On Wed, 25 Dec 2002 09:12:28 GMT, AC/DCdude17
> Our scotopic vision(the mode our eyes are in at very low light
>level) is an amazing thing. After you lay in your bed for good half an
>hour or so, the light shining through the blind from street light or
>whatever is often enough to let us see monochrome image of your
>furnitures and if you move your head around, you can see the next
>furniture instantly. Close your eyes. Open them. You can see the
>image almost instantly and if we were to convert that into ISO
>equivalent, I think it will come out VERY high.
>
> I did an experiment with a film and I can tell you that even so
>called fast film doesn't perform anywhere near as well as our eyes.
>
>Lens: Pentax 50mm F2.0
>Aperture: F2.0
>Film: Fuji Superia X-TRA ISO 800
>
>Exposure durations and result:
>
>2s nothing, 4s nothing, 8s nothing, 15sec nothing, 30 sec nothing, 1min
>very slightly exposed, resolution is still much poorer than what I can
>see.
>
>All the light I had was a faint glow of green LEDs from an alarm clock
>at the other end of room and a bit of high pressure sodium light peeking
>through the blind.
>
>Even 800 speed film at F2.0 required a good minute to get any image, so
>even with 3200spd film and F1.4 lens, it will theoretically take good
>20seconds to get same density.
>
>Is it possible to capture what we see in the dark on film within the
>timeframe required to let our eyes see it strictly in available light
>mode?(no more than a sec I'd say)
Well, if we go to electronic imaging, even some
consumer-grade video cameras do a fair job of
shooting things in light levels we cannot see in
without the period of adjustment... (the Sony
VX2000 is one, used with the lens at widest
zoom setting, aperture wide-open, gain at +18db,
and shutter speed at 1/4 second), or, if "cheating"
is acceptable, all current Sony 1-CCD video cameras
will shoot in infrared mode, using a built-in IR
light source - and give a useable video image of
things we cannot see at all...;-) Reminds me of
the days when I could see the Tri-X film I was
loading onto reels for processing - yet the
processed film showed no fogging from the
light exposure during loading...;-)