Today, the Nikon ED5000 is the best slide scanner available at a mid range price point. Nikon toll free 800 help is also pretty good. It's the only scanner available with a slide feeder that common folk can afford. The ED5000 slide feeder would be needed if you have something like 1000 slides, and it works better than the first generation Nikon feeders. Nevertheless, if your cardboard mount slides are "dog eared," it may not work.
Digital ICE^4 is essential for all but the least discerning aficionado. It removes scratches, watermarks, coloration (from fading or improper processing), and dust from slides. It's amazing how noticeable that stuff becomes in a scan, when it doesn't even show in a slide projector.
A number of scanners offer Digital ICE^4. Canon offers its own brand of slide repair software - FARE - but I suspect you'd get ø (zero) help from them if questions arise.
You may be able to obtain an out-of-print Nikon book on scanning (for FREE from Nikon), or possibly a third-party book on scanning. Scanning is actually quite complicated for discerning photographers, and most instructions don't explain completely what all the software settings actually do. Sometimes you just have to try different settings.
A high resolution slide film like Ektachrome 100 or Fujifilm Astia 100 has a resolution of about 4000 pixels per inch. That should be adequate sharpness for a "straight" digitally-processed inkjet print 8x10 size. You'll need to use Digital ICE^4 and PhotoShop and possibly other software to tune things for your most important shots. It's better to depend on "upstream" functions the most. In decreasing order of importance:
- Take a good shot to begin with.
- Process it and store correctly.
- Scan it correctly.
- Manipulate in PhotoShop.
- Print it well.
Another way of saying what I just said is: don't depend on PhotoShop to bail you out when things get really messed up.
Note that Digital ICE^4 doesn't work entirely with Kodachrome film - it doesn't remove scratches in Kodachrome slides. Some people
claim that VueScan software does sometimes work on Kodachrome using Digital ICE^4.
I sort of assumed (maybe incorrectly, Bibo) that you're talking about color positive slides. A slide scanner with Digital ICE^4 will work for color negative films and B&W negatives also - to varying degrees. I recommend you embed the scanner profile into your (scanned) digital images using PhotoShop or, better yet, Bridge or Lightroom.