Exposure Tester

This is a tool to test the exposure time of a camera. I have a trail camera that I suspect is taking much longer exposures than it is claiming, so I built this to test it.

The idea is to have a rotating pointer that the camera will take a picture of. If you know exactly how fast the pointer is rotating, you can calculate how long the exposure is by measuring the angle the blurred pointer covers in the picture. To make measuring the angle easier, there is an LED at the center of rotation, and another at the tip of the pointer.

I built the pointer in FreeCAD, but when I went to build the mount, I wanted to use a threaded hole. I looked up how to create threads in FreeCAD, and found it was really complicated. So I made the mount in OpenSCAD where I had already created spiral_extrude(). This made creating the threaded hole much easier.

To make the mount, you will need to also download spiral_extrude(): https://www.thingiverse.com/thing:1958354, and edit the mount.scad file to tell