Originally posted by monochrome I think it is fairly clear that Pentax is committed to K-mount. It is also clear that Pentax is committed to Q and 645. That means Pentax will need to create a fourth mount and complete lens line-up to offer a short-register mirrorless camera, or make a mirrorless camera body, adapters and NO LENSES at all, or buy Olympus (which would just bring them the m43 problem and solve little). I think the NO LENSES idea is highly unlikely (though Ricoh could brand something that way).
The sooner the Sony advocates on this Forum accept that fact and move on, the happier they and we will be. There's nothing wrong with using a Sony A7 and a K adapter. Nothing!! Go ahead - do it!!
I suspect there will be K-mount bodies, lenses and users for quite some time to come before Pentax is actually doomed.
Agree with a fourth mount make sense but where it make least sense to me is FF because K-mount was designed for it. The difficulty to design good wide angle almost disappear (except for some extreme UWA) and you can get smaller tele. The FA 43 & FA77 would be bigger with shorter registration distance at is would be for DFA100... But also a 70-200 would be bigger too. And of course you can keep K-mount and put an EVF on it or remove the mirror. Even through I think as of today you need to have an OVF model in your product line.
Then it leave us with some smaller sensor maybe bigger than Q because you loose too much shallow deph of field control and arre too much limited in high iso performance. From price, shallow deph of field and high isos, APSC look like a sweet spot and it would really make sense. Still the tele past 60-80mm start to be quite big. That would the challenge.
My conclusion is it make more sense to create an APSC or m4/3 or something arround that to be mirorless. To not be too agressive on the registration distance as a good compromise between WA and tele and to have of course and adapter to K-mount that preserve AF and all. Ideally the mount would be made with K-mount is mide so same diameter, support for screw drive and same connectors so you can easily addapt K-mount lenses on it just with a basic adapter.
This would give us with Q in Q mount, APSC with K-mount and the new short registration distance mount, FF in K-mount and MF with 645 mount.
In the long run, you could sell the APSC K-mount to be compatible with the FF mount, for OVF instead of EVF and for capacity to handle any long lense without issue... Not forgetting fast AF.
APSC short registration mount could be sold as small body for trips etc, good for being unobtrusive and still high quality with EVF etc.
The FF will be K-mount, will be OVF only the first years for sure and it would be the ultimate swiss knife camera, good high iso performance, lot of deph of field, lot of sharpness, good colors... supporting all kind of lenses and for the more serious work. It would have at least 36MP to support the APSC K-mount lenses in 15MP.