The best time to photograph any dark sky object is during it's passing of the Zenith. Although not every object will obviously pass this point, that is the clearest point in the night sky and the atmosphere deteriorates from this point down to the horizon. The Zenith is an arbitrary point directly above the spot you are standing. The Nadir is the point directly below you. Atmosphere does indeed play a role in the quality of your images. The closer any object is to the horizon, the dirtier the air and more motion in the air mass. Even if you know the exposure, the air mass is of such poor quality it makes no sense to shoot the object near the horizon. The motion of the moon will become apparent on your 35mm film if you shoot un-guided for longer than; 50mm = 12secs with image size = 0.45mm 100mm = 6secs with image size = 0.9mm 200mm = 3secs with image size = 1.8mm 500mm = 1sec with image size = 4.5mm This isn't about film speed or reciprocity. It's about image size on any given piece of glass or format. Guiding allows longer shutter speeds obviously. The Sunny F/16 rule does not apply to lunar photography. An example is using 800 ISO rated film. Your exposure would be f/16 at: Full Moon = 1/500 Gibbous = 1/250 First Qtr = 1/125 etc. As you can see, the sunny f/16 rule never appears. This aslo has nothing to do with eclipses. Eclipses are shadow events and change rapidly as the eclipse advances. Spot metering provides the only assurance. Here are three of the leading astrophotographer's websites for those wishing to read further; Charles Vaughn at http://www.aa6g.org/astro.html who sleeps in his truck during the long nights. Jerry Lodriguss at http://www.astropix.com/INDEX.HTM A Detroit news photographer by day. And, everyone's favorite Jack Newton at http://www.jacknewton.com/ World renowned. His collaboration with Terrence Dickinson on the book "Splendors of the Universe; A Practical Guide To Photographing The Night Sky" is one of the best books on the subject. Take care, Gregory david Stempel FIREFRAMEi m a g i n g www.americanphotojournalist.com "The brave ones were shooting the enemy, the crazy ones were shooting film"
