Doc: I've been asked this many times, so I'm copying a post I made from "Fans of Large Format Still Photography" which I started on Facebook. Here you go!
"I've been asked by various people about my method of digitizing negatives. Here is a snapshot of my system. Ultra simple. A lightbox with daylight balanced bulbs , a negative carrier from a scanner . . . I have one for each format, shown is the 4x5. And I copy with a DSLR (in this case a Pentax Ks-1, but I also use my Canon Rebel) and a Tamron 90mm f2.8 Macro (I have four of them, so don't ask which one - they're all great!!). That's it. I photograph the negative and reverse it in GIMP, and process the resultant positive the way I would any file. Now you know. This can be duplicated for a few bucks with a lightbulb and a piece of frosted glass."
It's true that this is a digitization, and it is unfortunate that even the best screens only resolve about 3000 dpi (or 3 megapixels) maximum, so you get the comments "What's the big deal? My cellphone pictures are just as good." Yes, on a screen, especially if you are viewing your pictures on a cellphone. But do an enlargement and all comparisons stop. Yes, your cellphone pictures will look just as good as that of my Pentax K3 which is 24mp. This is also why I don't scan . . . this is easier, and looks just as good on a screen.
Now consider that a 4x5 negative renders about 900 mp, and a 5x7 does about 1500, view a darkroom print of say 16x20 from one of these formats and a cellphone print of the same size, and you're looking at a visual joke. Even medium format cannot render such detail. Most museums are filled with large format archival shots. That's why they look so good. Ansel Adams and all that.
But it's the lot that we large format photographers have to deal with. Even then, some of the information is contained, like the dazzling tonality and the smooth tonal gradation.