How you use a slide viewer might vary depending on your slide viewer’s specific design. However, the method is pretty straight forward and common among most devices. Start by placing the film inside the slide viewer through its slot or a film holder. The viewer will then emit light which, shines through your film and projects it on a surface like a ceiling or a wall. Modern designs usually have LCD screens where you can see the digital image as well, and perform edits on it. They also include a scanner that converts the image into a digital format, which can then be stored in its internal memory or an external SD card.