Sorry about the length of this response, but this is a topic that I've researched heavily, and one I've not only written about somewhat extensively, but one that I actually have a lot of experience in now.
I have thousands of slides and negatives that I'm slowly digitizing. I've already digitized a couple thousand of my slides. And I can tell you this: I don't know of a fast process because each slide needs to be inspected for dust, hairs, lint, etc. and cleaned if necessary, and depending upon your scanning method, this can be a quick or very slow process in itself. But the way I do it now is certainly one of the fastest -- and one of the best.
If you've a mind to, I recommend you read through an article I wrote on the subject at one of my blogs. It is targeted toward the neophyte so you might want to scan over portions of it that you're already familiar with. You can find it here:
Digitizing Slides to DVD: Which Way to Go? Michael Sez
I started out using my Epson 3170 scanner to duplicate my slides. But even when set to its maximum claimed optical resolution -- 3200 pixels per inch (ppi) -- it seemed I wasn't getting all the detail. More recently, I bought an Epson 4990. Still, even at its max claimed optical resolution -- 4800 ppi -- I felt that the maximum level of detail hadn't improved by all that much. This is because most all flatbed scanners -- even the good ones like the Epson V7xx series -- pretty much top out at about 2400 ppi maximum resolution.
Don't believe me? Do this then: scan an image at 2400 ppi, then scan the same image again at 3200 ppi. Then using your favorite image processing software, resize the 2400 ppi image to 3200 ppi so they're both the same size, then increase the magnification of both to 100% and see if you can find any difference in sharpness between the two images. Chances are you won't be able to. If you can, congratulations, you have a good scanner. But all this means is that your scanner scans at a resolution higher than 2400 ppi. Still, that is very good for a flatbed scanner.
I also own an old HP S20 35mm film scanner that's good for 2400 ppi. It just edges out my 4990 in terms of maximum resolution. But even with its scans I could see that there was still more detail to be extracted from my slides.
2400 ppi wasn't enough for me. So in my continued quest for more resolution, I bought an Opteka slide duplicator, which is attached to the front of a lens, and which contains an optical element to achieve close focusing. This worked, but because I was using a 1.6x crop body camera, it required the use of a zoom since it worked out to approximately 70mm for 1:1 dupes. And the duplicates were only as sharp as that zoom plus the correction lens.
Finally, I modified my rig by removing the Opteka's optical element (it just unscrews), threading the copier barrel onto my 55mm f/3.5 Micro-Nikkor (thankfully, it has 52mm threads), and using 30mm worth of extension tubes. At last, this gave me 1:1 dupes with no other optics in the light path other than the Micro-Nikkor.
Here is a shot of the slide I used for comparisons. It was taken in 1989, Fujichrome 100, Canon F-1 with a Canon FD 50mm f/3.5 macro lens.
These are the results. The camera for the two slide dupes was a 10.1 mp Canon XS (1000D). 100% crops for the ones using the Opteka, 50% crop for the Epson 4990. No post processing of any kind were done.
Epson 4990 scan at 4800 dpi
Opteka slide duplicator with element and Canon EF 28-80mm lens
Customized rig using Opteka, 55mm Micro-Nikkor, and 30mm ext tubes
If we can ignore the differences in color balance and exposure for the moment, we can see that the dupe using the Opteka with element is clearly sharper than the Epson 4990 scan, and that the rig using the Opteka with the 55 Micro and extension tube is even sharper than the Opteka with magnification element that was attached to the 28-80 zoom. The last image does look a bit overprocessed, though. I think I may have had the camera's sharpness level turned up a bit too high. Still, you get the idea. It's pretty obvious that using a slide duplicator rig something like what I put together does a clearly better job than even a good quality scanner.
With my camera's 10.1 mp of resolution, the above dupe works out to right at 2600 ppi. So, if you have a 7D, then you're looking at, what, 80% better than this? A 5D II will be like 120% better? Even at 2600 ppi, I'm already resolving the grain of that old Fujichrome 100 emulsion.
And speaking of the rig, here it is -- showing both the slide and roll film stages.
The Opteka duplicator shown (attached to the front of the Micro-Nikkor lens) is a model that has since been discontinued, which is a good thing, because the way the slides were mounted was not good. You can see that I've dismantled the end of it, and what I use now for slide and roll film stages I took off an old zoom-slide duplicator I bought off ebay for about ten bucks. The "digital" slide duplicators I see for sale now have a better slide mount, and many offer a film strip guide as well. Better than what I had to deal with, certainly.
Regarding negatives, it's easy to dupe black and white. Just reverse the dupes in your software. But color negs are trickier because of the orange cast. I've been successful with a handful of color negs, but many -- most -- give me fits. I've even tried at least one PS plugin that's supposed to automate this process but it didn't do any better of a job than I've been doing. One person suggested setting the white balance to the orange mask and then shoot the dupes. This might work, haven't tried it yet.
Regarding exposure, there are basically two ways to go so you don't have to futz with white balance: use a white posterboard for a reflective surface and then shoot your dupes during mid-day hours, reflecting the sun's rays off the posterboard. Or an off-camera flash. I've done it both ways, and I find the flash to be way more convenient. I have a manual setting on my flash. I set it to 1/32 output, which enables me to locate the front standard of my rig about 10" away from the flash for correct exposure. If I need to correct exposure either way, I just move the camera closer or farther away from the flash. I have the flash mounted to a light stand, and I hand hold the camera.
Doing it this way, assuming I don't have to clean each slide before shooting it (a big assumption), I can dupe 3 to 4 slides a minute. With the above scanners, it takes 3 to 4 minutes per slide.
This was a pretty economical rig for me to assemble. I already owned the 55mm macro lens. The extension tubes I bought off eBay for $8. Just cheap tubes with no meter coupling. The Opteka cost me about $60 off eBay. The slide and roll film stages I also got off eBay, but the new duplicators are such that these likely won't be necessary. The Nikon F to EOS adapter was about $15 off eBay as well. If you have an FF camera like a 5D/5D II/D700, then if I were you, I'd spend a bit more, and get a set of bellows with a slide duplicator.