BTW, danlisa, I just noticed your other post.
Yes, the colour of the TGA matters. It is my belief that SH3 sort of "mixes" the green colour with whatever colour the TGA is. Because the TGA is white by default, you get green... but if my theory is correct you could make the TGA red and then at night it'd be yellow!

(Edit: or, possibly, black again... depending on how it mixes it, and whether or not the colour is pure red, or red with a bit of green... oh, nm)
The binos don't change colour because SH3 doesn't add green to the bino bearing indicator at night, that's all.
Not that this is particularly useful, but there you go.