I have a 6x9 Graphic roll film back that I use with my Crown Graphic Special. I have only used it a few times outdoors but so far I haven't noticed any light leaks (I'll have to watch out for them now). I have 6x9 marks on the ground glass for focusing and composing and everything has worked well so far. It's a great way to try a different format without committing to different bodies,lenses etc. It is a bit of a struggle changing from GG to rollfilm back then back again but for a few shots at a time I don't mind and I do it with Grafmatics as well.