Digital microscopy systems can cost thousands of dollars but a very useful model can be assembled by using one decent compound microscope and consumer products that cost less than $150. Many hopitals and universities have retired micorscopes that can be adapted to this task. The plans found here show how to modify a commonly found microscope. Many of these scopes have been retired in favor of more modern and ergonomically-friendly scopes. But these scopes yield suprisingly high quality images for the price. An older monocular scope can be converted to a wonderful teaching tool so long as the objective lens gives a good image. If the objective is marked with the infinity symbol it should work. We get great results with magnifications higher than 20X. For lower magnifications, you would presumably add a projection lens between the objective and camera.
The analog verison will plug directly into your TV monitor or LCD projector for display but will require an analog to digital converter to connent to your computer. The webcam version plug directly to your computer but the software can limit your creativity. After builing and using both, we prefer the quality and versatility of the analog version because it can be used with many free video viewer and recording applications available for Mac and PC.