John Kelly , Apr 12, 2007; 09:00 a.m.
Browse P.N on this as there have been comparisons.
Having done a tremendous amount of slide duplication onto film, including several duplication films and pre-flashed Kodachrome 25, using the ultimate optics and systems (Sickles duplication camera with S-Planar), a good duplicate *to film* can be indistinguishable from the original, and can often be an "improvement," with no perceptible loss of detail.
However the D70 chip doesn't resolve as highly as film, and it's unlikely that your optic will be ideal. A copy stand, light box, and an old Micro Nikkor prime lens would probably perform better than any duplication attachment.
Scanning with a Nikon scanner, which would also remove dust in most chromes (issues around Kodachrome) will IMO resolve even better than that Sickles/Planar setup. I do a lot of it and am astounded.
The advantage to duplicating is speed, although you'll need to take slide dusting time into consideration. Actual scan time on my lesser Nikon V is 1.5 minutes with Ice...Ice takes about 20 seconds of that.