Total Lunar Eclipse
Monday 28 September 2015
We saw a partial solar eclipse earlier this year in Dursley - and tonight we saw a total lunar eclipse. However it did involve a 3am alarm for us! People in America enjoyed the show in the evening, but it was worth getting up for. The skies stayed clear and during totality the moon went a beautiful deep blood red. A true spectacle of nature.
The media was making a big deal about this not happening again until 2033, as the moon was at its closest approach tonight and therefore appeared larger in the sky. But there will plenty of total lunar eclipses to enjoy before then - the next visible in the UK is on 21st January 2019. The moon will appear slightly smaller, but I doubt I'll be able to tell. I've seen a total lunar eclipse before, but this is the first time I've attempted to photograph one. I'm pleased with how it came out, so I've written some tips below.
Moonrise, the evening before the total eclipse
Total eclipse, the moon has gone a blood red colour
Photography tips for total lunar eclipses
The moon is small, dim during totality and moves surprisingly fast, which makes it hard to take a good photo. Let's tackle each of these problems:
- Small: You'll want the longest (and fastest) lens you have. Here I used a 300mm lens on a Nikon D7200 (DX sensor), so equivalent in view to 450mm on full frame. Then I cropped the image down significantly, so a longer lens still would be a plus. In fact you need a lens with a focal length of about 2000mm (full frame equivalent) to fill the image with the moon. Alternatively, if the moon is near the horizon, it's possible to include something in the foreground such as a building and use a shorter lens.
- Dim: I opened the aperture to the maximum possible value (f/4 in my case) to gather as much light as possible. This makes focusing more critical, which I did manually zoomed in on liveview - it's hard as the moon is so dark. My suggestion would be to try focusing several times, taking photos each time - some will be better than others. For the totality image, the ISO was set very high to 6400 and the shutter to 1 second. With such a long shutter speed, the camera was tripod mounted and I used a remote release to get avoid vibrations from pressing the shutter button.
- Moves fast: To reduce image noise, it would be preferable to use a longer shutter speed and reduce the ISO. But alas the moon and stars are moving faster than you might think and with a long lens (and fixed tripod) this leads to visible motion blur. A rough rule of thumb "the 600 rule", is to divide 600 by your focal length in mm (full frame). This gives you the longest exposure that won't show (too much) movement. So for my setup, with cropping 1 second was about the longest I could get away with. It's worth experimenting with longer and shorter speeds though - I certainly found 4 seconds gave very noticeable trails, whereas 1 second was a good balance between exposure and movement, with 0.5 second was a bit too dim. The ideal solution is to use a telescope that tracks the moon, allowing a longer exposure. I don't have one of those, so it's fun getting the best out of what you have.
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