Originally posted by yipchunyu I know that K-01 has the same flange focal distance (k-mount). However, since it doesn't has the mirror inside the camera. Can pentax make use of the space and make the future lens much smaller (as if part of the lens tube sit inside the camera)?
I doubt this can be done. There is just too little space inside the camera.
Maybe only with very simple and slow lenses using small elements and minimal mechanics (no zoom / collapsing mechanism helixes). If i look at the back of my lenses, many of them, not even fast ones, use up quite a lot of the area mount offers. They could be shaved down a little, but i don't think as much as would be required to fit them in the sensor sized box.
But hey. If they can stick a reasonably bright (f/2) 16, or 24 mm "pancake" down that hole, i might change my thoughts about the K-01.
And
at f/2, without counting in any element housing tubes, guard spacing or any other technical details,
knowing the K-01's APS-C (23.7 x 15.7 mm) sensor size, you could
fit a 15.7*2=31.4 [mm] or wider lens in there.
BTW, the diameter of Panasonic's 20/1.7 lens optical elements is roughly 21mm and that is for a non-retrofocus lens.