I recently bought a Epson 850 Flat bed scanner for scanning 4x5 negs. I initially tried Vuescan and Silverfast software (both of which I use on my Plustek 120 scanner for 120 film). But for some reason the scans were horrible especially trying to get the scanner to make the correct crop. I was frustrated and pulling my hair out trying every setting in the book. I then noticed that the scanner came with its own Epson software. As soon as I tried that, "Bobs your uncle" I started getting fantastic scans (very large scans at that) Now I use that software all the time and at a resolution of 1xxx something which gives me a 20 to 40 MB scan.
Later

Neil