You mention a tiny dim ground glass, which I assume is your viewfinder. Does your camera not have Live View? For me that helps immensely with composition, focusing, and checking depth of field. It's like having a very bright ground glass and it can be magnified similar to using a 5x or 10x loupe. At 3"x3" it's no 8x10 but it isn't all that much smaller than 4x5.