On the assumption that Pentax do provide an adapter for its existing DSLR lenses I wonder what the pros and cons would be? On the face of it the Sigma 85mm F1.4 EX DG HSM, with it's excellent centre resolution at f/1.4 (review
), would offer the equivalent of very nearly a 500mm telephoto. You'd probably need to operate at f/2.8 or brighter to avoid excessive diffraction softening, assuming the centre of the image from that lens is effectively diffraction limited in its resolving power. And any adapter would need to be designed very much with removing stray light that regular DSLR lenses would be providing outside the relatively tiny sensor.
Maybe I'm getting a bit carried away here as the Sigma 85mm F1.4 EX DG HSM isn't cheap and I'm sure the bulk of the target market won't be in the least interested in that body/lens combination but for those prepared to think out of the box the Pentax Q may offer some unique options at prices APS-C cameras couldn't approach. But, as always, so much depends on the reviews. I wonder if Pentax/Hoya would break with tradition and get a review sample over to Gordon, assuming he has the time to do a review in the first place?