Would you have thought that you could mount a camera or a spotting scope on your equatorial mount? With a camera adapter for the right mounts, all this is possible.
This way you can mount not only your spotting scope or camera, but also any small telescope with a photographic attachment (e.g. 80/400 refractor, 90/1250 MacSutov-Cassegrain)
1/4" threads can be easily attached to any camera, and the 3/8" thread is used to connect photo tripod heads.