difference between Mamiya RB67 and Mamiya RB67 Pro SD

Hi,

is there much difference between the Mamiya RB 67 and the Mamiya RB 67 Pro SD as i'm about to hire one of them and the older one is cheaper to hire....I won't be using a digital back either only analogue, so that may be the only difference.......

thanks for your time..

ade...

The only two big differences between the RB Pro, and the Pro-S & Pro-SD is the double exposure prevention system, and the SD had a larger lensmount in order to use the fisheye and tilt shift lens.