Is their any alternative to Scheiders "high end" vacuum backs? When pointing th e view camera downwards, the film will buckle in the middle causing focus proble ms as I have exceeded my Depth of Focus limits. I would guess there must me a w ay to slide a very hard but thin piece of glass into the film holder which would keep the film from buckling when the holder is parallel to the ground. Has any one experimented with any systems to prevent film buckling? I have considerd th e "high end back", but it requires special film holders and the vacumm part is t oo big and bulky to carry in the field. Thank you..