Is there any difference in the amount of light that a straight lets in over a angled spotting scope ? And other than your not look right at the object throw a angled is that the only difference in scopes?
Most angled spotting scopes have all the same parts as the straight ones .The only difference is that the Prisms are located on the center line of the rotating joint so it can be positioned at different angles.Some angled scopes are fixed at a specific angle but they still have Prisms to shorten the
overall length of the scope.
There should be no light loss over any scope that uses Prisms.