I wish to take pictures through my Televue Pronto using my α7R II camera. Is there an adapter to allow me to do this?
In most cases, we use a T-ring (42mm or 48mm) that is camera-brand-specific to connect to either a) the threads of the focuser tube, if it comes with threads
b) a generic standard size "T-adapter" which has male screw threads on one side that fit the T-ring female threads, and a "nosecone" on the other that slips into a focuser tube without screw threads. This nosecone will then be tightened by means of thumbscrews on the focuser tube.
I use a cheap eBay T-ring for the Sony E-mount for my A7S, which I then use both methods a) or b) depending on which scope I use. In your case, you can probably buy the required T-adapter from Televue, and find the matching T-ring online.