Most commercial SEMs use electromagnetic lenses because they provide higher power (more drastically change the path of electrons) in a smaller space. The proble

Most commercial SEMs use electromagnetic lenses because they provide higher power (more drastically change the path of electrons) in a smaller space. The problem is that they require custom iron pole pieces. It's easier to build electroststatic lenses, which are just metal conductors and the geometry is not extremely critical. Search for Einzel lens for details. The condenser and objective lens in my scope are Einzel lenses made from copper pipe from the hardware store. I like the idea of looking at lead type with the SEM! The angle of the incoming electrons toward the specimen is what creates the viewing angle in the image. The angle of the secondary electron detector is what creates the apparent illumination direction. It's true that setting the specimen to split the beam and detector angles will provide a good image, similar to having a good key light in photography.