The purpose of a spotting scope at long range is to read wind and mirage. To correctly read mirage you need to focus it between half and two thirds toward the target. If you focus the spotting scope at the target, you don't get a true reading of the mirage. In fact if you screw up and the focus is beyond the target you reverse the mirage.
So when your call says left wind, you actually have a right wind.
Plus: Too much power focused on the target is washed out by mirage. Added to that it picks up mirage from the heated barrel, further giving you a false reading.
Even with 10 X scopes, when shooting distance, I use a barrel band to break up the heat coming off the barrel.
I don't know why people insist on high power glass at long range. You don't need a clear target. An example shooting irons, if you are concentrating on the front sight, the target will be fuzzy anyway.
You can't see bullet holes at 1000 yards regardless of the power of the scope.
Another problem I've seen with using high power scopes, people tend to disregard their spotting scopes. Instead of checking conditions (which they can't see in the HP scopes) they end up chasing the spotter, instead of getting a reading for each shot. The last shot is history, when chasing spotters you are chasing history.
I don't know what type of targets one is shooting, but lets say its a man size target. You can see them quite well with lower power scopes. We were shooting to 1100 yards using M1C/Ds with their 2.2 power.
But that's just me, to each his own.
