"Andy Champ" wrote in message
...
The Natural Philosopher wrote:
Thats true for dusk, but not sunset/sunrise.

Dusk is in any case a time when our own colour receptors start to pack
in: we tend to see grey only.

Even more amusing was taking time exposures by moonlight: the film itself
(pre digital) would give an overall green cast to the picture.


I recall once many years ago waking up in the night, and looking out at
the moonlit garden with the frost on the plants, getting out the tripod,
and taking a picture. When I got it back I spent about 5 minutes
wondering why the heck I'd taken a picture of the garden. All that nice
silvery effect had gone, it looked just like daylight!

Not a touch of green though. I suspect it was Agfa slide film, as I
usually used it because (a) cheaper than prints and (b) the mounts were
nicer than Kodak.

Yes, you need to be careful not to just trust the meter and expose as if it
was daylight. I've been amazed with my digital camera to take pictures at
dusk when it's quite hard to see details with the naked eye but find that a
sufficiently long exposure can result in pictures that could easily have
been taken on an overcast day during normal daylight.

Kodakchrome slide film seems to have a very mucky green cast to the shadows
in under-exposed or night-time pictures. Agfachrome or Kodak Ektachrome are
much better in that respect.

I wonder if some of the colour cast of moonlight pictures was down to the
infamous "reciprocity failure" that film is prone to in very low light,
whereby the normal rule that halving the aperture requires a doubling of
shutter speed no longer works and the three emulsions respond differently to
light. Mind you I once took some very long exposure shots (eg f11 for 2 mins
on 200 ASA) of Christmas lights and other street scenes and didn't see any
colour cast that couldn't simply be attributed to the non-tungsten street
lights.