The major camera manufactures and the film industry should consider re-inventing the half frame camera to accept the modern Digital autofocus lenses by Nikon and or Canon. I would think if one just took a Nikon f-6 and made a smaller film gate openning, shortened the advance distance and turned the lense mount by 90' one could have a winning combo without worring about packing two sets of lenses. It should get around 70 shots or so in half frame. I for one, would buy one in a flash for a backup film camera to my digital stuff. Don't get me wrong, I love digital equipment...I have two d-200's and a d-80. I still shoot medium format film and 4x5 (55pn and 6x12) on occcasion.
Regards from sunny Guam, USA.