samsen wrote in post #15101850
Yes. They could have same problem with focusing as we do even now and that might be a right angle / magnifier. I know Canon, Nikon and Olympus have some nice opticals for this purpose.
My other guess is actually this is a medium format camera 4x4 or likewise that has no TTL viewfinder. Diameter of lens makes me to think more strongly for a medium format such as Hasselblad rather than 35mm.
Waist level finder in place of a pentaprism is a possibility
Canon had only rangefinder cameras in 1958. Same for Nikon, as the Nikon F did not yet exist. Same can be said for Olympus, whose first non-rangefinder did not come until the Pen F.
Both Exacta and Asahi (Pentax) had 135 format SLRs with waist level finders in that timeframe. Exacta offered a 6x6 SLR then, as well.