Focus Having a problem with ground glass. Got a fine ground glass for my 4x5 press view. I replaced the old glass which was a coarser grain .But now my images seem ever so slightly soft as though I missed in focusing with my magnifier. Dug out an old micrometer and checked thicknesses. Its been so long since I worked with a micrometer and I probably have the wrong readings but there is a difference between the glass the old read about .013 and new glass .005. It is only a tiny difference if my measurements make no sense But would it be enough to throw my focus off a hair? I have a 150mm F/5.6 Topcor which gave me good results on my monorail,but I can't carry that into the field.