its fun to discuss and dream about lenses isnt it
I have been thinking about primes a lot and since the current lineup has some pretty close focal lengths, I think its a waste to get them all, but which ones are the best choices.
Some random thoughts:
DA 14 / no competition, but expensive and if there is ever a > APS-C pentax you wont be able to use it
DA21 vs FA20 / not really a difficult choice since u dont have much of a choice given that the 20 is too hard to find. I think its a tough call, the DA has the build quality but the FA is usable on FF as well altho it carries a very hefty pricetag.
FA 28 / FA 31 / FA 35 : I havent tried the 28 but I hear its good and I have the 35 which is fantastic and to me a lot better than the FA 50. Of course who doesnt want the FA 31 but its so overpriced that it would be a lot better choice to get both the 28 and 35 instead.
DA 40 / FA 43 / FA 50: Ah, the DA40, sorry I dont see the point, its too small! Doesnt look comfortable to use at all, and its not fast eanough and the screw type cover is a pain. The FA 43 is reasonable and has been tested as one of the very sharpest pentax lenses when stopped down AND its also small, but not too small, a very nice size. The FA 50 is fast and cheap but I havent been too impressed with mine, its sharp but the FA 35 has got so much more "pop". I think the slightly wider FA 43 should be the best choice of the three. Possibly adding the 50 later for completion.
DA 70/FA 77: Heres one I dont understand, according to formal tests the DA should be as good or better than the 77 (ref photozone) and the price is certainly very nice but come on man... look at the pictures. I think the pics I Have seen with the 70 have mostly been dull and lacking pop, and I keep seeing great shots from the 77, I have no doubt the 77 is in a different league than the 70. So unless youre on a budget, the 77 wins.
(FA 85: droool....this lens kicks so much ass...but I will never afford nor be willing to pay so much for one)
(FA 135: bring it back! give me a DA 135 f2.0 SDM).
So I end up with: DA 14, DA 21, FA 28, FA 35, FA 43, FA 50, FA 77 (and a 100 macro) Altho Id take an FA 20 if I could, I mean who wants a prime thats slower than a zoom, then whats the point.