Moon exposure...not what you might think!!!

[GPS]

Your attitude sucks and you're technically incorrect. While it's true that the absolute (sun) light reflected by the moon does change with its phase, it doesn't matter because you're trying to make your exposure to give the visible (lit) part of the moon a certain value (say, zone 8). Whether it's at a quarter full, half full or full, you presumable still want the bright part to register the same value on your film (or sensor). That's why a "rule" like the one at which you snicker will work equally well for the moon at any phase. You're confusing a light source (the moon, since the sun, although it is the true source of the illumination, is behind the earth at this point) with reflected light. Try some low-light and night photography, you might learn something.

Somehow you forgot the change in Moon's reflectivity - from 2 (even less, in fact) to 15%. I know, for some people "it doesn't matter"...

[paul08]

While I know responding to you with your great internet-based knowledge is futile, I suggest you re-read my post. I wrote (in part):

"While it's true that the absolute (sun) light reflected by the moon does change with its phase, it doesn't matter because you're trying to make your exposure to give the visible (lit) part of the moon a certain value"

The "change" I was referring to accounts for Keith Cooley's exposure table differences. That doesn't alter the fact that I can photograph the 1/2 moon on a clear night at a given exposure combination (say 1/60" @ f/11 w/ISO 100 film) and under the same atmospheric conditions two weeks later get a great (and equally "accurate" - to the eye) exposure of the full moon with the same aperature/shutter speed. Try it yourself. It's amazing what you might discover through practice, in addition to reading the internet.

[GPS]

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The "change" I was referring to accounts for Keith Cooley's exposure table differences. That doesn't alter the fact that I can photograph the 1/2 moon on a clear night at a given exposure combination (say 1/60" @ f/11 w/ISO 100 film) and under the same atmospheric conditions two weeks later get a great (and equally "accurate" - to the eye) exposure of the full moon with the same aperature/shutter speed.
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I wonder why the agreement on the different exposure time according to the Moon's phases when YOU can take pictures of it with the same exposure all the time...
And why is there a table with exposure differences according to Moon's phases...
Some people just take it all with the same exposure - it doesn't matter You too should google before you give away your wisdom...
By the way, I'm a contributing photographer also in a scientific photo agency with my specialization for atmospheric, meteorological and astronomic photography... Don't worry, it "doesn't matter".

[GPS]

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Gee if the moon isn't full, I guess I should open up... That's too difficult for some people I guess.

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There is only 2 stops difference in exposure between exposing for a full moon and exposing for a quarter moon (the difference is mostly because the postion of the sun relative to the moon and Earth).
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Just add one stop for 1/2 moon. Add another stop for 1/4 moon. Interpolate for anything in between.
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Do the same with the moon: run the meter over it while observing the readings; depending on your taste, put the exposure 1 to 2.5 stops up.
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That doesn't alter the fact that I can photograph the 1/2 moon on a clear night at a given exposure combination (say 1/60" @ f/11 w/ISO 100 film) and under the same atmospheric conditions two weeks later get a great (and equally "accurate" - to the eye) exposure of the full moon with the same aperature/shutter speed.
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The Moon exposure... not what you might think!!! Indeed...

[Brian Stein]

In photographing the moon, when low on the horizon, how long a shutter speed can be used before the motion of the moon becomes evident.

DAB

To try and get a back of the envelope upper bound exposure time assume
1. if something on the film moves less than the circle of confusion it is probably not detectable,
2. that one uses a lens of focal length f,
3. and as mentioned the moon apparently moves about 1' of arc every 4seconds because of the earths rotation.

This angular movement will roughly translate on film to f tan \theta, so if f tan \theta <CoC we're ok (roughly!!).

For me using a 300mm lens on 5x7 where Coc (judged by d/1500) is about 0.15mm implies \theta is about 0.02 degrees or fairly close to 1' of arc. In *theory* I can get away with 4" exposure. Of course Im going to have an eeny weeny little moon image........ and maybe some star trails too......(for a 300m lens probably will get trails if exp>2-3' http://home.hiwaay.net/~krcool/Astro/moon/howtophoto/)

For one of the posters telescopes on 35mm film (CoC ~0.029mm) \theta is going to be more like 1/25' arc with an exposure max *in theory* of 1/5" before movement is seen (again start trails at about this time point but a much bigger image on film).

Thus for an astronomer type wanting a longer exposure to get enough light then you need to move the lens along with the earths rotation.....

Hope this answers some of your question