I have the same scanner. Would you mind sharing your setup? I've only used mine for flat-bed document scanning, but do have a bunch of old family slides.
I have the v750 and scan medium and large format film with excellent results. You can buy Viewscan software from https://www.hamrick.com, made by a NASA JPL engineer, if I remember correctly.
You get a perpetual license (I reinstalled after 12 years and the updated software ran on my old license code). The software can pull detail out of even the worst negative. I cannot recommend this highly enough! I do have SilverFast as well, and have tried the Mac-native scanning, but Viewscan is the best.
If you have slides and you haven't kept the original film adapters, you can find them on ebay or even Amazon. They are simple plastic holders, nothing special.
You can usually select a particular film type if you scan color negatives that will automatically color correct for the film quirks. All in all, a very easy process once you get set up.
Hope this helps!
I bought this thing when we moved, to get set up ASAP for a remote home office, so documents and some photos have always been the purpose. I had taken the slides in a box to a photo place, where they used some setup with a DSLR to get JPEGs, but now I'll need to dig the box back out. Thanks!