..The lowest setting of my white LED photon is a little lower than the PALight, and my NVG Photon running on 1xCR2032 battery is lower again (I have to ramp it up slightly to use it for navigating around my house at night)...
A Covert nose NVG PF on 1xCR2032 is the ultimate in
control for experiments in dark adapted vision, IMHO.
It just now occurs to me that a Covert nose Photon Freedom in a deep red would be a very powerful experimenter's tool. The PF's UI would be
the ultimate in control for deep red, too, having multiple output levels on the low end most certainly
below human perception. The PFs and de-powered PFs are some of the few lights with dim enough output to be able to do serious experiments.
The biggest obstacle to
meaningful experiments in dark adapted vision, IMO, is often the difficulty involved in finding lights that can go
dim enough in the color(s) you want to play with.