Recall which feature makes electron microscopes different from both compound light microscopes and stereo light microscopes.

The key feature that differentiates electron microscopes from both compound light microscopes and stereo light microscopes is the type of illumination used to view the specimen.

1. Compound and stereo light microscopes use light waves to illuminate the specimen. They work by passing visible light through the specimen. Different parts of the specimen absorb or reflect the light to different degrees, creating a contrast which can be observed through the eyepiece.

2. Electron microscopes, on the other hand, use a beam of electrons instead of light to illuminate the specimen. The wavelength of an electron beam is much shorter than that of visible light, which allows electron microscopes to achieve a much higher resolution and magnification than light microscopes.

3. This means that electron microscopes can reveal the structure of much smaller objects, including individual molecules, which are far beyond the reach of light microscopes.

4. Additionally, electron microscopes have the ability to create three-dimensional images of the specimen, which is not possible with light microscopes.

So, the main feature that makes electron microscopes different from both compound light microscopes and stereo light microscopes is their use of electron beams for illumination, which allows for higher resolution, higher magnification, and the ability to create three-dimensional images.