After perusing the archives I came accross some concerns regarding film sag. The posts struck home as I am shooting 810 straight down. I have been satisfied w/ results so far, However I am considering buildig some sort of vacuum holder that will insure that these images really are as sharp as they possibly can be. If I have a # of small holes around the middle area with hose & tupperware attached to a sac rificed film holder, could that cause a reverse problem? Ideas? Comments? Ajectives? Other than a dust problem, is there any reason not to try laying my film on a sheetof glass, of course, adjusting focus to the different film plane.