How to Use a Digiscope Adapter
A digiscope adapter is used to attach your camera to the eyepiece of a spotting scope. The usual type of adapter available in the market is a tube-type which fits over the eyepiece at one end and you camera at the other; both are secured by screws.
Using a Digiscope Adapter
Now, many digiscope adapters are available that have 28mm thread, so that you do not require any step down ring to fit filter threads on Nikon cameras. Such an adapter will reduce vignetting, as the camera lens comes almost 2mm of the eyepiece. While using direct thread attachments, you need to handle you camera with care, as there is a chance of damaging the threads on your camera.
The digiscope adapter is easy to use, as you just need to slip one end onto the eyepiece of the scope. You insert the lens of your camera onto the other. Usually, there will be three to four screws which need to be tightened, which will secure the camera to the eyepiece. The screws should be tight enough to hold the camera firmly, and at the same time not too tight as to damage the camera lens body.