Slide Viewers & Slide Sorters

What is a Slide Viewer?

A slide viewer is usually a small handheld device with a slot in which a slide can be inserted to see a magnified illuminated view of it. A slide viewer is an instrument for individual viewing. Some models have an automatic feeder for inserting multiple slides and some have a slot for a strip of film. The slide viewer may rely upon natural light or incorporate a light source. 

Slide Projectors need some basic components to operate:  

• Electric incandescent lightbulb to light the slide  
• Reflector and condensing lens to direct the light to the slide  
• Slide holder, you remember those old carousels  
• Focusing lens to bring the slide’s image into focus  

Maybe you had an official screen on an easel that you could roll out during slide show time, or maybe you hung one of Mom’s white sheets on the wall. Either way, bringing out the slide projector was a fun family activity, as long as you weren’t looking at the slides from your uncle’s fishing trip to the Great Lakes for the millionth time! Ready or not, here we go! 

Turning on the projector activates the incandescent lightbulb, which lights the slide so the human eye can make out the images on the slide. Most slide projectors included a piece of heat-absorbing glass situated between the light bulb and slide to protect the slide from heat damage. You definitely don’t want that slide of your uncle holding up a 15-inch fishing trophy to melt away! 

A reflector, often a mirror in early models, would channel the light and the slide’s image through the convex lens.

The convex lens would then enlarge the slide onto the viewing screen (or sheet, depending on what you had around the house!) for everyone’s viewing pleasure! The spring mechanism in the slide projector would then advance the slides throughout the slideshow. Who wouldn’t want to see an entire slide show of grandma and grandpa’s trip to the grand canyon, slide after slide of rocks and dust? "