Re: how to determine power level
There is also the factor of Mirage. In some instances, mirage and heat waves coming up off the ground or the barrel can be so bad that we have to turn the power down to get a clear and sharp focus on the animal. Personally, I feel that 24X and higher is best served on paper during load development or maybe some competition shooting. 14X to 22X is what I prefer on the top end for hunting. I've had no problems shooting sub 1/2 moa groups with 14X to 22X power either, so long as the rifle/load are capable. Most will probably say that 32X is a waste for hunting purposes.
As stated above, field of view is important when hunting, especially if we don't have someone along that is willing and capable of spotting our shots for us. Much easier to see our own hits in 14X than it is in 32X due to the greater field of view.
Aim small = Miss small