[DonRotolo]

In the KoP there is a baggie with, among several things, a few feet of the retro-reflective material. Find that and make a target from cardboard (any color, even white or brown). Use a light source next to your camera (a small flashlight is fine, maybe LEDs on a competition robot). You will see a huge difference in light vs dark.

Or, saying it another way, it takes 5 minutes to fabricate a vision target that is very close to the real thing. I am suggesting you do that. Make sense?