Originally posted by stepmac I hear that one can take a digital picture of a slide placed on a light table. Is that true? Has anyone tried such a technique? You are supposed to place sheets of paper on either side of the slide. Seems like it could work...but does it?
I'm only on my third roll of film, which I'm scanning on top of a light table, but maybe this will be useful. Here's my basic setup, from bottom to top:
- Light table
- Cardboard mask to minimize light that doesn't go through the negative
- Filters (020 and 021)
- Lens hood
- Negative holder for obsolete scanner with the negatives
- Macro lens
- DSLR
- Tripod
The cardboard mask makes a huge difference in image contrast. I went from using about 40% of my K-5's dynamic range up to about 85% just with this trick. (Rough estimates from looking at the histograms.)
The filters compensate for the orange mask on a negative; you won't need these for slides. They're important for negatives, though, both because they relatively decompress the blue channel (resulting in less digital noise) and because they get the white balance close enough that you can use the eyedropper in Lightroom.
The lens hood is used to move the negative away from the light table, in hopes that any dust or irregular illumination will be blurred out. An inch or two is fine, given that depth of field is very shallow at this magnification.
The negative holder keeps the film flat. This won't be necessary if your slides are mounted.
The camera is suspended from a tripod with the center column inverted. I use a carpenter's level to ensure the light table is level, and a hotshoe bubble level to ensure the camera is also level. If they're both perfectly level, then the sensor plane will be parallel to the film plane.
I'm perfectly happy with my 8x12 print of a 135 negative "scanned" using a Takumar macro (the tricycle shot posted earlier in this thread), but that image didn't have a lot of fine detail in it. The magnification there was a little over 2, so a lot of the frame was cropped. Moving to the tripod gives me the working distance for a 100mm macro and crop-free magnification of about 1.5... and if I want more data from the negative, I can go to a 1:1 magnification and stitch the images together like a panorama.
Here's from today's scanning project (click for bigger)