This calculator provides provides an estimated shutter speed for lunar eclipse photography based on the selected ISO, aperture, angle of elevation of the Moon, altitude of the observer, and the nature of the eclipse. A similar calculator is available for normal photography of the Moon.
To display the suggested exposure for a lunar eclipse, select the type of event, the film or sensor speed (ISO), and the lens aperture (f/number). The altitude of the Moon and the elevation of the observer have a measurable influence on the exposure time, as do sky conditions. The suggested exposure will be computed and displayed every time a parameter is changed.
The exposures are given only as a guide. They help when choosing an appropriate film (or sensor speed) for the equipment in use and the particular event being photographed. An automatic sequence of exposures can consequently be set up in advance of the event if required. However, on the day of an eclipse, be sure to bracket exposures by one or more stops in both directions to take account of variations in the actual sky conditions and other phenomena. If the sky is not clear, or conditions are hazy, lengthen exposures.
Calculator by kind permission of Xavier M. Jubier