped out at me. The color rendering of the 21 is remarkably better in this scene.

[6BQ5]

Thanks to everyone for their replies! I have been clicking through test data plots and looking at image samples. Seems like every good lens can sing a fine tune when used in the right hands. I have seen some exquisite samples from the DA 21 and the DA 18-135 is no slouch either. Maybe the difference is measurable but noticeable only in certain situations.

@mtux - Your images of the waterfall from both lenses looked very nice!

I am fortunate to have the three FA Ltds and the FA 50 f/1.4. My hidden thought was that the DA 21 could compliment them and out-do the DA 18-135mm as a WA lens. Now I'm thinking that I might be better served by the DA 15. The DA 12-24 zoom sounds appealing but it's expensive and only works on APS. The Sigma 12-24 cheaper and FF but the images samples make me feel bipolar. But, all of that is for another thread!

[vrolok]

I am fortunate to have the three FA Ltds and the FA 50 f/1.4. My hidden thought was that the DA 21 could compliment them and out-do the DA 18-135mm as a WA lens. Now I'm thinking that I might be better served by the DA 15. The DA 12-24 zoom sounds appealing but it's expensive and only works on APS. The Sigma 12-24 cheaper and FF but the images samples make me feel bipolar. But, all of that is for another thread!

My WA complement to the FA Ltd's is the (compact) FA 20-35/4 lens, in addition to the Samyang/Rokinon 14/2.8 for the widest angle. They are both very sharp, especially the Samyang if well calibrated. I used to have a DA 12-24/4, but I definitely prefer this combo.
Cheers

[Nicolas06]

Thanks to everyone for their replies! I have been clicking through test data plots and looking at image samples. Seems like every good lens can sing a fine tune when used in the right hands. I have seen some exquisite samples from the DA 21 and the DA 18-135 is no slouch either. Maybe the difference is measurable but noticeable only in certain situations.

@mtux - Your images of the waterfall from both lenses looked very nice!

I am fortunate to have the three FA Ltds and the FA 50 f/1.4. My hidden thought was that the DA 21 could compliment them and out-do the DA 18-135mm as a WA lens. Now I'm thinking that I might be better served by the DA 15. The DA 12-24 zoom sounds appealing but it's expensive and only works on APS. The Sigma 12-24 cheaper and FF but the images samples make me feel bipolar. But, all of that is for another thread!

For me, this really depend of your usage. If you have the 3FA ltd, to me if you go outside with all for APSC, you have no wide angle at all.

You can think why not the DA15 then? I agree... but the DA15 is an UWA, it is really extreme in the distortion it produce and its framing is for extreme cases. Having nothing between 15 & 31 when you just take primes can be anoying. For me if I don't plan for tight architecture shoots or cars, it is far more comfortable to just get the DA21. The framing - to me - if much more usefull. Well it will depend of what kind of shoot you like obviously!

The DA21 is also smaller and sharper than the DA15. DA15 has field curvature and can be soft on corners no matter what apperture you apply. DA15 you buy it for size, you buy it for exceptionnal flare resistance and exceptionnal contrast/micro contrast. And for the perpective distorsion it provide.

Here are a few example with both DA15 & DA21 to show you their strengths and usage is still different:

Here a few DA15. Look how the perspective are distorted and look. Even the shoot with the city you can see the small building look distorted. If you want clic at the 100% crop. The sharpness is good in the center but not exceptionnal... And the borders are not that great. Still it make quite impressive and interresting image.












And here a few DA21 shoots. Look how the perspective distorision is far less present. Look how the sharpness is more even... The focal length allow to shoot almost anything... Even if I think 24mm would be even better for that on APSC!