Originally posted by Simen1 - Larger sensor: Doesnt need to be redesigned, Sony already did that.
- Larger shutter: Just use one of the shelf
- Larger mirror: Same
- Larger mirror box: 645N should be a good blueprint
- Larger pentaprism: Yes, just pick one from the 645N shelf
Redesigning the body isnt very expensive. They even redesign bodys for 500$ cameras quite often. Except from the sensor, none of the parts you mention are super expensive. Putting the parts together shouldn't be much more expensive then the 645D-645Z upgrade. Except from the sensor of course.
Yes, if the goal is to increase the portability, both the register distance and sensor size should shrink. But its not strictly necessary to loose the mirror. Pentax Auto 110 uses a mirror and have the same sensor size as mFT. They managed to make that quite small despite the mirror. Anyway, I don't think the market is really moving towards portability (= small sensors) in the long run. I think APS-C K mount with compact lenses are a good low end for system cameras. Q are probably at its end. Pentax have more to loose by starting a brand new lens line up, then to gain in terms of size and competitiveness in the small system camera market.
You remind me of the president of the scanner engineering company I once worked for. Everything was easy to him. But:
1. Semiconductor sensors are thicker and bigger than film: that pushes the shutter toward the lens, intruding into the space required for the focusing screen and mirror box
2. Even if there is an off-the-shelf 645-size focal plane shutter, it's almost certainly a different shape which likely changes the mirror box design (the old 645N shutter is obsolete with a 1/60 sec synch speed)
3. The 645N had only a 3-point AF system: if that's not good enough, the new camera needs a redesigned secondary mirror and mirror reflex mechanism.
4. Is the 645N's 6-segment light meter competitive: if not, then parts of the prism need redesigning
5. Is the 645N's viewfinder information display competitive: if not, then parts of the prism need redesigning
Maybe the outward shape of the 645FF might look like the 645N but almost everything inside it will need to be designed from the ground up. That's especially true if the 645FF needs to offer competitive features in AF, metering, and OVF information displays.