Though I really do not know, I would suspect that Horseman will not offer a 5X7 version of their 617 camera. They have never done the same with their 612 camera in 4X5. The 612 and 617 cameras are for very specialized usage. Also in the case of the 612 format, Horseman offers a 6X12 Back for 4X5. Canham Camera offers a 617 back for 5X7 cameras by the way.