It’s true!  You don’t need to have a lens attached to the body during a tethering session.  You can easily use your DSLR with a telescope, microscope or bellows, but there are some things to keep in mind.   1) Electrical contacts – DSLR lenses have electrical contacts that allow focus and metering data communication with the body.  Most adapters do not have this, so the body will not know if the metering or focus is correct.   2) Adapters – The length and diameter of the body-to-device