So I have the perfect walk-around lens (IMHO) in the DA*16-50mm f/2.8. Fast enough to use indoors, and when using it outdoors, set it at f8 and the colors, micro-contrast and overal "pop" of the images is basically as good as any good primes I have in its range. OF course it won't make me sell my DA 35 Limited or my K 50 f1.2, but overall I'm very pleased with it.
Yet sometimes I don't want to (or can't, really) take it due to size - on a bike ride for example, or when I'm going to walk around all day. For those days I thought I'd buy a DA 21mm SMC (around 200 dollars, hopefully I find it for less - the HD is out of my budget I think. I bought my 35 Limited for 179 shipped and the 70 Limited for 174 shipped, which is the reason I was able to get these fine lenses in the first place).
But the thing is, I'm not overly excited about the images from the SMC 21. The HD version, I think has subtle but noticeable improvements in contrast and micro-contrast in particular, and balancing of colors in general, which make the images as a whole more appealing. I should probably mention that I had the DA 21 before, for a couple of weeks. I got it on a trade back in my K20D days and when the other person suggested after a few days that we should revert the trade because they were not overly excited with the DA 16-45mm f4 either, I jumped on it because I was less excited with the 21 (my first Limited!!) that I thought I would be. And I also missed having a general walk-around zoom and the 16-45 was perfect for that (if the "wobble" of the internal lens barrel hadn't gotten worse I wouldn't even have bought the 16-50, I'd be happily shooting the 16-45 still).
So to make a long story short, I'm seeing a nicer look to the images in the HD DA 18-50mm f4-5.6, than I see in the SMC 21mm. I've been looking over the internet everywhere for pictures of both lenses and while the 21mm is probably much better than my initial experience would suggest, it's not on the same level as the HD 21mm or the HD 18-50mm. (the SMC 18-50mm, on the other hand, seems to be a bit disappointing in terms of micro-contrast, colors and sharpness - on the same level as the 18-55mm old kit lens).
Now I know the HD 18-50mm is probably going to require being more careful with it, as the build quality is a bit disappointing, but what I'm after is the look of the images, and a very small carry-around lens (134g for the 21mm, 158g for the HD 18-50, not much difference, and both are small when the 18-50 is retracted). Oh and the HD 18-50mm is WR.
With either one, I'd carry the SMC DA 70mm on a pocket somewhere, in case I need something longer.
Go ahead and tell me I'm crazy for considering this cheaply made lens instead of a Limited for my intended purpose.... (something small and light to carry on the K-S1 when I don't want to carry the K-3+DA*16-50mm).
Flickr search on the HD 18-50mm...
Search: HD 18-50mm pentax | Flickr
Flickr search on the SMC 21mm...
Search: SMC 21mm limited pentax | Flickr
(I'm viewing the images on a 32" 4K monitor, and the best SMC 21mm images seem to be taken with a K10D... the ones with newer cameras don't seem to have the same "pop").
I've looked at review pictures, the 21mm Limited threads, and in explorecams as well.