Only way to tackle this problem that I know of is to think about...
1. How far do you want to view?
2. Think about how much magnification you need/want per 100y (i.e. 1x, 2x, etc.).
3. Consider 2mm exit pupil as the bare minimum.
Let's say you want to view out to 2000y, and want a minimum of 2x per hundred yards. Based on this, you need 40x. To keep the 2mm exit standard, you need an 80mm scope.
In the above example, you ain't getting the image you want/need with a 50mm scope. Just ain't gonna happen.
Use your bino knowledge/experience to get started. Would your 8x binos let you evaluate antlers at 800y? Or are they better suited to 400y? How about picking antler tips out of tall grass at 800y? Optical quality is also a factor but you need to start thinking about this stuff sooner or later.
Everything else is a just guess until you break-down exactly what you expect of your spotter. For some people a mile is really far, for others its just getting started.
How far and how small of a viewing object?
Jason
Last edited by 4th_point; 12/17/14.
