Originally posted by motorhead9999 if you're looking for fast primes (again, new), it's a frustrating thing, especially when a brand announces a new lens that you have an interest in, only to find that you can't (and probably never will) get it.
So yeah, it's a mixed bag situation right now. Yes, there are lens limitations, but for the majority of what IS covered, it's done well.
+1 @motorhead9999 and just to add, Pentax probably exists today because they offer something that is different than the competition. IBIS, pixel shift, astro tracer, as well as a lens line up that is unique.
For example:
Canikon: DFA 50mm f/1.4 (which Pentax will probably be released in 2018); Pentax: the pseudo-pancake 43mm f/1.9 Limited.
Canikon: 85mm f/1.8; Pentax: again smaller 77mm f/1.8 Limited.
To me the weakest link is a modern FF 20mm f/1.8 prime, but your 15-30mm f/2.8 zoom covers that. And because of IBIS (and the wide focal length), the need for speed is less of an issue, unless your goal is uber bokeh which is rarely a wide angle possibility unless your foreground subject is at minimum distance.