Here's a table I cooked up for another newsgroup. The "B" value is used for guessimating your first exposure. CCDs and Web cams typically are are equivalent to 1600 ISO speed. Some typical values reported in amateur literature: Object category NELM* MPSAS (Ba) B EV Source Moon thin crescent -6.95 6.7 8 Covington2002 Moon thin crescent 10 HAIP2005 Moon wide crescent -7.75 5.9 16 Covington2002 Moon crescent 20 HAIP2005 Moon quarter phase -8.45 5.2 32 Covington2002 terminator objs Moon quarter 40 HAIP2005 Moon gibbous -9.25 4.4 70 Covington2002 Moon gibbous 80 HAIP2005 Moon full -10.25 3.4 180 Covington2002 Moon full 200 HAIP2005 Moon earthshine -0.20 13.5 0.016 Covington2002 Moon earthshine 0.01 HAIP2005 Moon partially -8.95 4.7 50 Covington2002 eclipsed, expose bright side Moon partially -3.16 10.5 0.25 Covington2002 eclipsed, expose umbra and penumbra Moon relatively -1.48 12.2 0.05 Covington2002 light total eclipse Moon relatively 1.06 14.8 0.005 Covington2002 dark total eclipse Notes: * - equivalent MPSAS and Ba computed per this author. Accuracy needs to be confirmed by more experienced astrophotographers \ Ba is Magnitudes per square arc second B is in candelas per sq foot - used in exposure computations Sources: Berry, R & Burnell, J. 2005. 2d. Handbook of Astronomical Processing. (HAIP) at p. 122. Willman-Bell. http://www.willbell.com/ Covington, M. 2ed. 2002. Appendix C. In Astrophotography for the Amateur. Cambridge. ISBN 0-521-62740-0 http://www.covingtoninnovations.com/ Rogers, Mike. 2006. Implementation of Covington's Exposure Calculator. (Web applet)http://www.rphotoz.com/astrophoto/expcalcs.html Covington, M. 2005. Exposure Calculator. (Freeware - software)http://www.covingtoninnovations.com/astro/astrosoft.html Starzonia. 2005. Exposure Calculator. (Web applet) http://www.starizona.com/ccd/calc_ideal.htm NASA/JPL Ephemeris Generator (Computes current apparent brightness of planets including Moon) http://ssd.jpl.nasa.gov/cgi-bin/eph __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com