Originally posted by KX5 You are talking about rangefinder system like Leica camera. But not compatible with actual Pentax Lenses which use SLR system.
I keep in mind my wonderful Canon AE-1 program which has a HUGE viewfinder with a complete and clear manual focus system. Canon AE-1 have split screen viewfinders which cut the image in half and you have to line the cut image up in order to focus. It is very accurate and fast. Technically it's possible to adopt it on a digital camera.
No, I was talking about SLRs... the Nikon FM2 in particular. The reason those had a great viewfinder compared to what we use today is a) full frame and b) the mirror reflects 100% of the light, unlike newer AF SLRs and DSLRs where something like 1/3 of the light is being sent to the AF sensor. If you have a mirror (Ricoh has the patents?) where you can switch between 100%, 66%, 50%, ... you can a) have a great, bright MF viewfinder and b) have an AF system that works in really low light situations... if necessary all the light is simply redirected to the PDAF system. Cameras with PDAF sensors on the sensor can't compete with that, because they need to squeeze much smaller PDAF sensors next to the image sensors. They aren't as sensitive.
I truly hope this is what Pentax will add to their DSLRs, both APS-C and FF. That plus better video functionality and I'm sold, mirrorless be damned.