The Automatic 543 is the model of the projector that takes this tray.
A camera, a photocopier, and a slide projector all use lenses to perform their functions.
Slide projectors are considered "old technology", but if you have slides and a projector, showing them would emphasize that you and your dad predate PowerPoint. And that's not a bad thing.
All 500-series Argus projectors can use the 587 tray. It holds 87 slides.
All 500-series projectors can take the 593 tray.
All 500-series projectors can use the 581 tray.
There are a number of publications that frequently use "The Argus" for a name. Some examples include The Argus of Fremont, California and The Argus of the Bay Area.
Most slide projectors use mounts that are 50mm x 50mm square with an image that is 24mm x 36mm. The image can either be in landscape view, wider that it is high or in portrait view, higher than it is wide. The shape of the image on a screen is dependant entirely on the way the slide is inserted into the slide magazine or into the gate of the projector. Lenses are no different for the two views.
Some advantages of using a slide presentation is the ease of use and the ability to maintain eye contact due to the lack of needed handouts. Disadvantages are that slide can oversimplify complex topics and the cost of the equipment needed to run a slide presentation.
" Go get me that projector, please".
You could use welders goggles. Or you could use a projector such as a pin hole projector.
Large projector screens are used in several places today. Movie theaters use projector screens, large conferences use projector screens, and you can even rent or purchase projectors and screens for personal use.