Quote Originally Posted by BetterSense View Post
Of course it's relevant. If two things appear to be the same tone but one of them measures several stops brighter then you know something is up. Especially when it's something known to emit lots of IR (grass).
I do NOT want to start a battle here, I'll only TRY to repeat, once more:

I will NOT accept, as some sort of proof, assumptions about IR radiation (Infra = "unperceivable") based on VISUAL PERCEPTION.

"Something known ..." (deleted).

Grass doesn't "emit", anyway. It only reflects... and if there is not much IR to start with, not much will be reflected.

Yes, and using a complementary colored filter to "even out" the red-leaning response would be a good idea, but I don't know where to find color gels or information on their transmission spectra.
What purposee would this "evening out" serve? You are close to Extended Red IR film.... "Evening out" would only be useful if you are to use conventional black and white, or color film.

As I've said, try the Tiffen or B&W (preferred) catalogs.