The Gilde 66-17 MST will shoot all the formats from 6x6 to 6x17. It has an internal mask and so you can switch formats in mid-roll. Naturally, view cameras can shoot many format by changing the back--Sinar made a back that goes from 6x4.5 to 6x12. The new Fuji rangefinders will do both 6x6 and 6x7. Holga will do 6x4.5 and 6x6.