> The f11 rule for the moon only works when I have a lens on the > camera. I have the telescope mounted directly to the camera with > no lens in between . . . so no aperture.
Well, there still is an aperture (or a "lens speed") present. The telescope must still have a rated speed (in f-stops), just like a photo lens. So, you can still increase or decrease the shutter speed to compensate for the difference in lens speed (from f/11) that your telescope exhibits. For example, if I were to use 100 ASA film with an f/11 scope, and if I were following the "moony-11 rule", I'd be shooting at 1/125 (closest to 1/100 or 1/ASA). However, since my little 500mm Schmidt-Newtonian has a speed of f/5.5, which is approximately 2 stops faster than f/11, I would cut the shutter speed to 1/500, which is two stops quicker than 1/125. Actually, the "moony-11 rule" is primarily for full moons, isn't it? And, tonight is basically a first-quarter moon, which is not as bright, overall, and so which (I think) better follows a "moony-8 rule". So, I would maybe shoot (in the above example) at 1/500 (by the "moony-11 rule"), but probably also shoot at 1/250 (and probably also at 1/125), just in case 1/500 is a little too underexposed. Fred - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
