Lunar eclipse time lapse video and how I took it

Something I’ve always wanted to do was a time lapse video of a lunar eclipse where only the moon’s actual motion into and out of the earth’s shadow. Here I’ll show such a video and how I took it.

Here’s a video from the April 15, 2014 lunar eclipse (unfortunately clouds blocked the moon as it was leaving the earth’s shadow)

 

How I took it

First a little explanation. The problem with doing this is a lunar eclipse lasts a few hours and during that time the earth’s shadow moves to the west as the earth rotates but the moon’s orbit has it moving to the east but at a much slower rate. This means that if you just used a camera on a tripod, the eclipse would cover a wide span of the sky and the earth’s shadow moves across the moon in the same direction of the moon’s motion across the sky – here’s an example

 

The moon is moving from left to right but the earth’s shadow appears to also move from left to right making it look like the shadow is catching up to the moon. I always thought that makes it less than obvious what was going on. In order to remedy that, I attached my Canon 70D on a small telescope – an APM/TMB 80mm F/6 (480mm focal length) – mounted on my NJP equatorial mount. An equatorial mount rotates in the opposite direction of the earth’s rotation, thereby keeping the stars (and the earth’s shadow) stationary in the telescope. Another benefit of using this mount is that I can connect it to my laptop and point it at the precise location of mid eclipse.

Here’s a picof the scope and mount

NJP_TMB80

The software I use to control the mount is TheSky version 6 (not the most current version). This allows me to not only control the mount, but to plan on where the moon would be in the frame over the course of the video. The screen shot below shows the field of view with the moon. By changing the time, I can see where the moon would appear at different phases of the eclipse. This allowed me to decide which was the best telescope to use.

MoonTheSky

Once everything was planned and set up, I set the camera to aperture priority so it could try to adjust the expose length. Because the moon moves through the frame, it only got the exposure right mid eclipse and over exposing the moon for the rest of the sequence. I used an intervalometer to space the sequence of exposures and created the video using Virtualdub. Note: if you want to use Virtualdub, download the 32 bit version because many of the plugins for it do not work with the 64 bit version.

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