This is an inside review of the Nikon SMZ-1 - a Greenough-type stereo zoom microscope.
The eyepiece tubes (1) have rippled diopter rings to adjust for parfocality during zooming. The zooming knobs (2) for changing the magnification from 7x to 30x (in case 10x eyepieces are used). The focus knobs (3) can be turned in opposite directions to adjust the focus drive tension. Futhermore, the stage plate (4) has two sides - for switching between a black and an opal background.
Not an ideal construction: The microscope body is fastened onto the stand with a screw that leaves ugly marks on it.
The microscope body with the eyepieces already removed. The eyepiece tubes can be screwed out (there are lenses attached to the base):
Two small hexagon screws hold each zoom knob in place.
The two upper case halves (just plastic btw, not metal):
Under the hood, we see that each optical path has a set of three mirrors, each mounted on a movable plate (1). The two plates are movably connected together by a joint (2) which allows for easy adjustment of the interpupillary distance.
A 90° gearing translates the turning of the zoom knobs to the vertical axis with its sophisticated zoom mechanism.
With the lower case cover removed, the four pairs of lenses become visible. The optical paths are slightly inclined (Greenough-typical).
The following animation shows the zoom operation from two positions:
The SMZ-1 is an entry-level zoom microscope with almost no expandability (e.g. there´s neither a coaxial illuminator or a phototube) and mediocre optics. The field of view is small and the image does not appear too bright (going beyond 30x magnification does not make much sense imho). A workaround is a decent lighting system. Here I use two bright Cree high power LEDs.
Below, a sample image from a Drosophila spec. fruitfly photographed directly through a 15x eyepiece (low 10.5x magnification in the upper right versus the maximum 45x magnification).