If you need to scan a slide, negative or some other transparent
object, but your flatbed scanner does not have the special accessory
lid normally sold for this sort of job, then read on.
Last weeks issue of “Amateur Photographer” descibed a commercial
device that enables any transparent object to be scanned. Beter stil,
the principle is so very simple that you can make it yourself. It is
essentially a “string and sealing wax” job.
You need two small mirrors, say the size of a music cassette or
thereabouts. It helps if they are the same size. With the mirrored
surfaces touching, arrange a hinge of some sort along one long edge.
Tape is fine, but if the mirrors are not in a plastic frame beware of
pulling the mirror backing off when you dissmantle it … low tack
tape helps. Now arrange the mirrors like a tent on the bed of your
scanner. The mirrors need to be at 90 degrees to each other, with the
mirrored surfaces underneath (towards the scanner bed), and the hinge
aligned with the direction that the scan head moves. It is convenient
to use Blue-Tack or modelling clay on the bed to hold the mirrors in
place. They will need adjusting to get the angles just so.
What happens during a scan is that light comes up through the bed,
reflects off the first mirror, travels horizontally to the second
mirror and down through the slide to the detector head.
To set it up, leave the lid up out of the way, and do a quick scan.
Most likely you will just get a poor image of the mirrors. They need
to be adjusted until the area beneath the mirrors is filled with
bright even light when scanned. A bit of trial end error. When you
get that, pop a slide underneath one of the mirrors (not on the centre
line of the “tent”) and away you go. Do a quick preview, select the
scan area to include only the slide, set the controls for maximum dots
per inch and away you go.
Adjust the image in Paintshop or whatever, reverse a scanned
negative. Even with ordinary mirrors the quality is really amazing.
For critical applications I suppose you would need optically flat
glass, mirrored on the front surface, which is what the commercial
device has, but then it costs UKP 57. Have fun.
Kevin Eva, UK