Pete Dixon

In case it isn't obvious, the cell phone sits inside the device and held in place by a spring. Above the holder you can see sort of a hole. That's where it is positioned on the microscope eyepiece. The screw is then tightened to keep it in place.

The next trick is to swivel the cell phone such that the camera is looking down the microscope. You can't see it from the picture, but there's a track that moves up and down, so wherever the camera lens happens to be on your phone you can line it up properly. Setting it all up just takes a couple of minutes. I had to remove my cell phone from its case for it to fit between the guides.