Digital Projection Format
Q) When it comes to moving from the traditional slide projector to digital display media, I'm frustrated because all the projectors I've looked up have a display format ratio similar to computer monitors. The good old slide projector projects a square format and allows for portrait photos to have the same display area as landscape. This isn't the case with the digital projectors. Consequently, the size of all portrait pictures are limited to the (shorter) height of the display media. The pictures are, therefore, displayed at different sizes. Do you know of digital projectors that have a square display area like traditional slide projectors? Is there not enough demand for such digital projectors for the industry to develop such a product?
A) Projector manufacturers originally developed these units for PowerPoint displays and weren't considering photographers' needs. Unfortunately, I don't know of any square digital projectors.
As to your last question, you have to examine the differences between manufacturing a slide projector and a digital projector. Instead of projecting light through an image provided by your transparency, the digital projector has to re-create the photograph on its imager.
The imager used in the digital projector typically is a piece of highly complicated silicon. The manufacturing line for producing this silicon is called a foundry, and foundries are very expensive to create and run. Manufacturers have to appeal to a wide market in order for a product to be profitable. Until the market creates a significant demand for square-aspect projection or the imagers become very inexpensive, the standard 4:3 horizontal rectangle will likely be the only way digital projectors will be sold. This situation probably won't be helped with the advent of high-definition video, which has an aspect ratio of 16x9 (a horizontal rectangle).