Microscope photos can be obtained by mounting an infinity corrected microscope objective lens on the front of a standard camera lens. I recently obtained an Olympus PLN 4X for this purpose. These objective lenses are designed to work in front of a "tube lens" (i.e. camera lens) of about 200 mm focal length that is focused to infinity. The two 200 mm camera lens options I had were the 70-200 f/2.8 zoom and the 105 f/2.8 macro lens fitted with a 2x converter. The zoom lens suffered from some minor vignetting issues, so I settled on using the 105 mm with 2x converter.
See the photo at the end for the setup. Several adapter rings are required to arrive at the thread size of the microscope objective lens. The camera and lens is mounted on the KT-70 table as described at the Focus Stacking Hints page.
The first set of photos are of a One Baht coin. These are taken with the 105 mm + 2x set to infinity and closest focus respectively, and correspond the imaging width are about 6 mm and 3 mm. Although the microscope objectives requires the camera lens to be focused at infinity, it also seems to work OK at close focus to give an apparent increase in magnification.