Slide projectors are the opto-mechanical device that is used to project photos as a slide show. Carousel slide projector is the most common of them. These were used in the 1950s and 1960s as a source of entertainment for the family. They were used to project slides on to the wall or a screen so that a slide show can be viewed. Louis Misuraca was the inventor of this device. This was sold to Eastman Kodak Company and Louis did not get his royalties.
The physical form is circular. This projector has a separate tray holder that has to hold several photo slides (35 mm slides). The numbering is usually from 20, 36, to 140. The slides are placed upside down and backwards for the image to appear straight on the screen. The body contains a rotatory motor that is used to rotate the tray. There is a built in mechanism to drop the slide once it is projected and to load another slide.
The most famous of the 35mm projectors are the Kodak and Etktagraphic projectors. They were introduced way back in the year 1962. Less known brands include sawyer, view master, etc. these had a carousel in a Ferris wheel like position. Some projectors are just like boxes without the carousel form but they run on the same mechanism. These projectors had lot of advantages over the ones available in the market at that point of time. They are discussed below.
The first advantage is that the carousel tray was the best one to project and transfer the slides. This had a locking mechanism and this prevented the slides from slipping and falling. This system was largely appreciated. Then there was the use of gravitational force to lower the slides. They were lowered on to the projector lamp and this was a good idea. This is because use of gravity reduces the chance of jamming by leaps and bounds. The use of a circular tray also was a path breaking feature that enabled automatic shows without the need to reset the tray when the show needs to be repeated. These advantages made Kodak the market leader in the selling of these projectors.
But since the late 90s these projectors lost popularity with the advent of digital systems and more sophisticated lamp projectors. Just as conventional cameras are being out-dated, these projectors are also no more in use now. There are a few models available for sale. These models are all second hand ones. Only a few people still use them. This is due to the upgradings of the technology. No one needs a projector now to view slide shows. Everything has become computerized.
Kodak discontinued the production in 2004. Since then these models are available as vintage pieces. Still the aura and the special features of these projectors don’t lose their speciality. That is the reason Digital Scanners are being brought to scan the slides and convert them to digital format. There is a chance for you to own these slide projectors. There are for sale in most of the online marts.