For a long time I have had a fairly simple test for my scopes. Two part test. When it's past legal shooting time the first question is how far can I see something I might shoot under the best the scope provides. A scope that gives me 200 yards is always better than one that gives me 100. The second question is how long does it take me to decide I can shoot.
The first test "measures" brightness, reticle,resolution and color fidelity one way, The second measures both by comparing how well my brain can make sense of what I see and what is actually being presented.
A scope give you a two dimensional picture with a limited depth of field. When you look at an animal with just your eyes, sometimes your eyes are better than the scope and sometimes not and usually low light conditions will aggravate poor perception. Contrast and color fidelity provide very important clues to your brain.
An example: Hunting under heavy canopy, like in a tamarack swamp here, late on a cloudy day. You see two deer, one facing left, the other right, standing one behind the other. Your brain can have a very hard time making sense of the picture even though you absolutely know you are not looking at a Pushmepullyou escaped from a Dr Doolittle movie. A scope might just make that problem worse if it provides a low contrast shallow depth of field view. Distance judgment when your brain cannot resolve the picture goes right straight into the toilet.
Critical distinctions like body angle probably cause a lot of bad hits and lost deer that people swear up and down were dead solid good hits, and those distinctions are even easier to lose than the example above. The scope must provide not only a bright picture, but one with sufficient color fidelity, contrast and depth of field to help your brain make sense of the picture. And, it must be sufficiently helpful that you can decide to shot, not shoot and where to place the shot in the time the animal is giving you.
Targets are vastly simpler to handle. The are almost invariably high contrast. They are just about always decently lit. They are one dimensional and you never need to worry about their angle. You never have to worry about is it a big target or a small target and you know the range.
