Glossary, Or: how the technical terms are used in this overview of theoretical information, practical recommendations and hints

The following terms will be used to describe the act of reproducing the three-dimensional object that constitutes a lantern slide.

– scanning = activity done by an operator using a scanner: the reproduction of a flat, mostly transparent object with the help of an internal light source that sends light rays through the object directly onto a light-sensitive surface (sensor) which receives them progressively during one or two seconds (when done “line by line”) or at once (when the whole area is illuminated); the scanner transforms the captured analogue information into digital data and transfers these to a computer which stores them and shows the result on a monitor.

– photographic reproduction  / photographing = activity performed by a photographer using a (still-) camera: the reproduction of a two- or three-dimensional object with the help of external light sources to illuminate its surface (reflection) or shine through its body (transmission), the produced light rays fall through a lens and are captured instantly by a sensor; the immediate transformation of analogue into digital information and the storage of the data inside the camera allow that the reproduction can be seen one or two seconds later on the camera’s monitor.

– digitisation = the act of transforming the image of an analogue artefact into a binary code by electronic devices (scanner, (still-)camera) and to reproduce it as a simulation to fit a digital environment (internet, computer, beamer).

– archive = this includes all institutions that keep slides, whether they are museums, private collections, libraries etc.

– slide = the word is used in this context to keep in mind its function: to be projected by sliding it into the light beam. (In the 19^th century some manufacturers also advertised them as “sliders”.) This use distinguishes it from other pictures on a glass plate, e.g. “reverse glass paintings” (Hinterglassmalerei) or autochromes.

– 1:1 reproduction = the process of digitisation in our context has to lead to a faithful reproduction of the artefact. 1:1 means that all has to be done during the working process that the reproduction has the same light and colour values as the artefact that is exposed to the device. Of course, to achieve a 1:1 reproduction is theoretically impossible as the translation of material information into binary codes influences the appearance of any object. Nevertheless “1:1” is used to stress the intention of the activity: to regard the digitisation as a means to depict the slide in the most authentic form possible that, if one day the artefact has deteriorated or is lost, future generations can consider the information contained in the file as a faithful reproduction of those that characterised the vanished material.