MicrobeHunter.com Microscopy Forum

Very good book on how light microscopes work.
Explains just about everything: Light, colour, filters, lenses, image formation, illumination techniques etc...
It is effectively a textbook on the subject.
I recommend one dip in as needed rather than attempt a read through.

http://www.biology.uoc.gr/courses/BIOL4 ... s/book.pdf

Another great book- Practical Digital Photomicrography by Brian Matsumoto. It's mainly about how best to use the equipment- the lens, digital cameras and how to mount them to the microscope, improving the images, and buying a microscope. It's an excellent book for the informed beginner.