I also tried an Epson photo xyz flatbed with transparency adapter once and found the following:
- pushed to the highest dpi, it was slooooooow
- color was not the best
- even at the highest dpi setting, resolution was worse than what I get with my D80 combo.
With my combo I can do around 3 slides a minute including cleansing with cloth + a blower (which is
critical). Dust and other debris leaves worse marks on your slides than any dust in your DSLR!
And the worst thing of all are transparency frames with glass - I needed to take all my slides out of these frames because the glass had some residue on it. Ugly!
The best thing with my combo: I now own one of the best macro-lenses and can have more fun with it than just digitizing slides. But it (digitizing slides) may come in handy as a good excuse to buy a macro

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Thomas (beware: Nikon-fanboy and moderator!)
My Lens Reviews,
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My Photography BlogD800+assorted lenses