[obican]

Most recent (designed in this century) medium format camera systems mostly have the same size digital sensor as their negative backs. That's because they are designed to be 6x45 systems though, no real 6x6 or larger systems going on here. And even then, it took most of those companies at least a decade to get a true 6x45 sensor.

 

Checking the sensor size and seeing they are merely 54x40mm can be deceiving btw, as 6x45 film actually measures something like 56x42mm or so. Focus breathing or viewfinder coverage has more of an effect on the image size so that 2mm difference is mostly irrelevant.