Originally posted by Na Horuk I think Pentax should stick to K-mount, but keep developing XS lenses for mirrorless cameras.
And Pentax could easily turn 21mm and 70mm ltd into XS versions. Plus it could make lenses that protrude into the mirror box - which I think was the original intent with XS lenses. This saves space, while keeping total K-mount compatibility without the need of adapters.
+1
Wide angle lenses are the critical factor for mirrorless,
and keeping the K-mount offers two options.
The first option is with retrofocal (telecentric) lenses,
where the rays coming in from the long K-mount register distance
go straight in to the sensel wells at the edge of the sensor,
with little vignetting or color shift.
The downside of this is the increased size of the lens.
The other option is the XS philosophy,
with wide-angle lenses going deep in to the body of the camera.
The color shifts and vignetting need correction (in the camera or in post-processing),
but the whole package is very compact.
The example I like to quote is the Voigtlaender Heliar 12/5.6
(
Voigtlander SL 12/5.6 15/4.5).