On Sat, 08 Mar 2008 14:21:59 -0800, Richard Clark wrote:

On Sat, 8 Mar 2008 10:12:04 -0800 (PST), K7ITM wrote:

Is there any limit to how low a light level I can use and still see the
pattern?

Hi Tom,

The Quantum Efficiency of the eye is between 40% and 50%. The time to
convert one photon in a visual receptor is roughly 14 femtoseconds.

I have seen no component that can match the bandwidth, dynamic range,
AND sensitivity of the eye.

Side note:

Back in the day, when I did a lot of color processing and printing, I
would spend log hours in the darkroom in total darkness.

The only light shedding items were the old Gra-Lab timers, and
luminescent tape on the dangerous corners. After several hours, the light
output from them was just about nil.

My eyes were totally adapted, full visual purple. At this time, the
luminescent tape and dials seemed to scintillate discretely, not the
typical overall glow.

I always wondered if I was possibly seeing individual photon effects.

- 73 de Mike N3LI -