I have used the Epson 1640 SU Photo under Mac OSX 10.2 with USB and Twain 5 for scanning 6x6 slides, and had no such problems. It worked great, at least for web publishing.
I do remember I had some problems the first time convincing the scanner to skip the all automatic scanning. I've returned the scanner now so I can't help you by recalling what I did, but I think I had to click on the scanner window while the Twain was loading, or something like that... DagT > Fra: gfen <[EMAIL PROTECTED]> > Dato: 2003/07/10 Thu PM 03:18:23 CEST > Til: <[EMAIL PROTECTED]> > Emne: Re: scanner for 645 film > > On Thu, 10 Jul 2003, Gasha wrote: <---> > Since I've started to try out a macintosh and OS 10, I no longer could use > my Astra. I bought a refurbed Epson 2450. Faster, even on USB (no firewire > cable, yet). No newton rings, as it comes with a glassless carrier, and it > works under OS10. > > Now, I do have a question for others about this: Anyone using a 2450 on a > Mac, OS10 and Epson TWAIN5 to scan 645 negs? Using the supplied 120 > adapter, it seems to cut off the top and/or bottom edge and give me weird > little panoramics.. Am I the only person with a problem like this, and > what am I missing? > >

