If you're doing a lot of slides, or need high quality scans, you'ld be a lot better off with a dedicated slide scanner. They are built to do the higher magnification you need, and you can easily insert and remove the slides (and they are aligned better). Of course like all good things this comes at a price, and slide scanners are not as cheap as flatbed. But depending on how much you have to do, it may be worth it.
WebDude😎