I used the Project and Shoot method myself. My grandfather shot slide film from 1953 till 1989, and had 54 pre-loaded carrosels that I wanted to convert to digital files. I picked up the carrosels (no easy task - 54 slide carrosels filled up the entire back seat and cargo bed of my SUV), and set about shooting them.
I projected the slides on a piece of posterboard, using the dull side, not the shiny side, because the shiny side would make a hot spot (a glare from the projector lamp) in the middle of the image.
I set up my digital camera on a tripod directly behind the projector and just slightly above - the less difference in angle between the projector and the camera, the less distortion of the rectangular image. This is what my setup looked like (click either pic for the full-size version):
I zoomed the camera in tight on the first slide and focused. Then I put the camera in Manual Focus mode - this prevented the camera from automatically refocusing for each shot, which A) saved battery life, and B) insured that every shot would be in focus, even those that were too dark for the auto-focus sensors to lock on.
I set the camera on Program AE mode, allowing it to meter and set its own aperture and shutter speed, and I used 400ISO. Most importantly, I set the white balance for Tungsten, because the projector lamp is a very yellow-tinged incandescent bulb that would cause a yellow hase over each shot; setting the WB for Tungsten compensates for the yellow tinge and makes each pic more true color.
Once set up, I used the remote advance for the projector, and the remote shutter release for my camera, advancing through the slides and allowing the projector to autfocus before I took each shot. I found that it took me about 13 minutes to shoot a carrosel of 140 slides; some took a bit longer, because I had to turn all the vertical slides horizontal to make them fit the frame of the digital camera. I tried not to look at any of them as they scanned, which would only delay the process; I just looked at them later on the computer.
For post-processing, all I did was run Noise Ninja on them to cut down on noise and add some sharpening. I don't have any dust removal software.
The quality is not nearly as good as a scan, but the slides are clear and viewable, and will no longer degrade.
Here are some samples. The first is is one of the oldest, from 1953, and the second is one of the more recent, from 1987. Click on either to bring up the full-size file.
It took me a month to scan them all; thankfully, my grandfather spent the money to store all of his slides in carrosels instead of in boxes, and he also kept the carrosels in their original cardboard storage boxes, which reduced the amount of dust on the slides. When all was said and done, I had 7,051 slides converted to digital files, which I burned onto DVDs and sent to all of my grandfathers children and his adult grandchildren. They were impressed.
Those were just so horrible.
