Digiscoping with the GR
Has anyone tried digiscoping with the GR? If yes, can you provide the name of the adapter?
With the wide angle of view of the GR, why would you want to attach it to a "fieldscope"? You are almost guaranteed to have vignetting. A "Normal" or "Telephoto" lens will work better.
If the issue is to have an APS-C sensor, then any interchangeable lens APS-C camera, mirrorless or dSLR, will be easier to adapt. The same is also true for micro-4/3, Pentax Q and 1 Nikon. The Q and 1 Nikon have the advantage of small sensors that will minimize the issue of vignetting and create defacto greater magnification with your scope.
Nikon makes a dedicated adapter for the 1 Nikon system and their fieldscopes. The issue with the Nikon adapter is finding the Nikon Eyepiece that best works with your scope and the adapter.
If you wanted to adapt the GR, then you will need the GH-3 adapter and hood. You will use the adapter to give you a flange to attach the scope to the GR. You will not use the hood.
The GH-3 adapter will give you a 49mm thread to work with.
You will then need an adapter to go from your scope's eyepiece to 49mm thread.
There are many variables.
You will need an adapter similar to this one:
I suggest that if you go this route, after you get the GH-3 adapter, message the ynoshk ebay store and ask for recommendations.