Originally posted by zapp 2/24 would make for a better angle of view - closer to 35 mm in FF land.
I am about to give up waiting for Pentax lenses and TCs. A couple features make me stick to Pentax, but I am about to leave. The best lenses in Pentax land are only availbale used and I can not identifiy any clear planning for updates. We are offered old FF designs along with APS-C designs and no line up is complete at all.
Since you talk about TC, I'm guessing your concern is lack of options at our Tele end? Pentax DA lineup is almost complete, actually on the shorter end I believe it is more complete than any other mount (barring our lack of Tokina 11-16 equivalent). DA15, DA21, and DA 70 have no size / FL equivalents in any other mount except mirrorless.
I think Pentax users have the illusion that Pentax have to perform and compete with Canonikon. If we look at the innovative lens designs Pentax is coming up with, certainly this is not what they are trying to do. If this is what you'd like to get it is indeed better to switch. Each second spent waiting could be spent shooting!
An APS-C optimized DA 28 would raise the bar even higher. If it could be faster than 2.8 and be a true limited in size, I will have no complaints
For people wanting a DA 24, why cant you just crop the DA 21? Imho it's close enough.