Quote Originally Posted by BetterSense View Post
I don't think it was that the grass was green...but that it was grass. Vegetation always reflects lots of even near-IR; notice how it is aways white in IR photographs.
Not NECESSARILY true. The brightness recorded would depend - a whole lot - on the amount of IR radiation reaching and reflected from the subject.... and there is NO way to determine that without a using an IR sensitive 'meter' of some sort.
"Both LOOK ... ". Not relevant. By definiton you can NOT see IR - that is what makes it "Infra".

Do you have information about the sensitivity (@ given wavelength/s) of your IR cell?
If you do, you might be able to select a (~) standard filter/s that would enable you to match the sensitivity of your meter to that of the film you intend to use.