For anyone interested in microscopy with a Pi and camera board, please have a look at my web page and click on the link to the raspberry picroscope
http://personal.ee.surrey.ac.uk/Persona ... index.html
Without repeating too much of what is there, I took on an intern student for a week and his project was to adapt the Pi camera board to an optical microscope. It worked very well indeed as you can see from the images and it saved us best part of £2k in the process. I've attached an image from the site of the camera on one of the microscope C-mounts, other images of the set-up and from the microscopes themselves are on the link above.