Originally posted by rptdc Considering adding a wide angle prime. 1. Never purchasing a prime wide angle before, should I expect some image distortion with the 15mm? 2. Also, any general opinion on the above 15mm vs 21mm?
Back in 2013, when I was looking into which Pentax wideangle prime to get, I had the DA21 on my personal shortlist, too. But then, from as far back as the film days, I had been drawn to that 24mm-ish-FF-equivalency FOV. 28mm on film had always appeared to me as okay, but not really wide enough, yet I didn't want to go completely overboard with perspective distortion and volume deformation, which is why I picked up a Sigma Super-Wide II 24mm F2.8 for my Minolta X-700 and fell in love with it. Later, on my Sigma SA-9, I shot a 24-70mm zoom, which offered the same FOV at the wide end.
In Pentaxland, the closest to what the Sigma Super-Wide had given me was the DA15, except that it did the job even better. Perhaps more field curvature, but definitely better microcontrast, those beautiful Pentax colours, remarkable flare resistance (where the Sigma, well, kinda sucked), Limited build quality, almost negligible barrel distortion (where the Sigma exhibited the somewhat ugly mustachio type), and those beautiful starbursts (smc-DA version).
Ultimately, only you can decide if you're gravitating more towards a pronounced or a moderate wideangle, which the DA21 would give you. If you got the DA15 first, you would leave the door open to get something like the DA21 later, unless you opt for the arguably even more attractive HD DA20-40.
Despite its fairly slow widest aperture of F4, at least in my photography, the DA15 has proven a wonderfully versatile performer, regardless of whether I threw architecture, interiors, landscapes, or even family-journalism subjects at it. It's one of those lenses that can pull you into the Pentax APS-C system. The attached images should give you some idea of what this lens can do: