I did an A : B comparison of a neg duped with a D700 with a Nikon bellows and a 50/2.8 Micro Nikkor (@ f-8.0) with the Nikon slide copying attachment shooting on a tripod into a north facing window into a blank sky with and without a piece of waxed paper over the window. With the Micro Nikkor and the Bellows a 1:1 dupe (no crop) was possible. This compared to a scan done with my CoolScan V.
No matter what, I could not get the quality from the slide copier that I got with the scanner.
Anyone want to buy a really clean Nikon bellows and slide duplicating rig?