I have a Kowa Prominar TSN-884
Awesome glass!!!
Question.
What percentage of the higher priced glass is used in the Prominar model scope, and where is it located?
Does the eyepiece have the more expensive glass also?
Or are the eyepieces the same glass in all models?
Did you compare a prominar model with a regular model on the same day looking at the same things?
Unless things have recently changed in the manufacturing of all brands of scopes,
only the inner element of the objective lens will have the higher priced glass.
All other glass used in the scopes will be the regular glass, as will the eyepieces.
Advertising laws permit scope makers to (imply) that scopes have the more expensive glass, even though only a small percentage of it is actually used in the scopes.
It is not as durable in standing up to abuse as the standard glass, which is why it is used only in the location it is used.