Last year I drew a L.E. elk tag here in Utah, so I decided to invest in a spotting scope. I purchased a Leupold Windriver because I didn't want to spend more that $250 dollars. Turns out I was very disapointed with it. The Windriver is 15-45X 60mm lense. While scouting, I found that trying to view bulls using any setting beyond 15x was worthless even at distances under 1000 yards. It does not have enough light gathering power for anything beyond 15X. The more you zoom in the darker and blurrier the image becomes.
I took it back and purchased a Nikon Spotter XL 20-60X 70mm and just love it. It is priced at about $500 but made a big big difference. I went back to the same spot and watch the same elk which I previously could only tell were bulls. If fact there was one elk that I could barley make out was a bull using the Windriver. Viewing the bull in the same general area with the Nikon I could clearly see his antlers and determined he was a 360+ bull. With the Nikon, I could clearly see elk beyond 1 mile, In fact I watched 3 bulls one evening that were about 4 miles away. Of course, at that range there is not a great deal of detail but I could clearly see there were nice bulls. Very impressive.
If possible, I would recommend spending a little more $$ it's worth it. The saying you get what you pay for is very true.
There is nothing more frustrating than seeing a bull but not being able to determine how big he is.