Here’s an oldie but a goodie. [RunnerPack] stumbled upon an article from 2001 about building a stereo microscope from a pair of binoculars and a camera lens. With a ring light attached to the ...

While much cheaper than standard equipment, there was a caveat: a microscope’s specially crafted glass lenses often cost hundreds of dollars, putting the tools out of many people’s price range.

In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.