This is the adaptor from Zarf Enterprises which adapts any microscope eyepiece to the Coolpix camera.
The adaptor screws into the 28mm filter thread on the Coolpix, and the
other end tightens onto the eyepiece through an adjustable sleeve. The
adaptor is sturdy, beautifully made, and I can recommend it.
Although you can get by without an adaptor, it is easier to align the camera
with the scope eyepiece with an adaptor. You can also rotate the camera
on the eyepiece for best composition.