I dont know what field camera it is, but my buddy had one where he had to unscrew the rear element to mount lens board on the camera, pop off the ground glass and screw it on from the backside. This is always an option and just something to think about......hope this help some what. PS I have a toyo 45AII and a Schneider Super Angulon 90mm f/5.6 (not the xl) and it has plenty room to fit the lens.