Originally posted by zapp Tamron has a nice f/1.8 line of primes that can be considered small.
Smallish ... 67mm filter sizes, I think. Good basic lineup - 35mm, 45mm and 85mm, and I think Winder believes the Sony FE 55mm f1.8 is actually another Tamron SP.
If Ricoh's instructions to Pentax are, weather this global camera market decline by operating on a tiny budget, work on only a couple of lens releases a year until things get better, I would have thought they could do worse than rebrand all of them from Tamron and say, do their own 24mm. You could get a modern four prime lineup out at the same time, similar to what was done with the D FA zooms.
But it looks like they've gone for big, corrected and f1.4, along with the necessary development time (Sigma have said it takes about three years to design then release a product), and if you want smaller, that's what the older Limiteds are for.