5,0 MP MicroQ-PRO digital microscope eyepiece (USB3.0 , CMOS, colour) with software for measurements

 These cameras have great image quality, available between 3.0 and 14.0 Mp resolution. They have standard C mount connection, many adapters are available for different microscopes.
These new models have USB 3.0 connection, which allows much faster video frame rate (frame/sec) at higher resolutions.

An excellent and easy to use software comes with the camera, which makes it possible to measure distances, angles, area sizes even on the live view. The recorded video can be resized and also differently sized and shaped markers can be overlaid, helping the measurements later.
In this price range the "Manual fusion (make image large depth of field)" function is an excellent addition, which lets anyone to increase the depth of field by adding up to 10 layers to the final image.