More Looniness

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The moon setting at twilight through a gap in the accelerator tower structure. A 1/8 sec hand-held exposure. 2005:04:11 18:32:49
The moon setting, shortly after dark has fallen. Tripod-stabilized 1/2 sec exposure taken through (not so much stabilized as well-balanced) binoculars. I've pumped up the levels to emphasize the degree to which Earthshine was illuminating the Moon's night side. 2005:04:11 19:08:29

Yes, more pictures of the moon. It's just an absurdly attractive astronomical target for those of us with very minimal tools. As the moon was new just last Friday (hence the eclipse -- did any of you see it?), we've got a thin crescent now, setting in the much-discussed prongsy configuration. The earlier shot, I took as I was leaving the physics building at twilight and noticed the Moon peaking out through one of the gaps in the accelerator structure. It took me a few attempts to get a good shot, since I was just holding the camera.

Later that night I set up on the roof of my dorm (actually to show one of my friends an Iridium flash), which has a decent view of the horizon. After a considerable bit of fiddling, I found a way to get the camera stably pointed through my binoculars -- a tricky proposition, since I only have the one tripod, and the tripod I have doesn't easily allow pointing the binoculars upwards.

Below, the full-resolution version of this shot. I think I'm getting better at this.

The same shot as above, but not scaled down and with the white level toned down slightly to bring out surface detail. Consider this a proof-of-concept for digital camera+binoculars astrophotography; looks like I can do roughly 1° FOV, low-elevation fields now without too much trouble.

Notice the prominent blue band just below the Moon's illuminated limb in the above shot. This is clearly differential refraction at work, but I haven't yet decided exactly where it is taking place. This field is close to the horizon, so the light does pass through a rather considerable air mass. On the other hand, it could just as well be in the binoculars or the camera, too (although I think other high-contrast shots of things like the Moon rule out chromatic abberation in the camera). I could find out by taking a similar picture of the Moon when it is higher in the sky, later this month. But to do that, I'll have to work out the attendant mounting issues first.

1 Comment

One of the great aggravations of wearing glasses is the differential refraction that occurs when I look at something at an angle through the lenses. Perhaps your camera was not precisely lined up with the binocular lenses?

Also, the photos are really very pretty. I don't get out much anymore, and so haven't actually seen the moon in quite some time. It's nice to be reminded of something so lovely.

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This page contains a single entry by Milligan published on April 13, 2005 11:35 AM.

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