Defaults to vertical? Which camera did you get? Mamiya 645 slr is in landscape format normally.
It does? That'd be a nice surprise---the material I found online suggested that the first generation were vertical and they switched to horizontal around the time of the Pro. Detailed information seems kind of thin on the ground for these cameras, though.
San Diego, CA, USA
The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
-The Little Technical Library, _Developing, Printing, And Enlarging_