Saturday, March 25, 2017

Scanning Lantern slides

19th Century Magic lantern
 projector Wikipedia

Some time ago a client approached me about digitising a collection of early lantern slides.  Lantern slides are squarish glass slides that contain a mounted photographic transparency and are designed to be displayed in a magic lantern projector. Magic lantern projectors date back to the 17th Century and use a concave mirror at the back of a light source to direct the light through a lantern slide onto a lens which is adjusted to display the image on the slide onto a wall or screen.  Early lantern slides were hand painted images, then later the slides were printed using either photographic or photomechanical processes.

Lantern slides are positive images made from a negative. The image is mounted on a glass plate and covered with a glass cover which is taped at the edges. Lantern slide shows were either for entertainment or educational purposes. My client's slides dated from the 1920s and were black and white photographic images her Grandfather used to illustrate a presentation he made to the Nelson Literary Scientific and Philosophical Institute.  The slides and talk were about the hill tribes of Assam in north east India where he lived for some years.

Oridinary scan of image captions
Scanning the slides involved a two stage process - a reflective scan to record the image surround which contained important image captions and a second transparent positive scan.  In the second scan the scanner light is transmitted through the slide in the same manner as a magic lantern. The combination of shining light through the slide; the fact the slide sits directly below the scan head with no additional scanner glass and the auto focus function, enables a very clear high resolution scan.  Lantern slides are encased in glass so it is important to identify the emulsion side to get a clear scan.  Like glass plate negatives Lantern slides need to be handled carefully with gloves to avoid fingermarks and breakage.

Slide Scan
Final image

Final image
Final image

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