The microscope adapter needs a single screw to hold the camera to the mount. I used the same aluminum knob as on the adapter for my previous camera, shortening the screw so it didn’t bottom out in the camera socket:
The boss is slightly shorter than the recess, so the knob body seats on the plate and works like this:
When the camera isn’t on the adapter, the screw stores neatly in the 1/4-20 nut sunk in the middle of the mounting plate.
Although I can hand-hold the macro lens adapter, it’s much more stable on a real tripod. That requires a flat camera-mount screw that sits within the recess so the mounting plate can sit flush atop the tripod head:
However, it’ll be much easier to use the knob screw when I’m hand-holding the thing, so I drilled-and-tapped a hole in the knob for a place to store the flat screw when it’s not in use:
The threads in the knob don’t go quite far enough to seat the screw head against the knob, but that crude hack wouldn’t work in aluminum. Fortunately, it doesn’t matter:
This being a low-torque application, I filed the top off the already-pretty-flat truss head so the mounting plate recess didn’t have to be all that deep.
The knob+screw stores in the 1/4-20 nut between uses, too:
Yeah, yellow probably isn’t appropriate for an optical structure; I’ll shoot a black rattle-can coat inside there after the weather warms up…