Don't be confused by the fact that it is night-time. When you shoot the moon for detail, regardless of how big it is in frame, expose pretty much as you would for any normal daylight (i.e. full sun) scene, eg. 1/125 @ f11 for 100ISO, or thereabouts. Relatively speaking, the moon is no further away from its light source (the sun) than the earth is. So, therefore, it is a normal daylight scene, as lit by full sun. When you think about it that way, it makes sense. This is completely different to shooting a scene here on terra firma as lit by moonlight. This shot was taken with a borrowed Nikkor 300mm f2.8 with a 2x converter, hand-held, just standing on the street in the city. (Another valuable mnemonic - if you are using a 300mm lens, use 1/300th sec shutter speed or faster for a hand-held image without camera shake. For a 1000mm lens, use 1/1000th shutter speed, etc.)