I have purchased the Kowa TSN IP5 iPhone 5/5S Digiscoping Bracket. I need the correct adapter ring for my Vortex Viper HD 15-45x65 Angled Spotting Scope. Can you tell me which one I need to order?
There isn't a Kowa adapter ring that will fit your Viper eyepiece, unfortunately. The eyepiece diameter is 48 mm. The closest would be the Kowa iPhone 60/66/82SV 30x Adapter Ring , which fits 49mm, and you may be able to make it fit by applying tape to the inside of the ring. But that isn't a perfect solution, obviously.
The other solutions would be
1. Phone Skope's bracket and adapter ring (go to the Phone Skope website to learn more), or
Sorry I don't have a better solution for you, since you already purchased the Kowa TSN IP5 iPhone 5/5S Digiscoping Bracket. Not sure where you purchased it, but hopefully it can be returned.