Its 2008! .....forget the camera attachment for 35 mm slides.
By chance, needing a new scanner in a hurry, I bought an Epson Perfection V100
Not only is it excellent for conventional docs and photos, it has a framework for holding 4x35mm slides or 6 negatives in strips.
The software and the light in the lid control the action and the results are excellent.
This is a feature and price not available only a few years ago.
Other manufacturers offer similar scanners, but the expensive dedicated negative scanner which once was the only way to do a good job is now in my opinion a Dodo for extremists!