Fully Adjustable Microscope Adapter

Video films of complicated dissections can be great teaching tools. Especially since HD cameras
have become affordable, it is possible to record step by step instruction at a resolution that actually
allows to see what is done.

A surgical dissection microscope maintains stereo vision for the operator during filming as the light path
for both eyes is equally affected by the mirror splitting off light for the camera port. One problem, however,
remains: with commercially available adapters (we have tried several...) the field of view and focus of the
camera rarely match those of the operator. While it is impossible to achieve 100% identical coverage
(the eye piece projects a round image, the camera view is square 3:4 or 16:9), it is very helpful to adjust
the field of view in a way that the operator can comfortably move tools and dissection without having to
constantly monitor the field of view of the camera.

The camera adapter built also allows for X-Y translation (Fig. 1). After the initial tests it quickly became obvious
that the microscope's camera port is offset with respect to the field of view of the eye-pieces. The adapter
contains a single lens which proved satisfactory in image quality, introducing only minor distortions. The image
the camera sees can be focused by sliding the outer focus tube over the inner tube. Together with the zoom
and focus functions of the camera, this arrangement allows to set the camera's field of view in a wide range and
to match it to that of the operator. All parts of the adapter are made from solid brass stock (Fig. 2). Different
top-pieces allow for different cameras to be mounted, all of which are lightweight (<1 lb) and do not require
additional mechanical support (Fig. 3).

Figure 1: Drawings of the parts used in the adapter

Figure 2: The individual parts including C-mount adapter and two different camera adapters

Figure 3: The adapter in use on a Wild stereo dissecting microscope. The camera mounted is a Canon HV10 HD video camera with 2.96 megapixel CMOS sensor.