Originally posted by kadajawi The 645Z couldn't be 4K. It is a very bad sensor for video. There's no way they could read those 50 MP 30 times a second, and that's what you need for good video. They just skipped a ton of pixels to get it to do 1080p, resulting in bad quality.
How many still camera with a large sensor do a full sensor read on video? Even the best like GH4 and Sony A7s or A7rII don't really do a full sensor read, they do a full read on a crop...
So A7s/A7rII get more like real APSC sensor for video and GH4 get equivalent of full read on a 1" sensor...
The MF sensor are not designed for video. Reality is the circuitery and processing power to do that would be enormous and affect the still image picture quality. (less part of the sensor surface dedicated for photon gathering, heavy need for cooling down the sensor, more expensive design with lower yield rates). Even the most advanced sensor from A7R-Ii don't do it there too many photosites to do that. So either you are a manufacturer, make a business plan and ask for Sony to make you a low pixel count MF sensor like a 8MP MF one and dedicate it mostly for video and try to sell it as such to videographers... or you ask Sony for a 51, 80 or 100MP MF sensor, and try to sell it as such to photographers.
I know thar you guys video gear heard think that everything should be made first and foremost for video because of course it does cost nothing, because your client ask for it and you'll never buy a camera that doesn't do video better than any dedicated video camera, because you use it all the time and everybody and their mother need 4K (hey why not 8K ?) video on their MF camera with a clean HDMI out for the dedicated recorder plugged to it.
But this is not how things work for the moment.