On Apr 23, 10:09 am, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:

You overexposure by a certain amount because the moon is NOT a 16%
greycard.  You want it to look white while still retaining detail.
Additionally, shots of the Moon underexposed sometimes show noise
which can be avoided with a correct exposure.

Here's one of my Moon shots, let see yours:

http://www.pbase.com/andersonrm/image/65063908

(Alan, I bet you know most of this; I'm just trying to write
up a general explanation for everyone.)

The surface brightness of the moon does vary with phase.  The
areas close to the terminator are darker, thus lower in surface
brightness.  This is a cosine of the solar altitude effect.
As the sun gets closer to the horizon, the photons per square
meter per second decreases on the moon just like on the
earth (and all other planets too).  The crescent moon, e.g.
the one in the image in this thread has most sunlight incident at
a low angle, so the surface brightness is low, and decreasing
closer to the terminator.

As we get closer to full moon, the sun will be illuminating the sun from
behind us as we look at the moon.  In this case the cosine incidence
effect is compensated by our view as we look toward the
terminator (which is at the edge of the lunar disk) so we see more area
per pixel (or square angular area) near the edge of the moon.
The increase in surface area per pixel cancels the decrease in
photons per square meter so the moon's surface brightness does
not change over the disk as it does at other phases.

Then at very close to full moon, the micro shadows cast by grains
in the lunar soil decrease from this perspective causing the
full moon to appear even brighter.
The is called the opposition surge (not to be confused with the
other "surge" going on right now) or opposition effect.
This effect can also be seen with soils on Earth when you see a halo
around the shadow cast by your head.  Another factor contributing to
the opposition effect is constructive interference of light making the
brightness even higher (this was controversial a decade or so ago but has
now been proven so all the research scientists in this area pretty much
agree).

The moon has a reflectance lower than the average reflectance of the Earth,
so the average exposure is more like sunny f/11 rule, but when there is low solar
incidence angle, exposures become longer (when the moon is a crescent),
and shorter near full moon when the opposition surge is significant.

Then guess when happens when the moon is within about 2 degrees of
full moon?  Is it bright due to the opposition surge?
No, it becomes very dark!
It's an eclipse!  ;-)

Roger

The above statement is incorrect.

First, at a "slim sliver" you are only seeing the terminator portion
which is really twilight. At a larger phase, the round side is much
brighter. When full, the entire moon is lit like high noon.

Also, exposure not only depends on the phase but how high in the sky the
moon is. When low, you are looking through a lot more atmosphere.

Getting back to the original post, I believe the exposure was correct.
Mr. Flintstone wanted to capture the "old moon in the new moon's arms"
and overexposing the sliver was the only way to do that.

Here is a moon photo I just took tonight:

<http://www.mhmyers.com/d80/DSCN3780w.jpg>

And here is a page I made about photographing the moon:

<http://www.mhmyers.com/moon.tn.html>