ORIGINAL: MeanV2
It takes some extreme situations before it is necessary. All it takes is a little math to figurethat out.
Dan
Mountain goat at 45 yards by your rangefinder at about what you figure to be a 55 degree down angle. What do you shoot him for? (Jeopardy music in background...)
Is your angle estimate accurate? Do you carry cosines in your pocket? Point is that it's more than just a little math on top of a bunch of other stuff you've got to stop from going wrong. They are definitely worth their weight and expense in those extreme circumstances.
ps.) (COS 55)(45) = 26 Hard to trust it but if you do... Bam! dead goat.