I did a moon shot recently (on 35mm aaarrghhh!).
I used an 800mm lens (400+2x teleconverter). Any shorter and it would have been tiny. At 800 it was a decent size, but could have been larger.
The lens was set at f5.6, so thats f/11 with the converter. With 400 colour film I shot frames at 0.5 and 1 second. Both came out nicely (I haven't checked the negs as I just put the film through a local lab, and it came bacl fine).