Originally posted by ismaelg
Granted, my scanner is a very old one but from what I've seen drum scanners are wet mounted forcing the image against the drum. From what I understand that helps with dust as well.
As you may know, the drum is extremely smooth (flat, in its true meaning). The image is taped down and some scanners small tangs lightly grip the rebate taut. The liquid is antistatic and repels dust, but also increases sharpness, in turn increasing detail and picking up in the dynamic range (among myriad other tricks). Drum scans have never been cheap (nor quick), but they are the only way to go if you insist on absolute quality for an outstanding image in the first instance e.g. framed prints for exhibition/sale: don't get drum scans of "also ran" photographs; just the very best you have, and scan and profile for large prints.
Epson scanners are all very good, but they are not a patch on Heidelberg
Tango or
Hell drum scans. The file sizes (profiled, full colourimetrics and export to lossless .png, .tif) can be huge and intimidating, but usually go through a 'trim' process internally. I have two, 1Tb Seagate storage units for my scans. It is important to invest in storage if you get hooked on the drum scan bandwagon! And also get used to eating baked beans, because it is a brutal blow to the finances...