One of our first vexing problems was, “what settings do I use for manual exposures?” At first, we’d get a base setting from a published photo somewhere, and experiment by trial and error. Since we were just learning to use the equipment, and “trial and error” means looking at a digital camera LED, that was fine.
It took a long time for us to take a serious look at the Exposure Tables in the highly regarded Astrophotography for the Amateur, 2d edition, by Michael A. Covington. When we did, the tables were straightforward enough, for prime-focus photography. But what about filters? What would happen when we started using eyepiece projection, or afocal coupling? The extra lenses change total system magnification and f-ratio. And what if Mars were considerably closer, as it will be soon? The formulas are really intimidating; we haven’t done most of that math since high school.
We said, “Hey, we should be able to do all that in Perl!” And we did. Take a look in the Astronomy sidebar Permalinks for “Exposures – Easy” (canned scenarios), and “Exposures – Custom” (custom scenarios with bells and whistles). Enter your scenario in the HTML form, and print out the resulting photo exposure table for a happy night of viewing and photography! You’ll find notes and formulas to document and explain
what we’re doing, though if you get into this, we really recommend the Covington book!
471 total views, no views today