Huh? To my knowledge the rods and cones in the retina vibrate in a specific bandwidth which determines what light frequencies register in the brain. The brain receives stimuli, not frequencies/photons. The only way this can be determined with a deer, IMO is via trial and error by shining different light wavelengths in the deer's eyes. Then the deer can tell the scientists what light it can see or not see!
That won't work. Deer lie.