Can the human eye see near-infrared?

[rogerzilla]

Try this if you have a 72 (almost opaque) filter and it's a sunny day. Hold it up to your eye - don't look at the sun! - and wait for your eye to adjust.

I get a clear Wood effect on foliage, even tree leaves which appear dark green under normal light and would be rendered black by a normal red filter like a 25A. They're very bright through the 72 filter while the sky is black. If I imagine this in b/w, the grass and trees would be white, shadows would be very black, sky would be black etc.

Does the eye actually have slight IR sensitivity ("infra red" then sounds like an oxymoron) but it's normally swamped by shorter wavelengths? Or does the Wood effect work with very long wavelength red light?

Update: the first theory is correct!

http://www.rwc.uc.edu/koehler/biophys/6d.html

Apparently slight sensitivity can extend down to 1050nm, which is better than any film you can buy.

Who else can see it, though?

 

[tlitody]

The older you get the more you realise that you don't know as much as you thought you did.

 

[Roger Hicks]

Obviously, a lot depends on how you define 'near infra red' but I've found exactly the same thing. Sensitivity doesn't disappear but tapers off.

Cheers,

R.

 

[Nikkor AIS]

One of the most interesting questions I have seen asked on the rangefinder forum.

 

[Elektrojänis]

I'm not sure where but somewhere it was said that when it's dark our eyes peak sensitivity moves towards longer wavelengts.

Ah... It is said in the end of the linked article. (Interesting article I might add... Thanks!)