The maximum dimensions of the case are 21.25 x 10.75 x 21.5 inches, which would be approximately 54 x 27 x 54 cm, and there is a foam block in the cover that could be removed covering about half the depth that's about 5 cm thick, so it wouldn't fit the 12x20, but might work for Dave's 14x17.

My camera is 18" square including knobs and not too thick, which is pretty compact as 11x14" cameras with reversible backs go.