A bit of info on eyesight please?

[wadih]

When I did the test i mentioned earlier I was not checking their eye sight at all. I tried once the same experience guidofatherof5 talked about (throwing the fish) and it worked perfectly specially if the snake is excited about food (usually happens after the first fish). In fact I think they have perfect eye sight.
However, the test was to know how good they differentiate colors. And what I reached was that they do not differ colors a lot. I mean they see for example orange, dark yellow and red as the same color and so on.
But I am not sure if these results can be generalized on all thamnophis, and that is why I asked if someone got more info about it.

[Lovok]

When I did the test i mentioned earlier I was not checking their eye sight at all. I tried once the same experience guidofatherof5 talked about (throwing the fish) and it worked perfectly specially if the snake is excited about food (usually happens after the first fish). In fact I think they have perfect eye sight.
However, the test was to know how good they differentiate colors. And what I reached was that they do not differ colors a lot. I mean they see for example orange, dark yellow and red as the same color and so on.
But I am not sure if these results can be generalized on all thamnophis, and that is why I asked if someone got more info about it.

Your thread about whether they see colors or not was what prompted me to finally ask my question, even though I've been thinking about it some time beforehand. Sounds to me like they have some definite kind of color-blindness. I guess questions like ours would be better answered by someone who's got some herpetophysiology--yeah, I just made that word up--knowledge, and know how their eyes are actually structured (rods? cones? both? more of one than the other?).