Originally posted by PJ1 The K-01 could handle the FF image circle so any FA or earlier lens could be used if they were inclined to continue down that path.
yes, however the whole concept of mirrorless was to make cameras compact the K01 was an experiment, nothing more. the K01 has enough space for a reflex mirror behind the lens mount however pentax chose to omit that, remove the entire pentaprism OVF system as well and make it a mirrorless camera.
i'm talking about real mirrorless cameras like the Leica M series with their 27.80mm flange which makes them much more compact than SLRs. The K01 had the same flange as an SLR, 45.46mm which for a mirrorless camera is
completely unnecessary and defeats the purpose of making a mirrorless camera in the first place.