Originally posted by Digitalis In my comparison between the new DFA21 and existing 20mm lenses for Pentax* the M series lenses M20 f/4 and K24 f/2.8 can't compete, optically the DFA21 is quite a bit sharper than they are.
That's to be expected. Even my DFA 28-105, which is sometimes as little more than a kit lens, out resolves many M series and K series primes (although not by a huge amount). The main issue with the DFA 21 is the price and the fact that, if you confine it mainly to landscape uses, it really is kind of super-specialist lens. For several years I tried confining all my ultra-wide landscape work to the Rokinon 10mm and the DA 15, and in the end I had to buy the DA 12-24 --- I just needed the FOV versatility that a zoom brings. My advice for the OP would be to start with zoom lenses and then add primes for specialty purposes --- and even then, mainly for focal lengths one's comfortable with. You don't want to be swiping lenses with every shot.
Originally posted by turbo_bird I also recently got an F24-50 f4 zoom that I like.
This lens gets a lot of praise from photographers who use it, and without a doubt it produces very nice looking images. But it did not perform particularly well on resolution tests in magazines like Modern Photography and while that's not necessarily a huge issue (it's probably plenty sharp for most purposes) one should be aware of that going in. Furthermore, there's the issue of how well the lens fits with the other lenses in one's kit. For example, the 24-50 wouldn't mesh well with the DFA 28-105 for the simple reason that 24mm isn't that much wider than 28mm.
When it comes to using the k-1 as a landscape kit, it's hard to avoid the necessity of the DFA 15-30. I realizes it's big, it's heavy, and it's not filter friendly. But the flexibility of the zoom can be tremendously useful in the field. If you ever go to Horseshoe Bend, for example, 24mm is not wide enough to get that shot (you need at least 18mm). That's true of a number of iconic landscapes places across the nation.
The DFA 15-30 @15mm: