I've read a few books stating that glassless negative holders, especially for 4x5 and larger leave the negative quite wavy. I checked my negs, tight in my Omega D2V holder and sure enough, while the holder is fine, the neg is all over the place. Checking the glossy side reflections of straight lines confirmed the neg was anything was flat. I know the counter-arguments about depth of focus and 4 more surfaces to keep clean. I purchased a glass carrier for my 4x5 and have two questions; 1. Any suggections on using glass carriers concerning preventing newton rings? 2. Can I use the open 4x5 carrier for roll film negs or will the excess light spill-over fog the paper? Will I need to mask for smaller negs?