An M26 microscope objective lens is attached to the end of a Nikon telephoto lens (f=300mm) in combination with a step-down ring.
The image is formed and a clear image can be confirmed.
Distance adjustment dial on the lens side is a fine adjustment level
Project a glass scale with a pitch of 0.2 mm. The horizontal field of view is 0.4mm.
Magnification of about 800 to 1000 times can be obtained.
Incidentally, this method can also be used with a standard lens (f = 50 mm or so).
Since the magnification is reduced, ring illumination can also be used.
The focal length is about 40 mm.
The focal length is shorter than that of a dedicated microscope.