I don't think they can see fluorescent orange, at least I've ever known them to notice the orange. I've always been told that deer see color almost in black and white, not truly color blind, but more adapted to see in low light, and no light situations.
Deer hunting clothing is big business, what they can and can't see has been studied to death. The different colors are due to the wavelength of light, the blue end of the spectrum are short and the red end are long wavelengths. Deer can see the blue end better than we can, don't wear blue jeans when hunting. But the other end like red or orange is just grey. Green is seen pretty much as a grey, at least it won't stand out, especially when in camouflage. Green camouflage is a good color for deer hunting and other game hunting. Green/tan camo is probably so popular because it works for so many different animals.
Hunter orange is not common in nature and humans can see it really well. It really stands out to people so it has saved a lot of lives without alerting deer. So you buy basic camo for all hunting and add and orange vest or cap for deer. Different states have different requirements for how much orange.
Well Black powder season is officially over, and Modern firearms season is in. Last few days of black powder were pretty interesting, deer are starting to move really good, Rut is kicking in down here. My grandson and I went this past Thursday and killed a decent buck, we had deer running all around us, he got to see a few young bucks chase the lady's around. Then a bigger body deer hit the field, he said poppa Big deer, normally I would have chosen to pass on this deer, but I knew this was as good a time as any to get a buck on the ground with my grandson. So we smoked him! he tipped the scales at 151 lbs. My grandsons 3rd deer hunt, with 2 deer on the ground.
My son went yesterday afternoon, he said cold fronts moving in, the deer should be on their feet, I told him ought to be a good day, cloudy and overcast. Well, he had this big guy on the ground before dark, tipped the scale at 175 Lbs. I've got 2 curing out In the cooler now, I'll start processing these Sunday, My sons off next week, and Im off thanksgiving week....lots of venison fixin to hit the ground stay tuned.
This week a 76 year old client was sent to hospital by a buck. He attacked her in her own backyard. She was feeding him and others, not sure why he attacked but hurt her bad. Broken pelvis. Deer are never hunted here so have zero fear of people.