Eclipse of moon on Oct. 27

Owamanga wrote:

But it can only cancel out if the subject (the moon) reflects each
color evenly (ie, is white, as it more or less *is*). But if the moon
has a hue, and the flash-light reaching the moon has been red-shifted,
we are now illuminating our colored subject with a non-white light.

There are four ****s:
(1) a large redshift due to the Earth,
(2) a small blueshift due to the Moon,
(3) a reshift after reflection, and
(4) a blueshift upon arrival.
When summed, the effects cancel out, because (1) and (4) are equal but
opposite, and so are (2) and (3).

The colour of the target is another matter. But remember that even the
colour you see from Earth is wrong, because (3) and (4) above aren't
equal in magnitude.

Lets imagine for a moment that the moon is deep blue, hit it with red
light and you get a dark result. That darkness being reflected back to
the earth can't be corrected with a blue-shift, the light is simply
missing.

With a typical flash spectrum, that would require some serious redshift...

-- Lassi

Owamanga wrote:

But it can only cancel out if the subject (the moon) reflects each
color evenly (ie, is white, as it more or less *is*). But if the moon
has a hue, and the flash-light reaching the moon has been red-shifted,
we are now illuminating our colored subject with a non-white light.

There are four ****s:
(1) a large redshift due to the Earth,
(2) a small blueshift due to the Moon,
(3) a reshift after reflection, and
(4) a blueshift upon arrival.
When summed, the effects cancel out, because (1) and (4) are equal but
opposite, and so are (2) and (3).

The colour of the target is another matter. But remember that even the
colour you see from Earth is wrong, because (3) and (4) above aren't
equal in magnitude.

Lets imagine for a moment that the moon is deep blue, hit it with red
light and you get a dark result. That darkness being reflected back to
the earth can't be corrected with a blue-shift, the light is simply
missing.

With a typical flash spectrum, that would require some serious redshift...

-- Lassi

On Tue, 19 Oct 2004 23:44:52 +0100, Prometheus
wrote:

I once carefully took a non-flash photo of a group of people watching a
large bonfire at night intending to get the backs of the people in front
of me in silhouette and the faces people of the people to the side lit
by the flames; the bonfire and the faces came out well, unfortunately
just when my shutter was open some **** took a flash snap and lit the
backs I wanted to be in silhouette. When I got the film developed and
saw it I was not happy!

Really tough that everyone didn't respect your (unnanounced)
right to the moment. If you'd been paying attention, you'd have taken
another couple of shots.

Heck I tried a few shots of last months full moon, if I was staying home I'd
go for the eclipse, but not where I'll be going with my telescope, not good
there.


--


"And for the second time in four million years, the monolith awoke."
Arthur C.Clarke 2062dyssey three

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wrote in message
...
On Tue, 19 Oct 2004 23:44:52 +0100, Prometheus
wrote:

Really tough that everyone didn't respect your (unnanounced)
right to the moment. If you'd been paying attention, you'd have taken
another couple of shots.



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