jingq
you can use any Hasselblad Viewfinder adapter compatible Screen.
We have now done a version for a customer who took off the Arcbody Accumate screen he had on there and uses it now for his Leaf Aptus II 12R on the HCam-B1.
Combined with the 4x Loupe finder that makes very easy and bright focusing,
it´s exactly as smooth as on the arcbody (of course) and as we do not have any Prism or mirror to pass by it´s probably the brightest finder you can get on that kind of camera.
Also remember while the Rodenstock or Schneider 24/23mm wideangles are f5,6, the Canon 17 and 24mm lenses are f4 and f3,5
which is 1 f stop or 1,5x brighter and you can see this very easily.
And because of the retrofocus (longer flange focal range- thus less light falloff!) the corners are bright enough also. No centerfilter needed- no colorshifts, no moireeshot
no colorfringing !
Greetings from Munich
Stefan Steib-Hartblei.de