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The analog version HV90x shows the entire 6x4.5 cm image.
The digital version HVD90x limits the field of view to a smaller area of 36x48 mm, corresponding to what the sensor sees. But that smaller part is magnified a bit more (3x vs 2.7x).
The HVM viewfinder works great as long as you do not turn the camera on its side to shoot in 'portrait' orientation.
When you do that, you are not only looking at the screen from the side, but the image is upside down and reversed too. Very difficult.
Hasselblad's reasoning was that the sensor offers enough MP that instead of turning the camera on its side, you just crop a 'portrait' orientation image from the larger 'landscape' orientation image, and still end up having an image that's good enough.
But when you do a lot of shooting in 'portrait' orientation, there's no way round the 90 degree prism finder.