By Chris Lane
During the early morning hours of August 28th, we will be treated to the second lunar eclipse of the year. The first eclipse occurred on the evening of March 3rd. If you want to document this celestial event it’s not hard to do, but patience is required. The Web is littered with how-to articles, but here’s a summary of the techniques that I used in March.
The August Eclipse
The August 28th event will be visible across the entire United States, but viewers in the West will have the best show. In the Midwest the eclipse will begin at 3:20 a.m. CDT and will end at 6:23 a.m. CDT. Simply add or subtract an hour or two on either end to get the schedule for other time zones. The Moon will appear in the WSW part of the sky and will be setting in the West as dawn begins to light the sky. In the Midwest totality will still be in progress as the Moon sets. This should present some very interesting photographic opportunities. Expectations are that this event will be a bit duller and darker than the March eclipse. According to Sky & Telescope, you may see a bright yellow or even blue arc just inside the umbra’s edge. The Moon should appear very three dimensional due to this effect.
Make sure your camera has a fully charged battery. Use a tripod and a cable or remote release. Although your exposures will not be that long, since both the Moon and Earth are moving you’ll want to minimize any additional motion. Noise should not be a big issue. Be sure to turn off IS or VR as that technology can create problems when used on a tripod. Choose your focal length depending upon the type of image you want to make. If the Moon is merely a part of a larger landscape you can go wide. If you want the Moon to be the dominant feature, go as long as you can. I prefer 300mm and up. Use your lens unfiltered and with it’s lens hood. The hood will minimize dew formation and stray light.
In March I used a Canon 30D set up as follows:
•Image Quality: RAW
•Drive Mode: Single
•Review Time: 8 sec.
•Auto Power Off: Off
•Image Stabilization: Off
Don't rely on auto-focus or auto-exposure and shoot a series of bracketed test exposures using the Fred Espenak Exposure Guide.
Fred Espenak Exposure Guide
Fred Espenak, a.k.a. MrEclipse, is an astrophysicist at the Goddard Space Flight Center and is best known for his work on eclipse predictions. He has his own NASA website and in 1996 he developed a Lunar Eclipse Exposure Guide, an updated version of which is reproduced below.
How to Use the Exposure Guide
The luminosity of an eclipse is determined by using the following guidelines:
L = 0 Very dark eclipse. Moon almost invisible, especially at mid-totality.
L = 1 Dark Eclipse, gray or brownish in coloration. Details distinguishable only with difficulty.
L = 2 Deep red or rust-colored eclipse. Very dark central shadow, while outer edge of umbra is relatively bright.
L = 3 Brick-red eclipse. Umbral shadow usually has a bright or yellow rim.
L = 4 Very bright copper-red or orange eclipse. Umbral shadow has a bluish, very bright rim.
Choose a ISO and aperture, then go straight down into the second table to the subject you want to photograph. Except for Earthshine, exposure times longer than about four minutes are really not practical, since you don't have unlimited amounts of time before the event ends.
A final word
Don’t rush. The night will likely be warm and the event will be a long one. Take your time and plan on chimping and making lots of exposures.
Ctein Comments: Nice article! I'd like to add a warning about long exposures. The moon is a moving target—it moves its own diameter every two minutes. Long blur-free exposures are not possible except with a tracking mount. How long an exposure can you get away with? It depends upon how sharp you want the results to be and what focal length lens you're using. For instance, with a 300mm lens, the moon's image will span a few hundred pixels in the camera. If you want the photo to be pixel-sharp, your exposure times can't be longer than about half a second. You'll probably be quite happy with something less than that critical level of sharpness. But there are limits. Even with a "mere" 10 second exposure, the moon will move 1/12th its diameter during the exposure. Outside of extreme wide angle photos, that's not likely to be acceptable. So 1/2 second is safe (except for extreme telephoto images) while 10 seconds is not (except for extreme wide angle images). Where should you be in between? It's a matter of taste. Fortunately, you'll want to bracket heavily during totality anyway. Just know your limits and don't try more than several seconds unless you're tracking on the moon with a guide scope.