Find someone/somewhere with a 8x10 scanner.
The only photographer I know who scans his 6x17, sends his film upto Singapore for a high-res drum scan.
Or find the meanest flatbed scanner and scan them like a document. That's how I use to scan my 4x5s and 8x10s.
...or like the others said, two scans and a stich.
Stu
