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The moon and Jupiter last night

September 5, 2009

Full moon Sept 4 2009

Last night I attended my first meeting of the Pomona Valley Amateur Astronomers, who, you’ll recall, were kind enough to invite me along on their Mt Wilson trip a few weeks ago. The evening’s feature presentation was  on the Juno mission to Jupiter, which is under construction right now. Juno is slated to launch in two years and arrive at Jupiter in 2016 for a year-long observing run. Unlike the Mars rovers, which can be run until they quit, probes to the Jupiter system are deliberately crashed into Jupiter while they’re still functional. This is to avoid having a probe break down, crash land on Europa, and contaminate it with terrestrial microbes.

It was a great talk and I was feeling jovial–and Jovian–when I got home, so I hauled out my 6-inch reflector to have a look at Jupiter. The atmosphere was fairly clear and steady so I got out my camera. My method–holding the camera by hand up to the eyepiece–is called afocal projection photography by photographers and opticians, digiscoping by birders, and white trash astrophotography by me. My camera is an older model, a 4MP Nikon Coolpix 4500, but it has good optical zoom and it is a favorite for this sort of thing among birders.

If you want all the nitty-gritty, I put the camera in macro (flower) mode, manually set the exposure, zoom to the desired level, let the camera autofocus on the target, and snap away. I usually take between 50 and 100 pictures. This gives me a good sample from which to pick the one or two best shots afterward. Sometimes my hand moves, sometimes the autofocus gets squirrelly. The biggest thing, though, is that atmospheric turbulence varies moment by moment. Even on a night when the sky is roiling there may be short windows of stillness, and vice versa, so it pays to take a lot of pictures in hopes of hitting the jackpot. Many people now are using webcams, which shoot continuously, and then choosing only the sharpest images to stack and process. I haven’t ascended to that level yet.

Last night turned out to be exceptional, at least during the brief interval around midnight when I was out shooting. I got the sharpest pictures of the full moon and of Jupiter that I’ve ever taken, and the first I’ve ever gotten of Jupiter with all four Galilean moons. Click the picture below for the full size, unlabelled version (moon IDs from Stellarium). Clear skies!

Jupiter and moons Sept 4 2009 480

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5 comments

  1. So cool.


  2. I think the people using webcams are not just picking shots, but combining tiny scraps of pixels from each picture that happen to be in focus, to get a single composite image. I guess the pro astronomers are suspicious of this method because it’s too much like selection bias: sure, the picture looks good, but is it honest? For the likes of us, they’re the same thing.


  3. […] out from Jupiter: Io (by itself on the right), Europa, Ganymede, and Callisto. This is only the second time I’ve gotten Jupiter and all four kids in one shot; often one of the little bleepers is off in […]


  4. Matt, I was just reading this post from 5 years ago, and I was wondering if your technique has improved since then. I’m trying to do the same thing, but with my smartphone, and I’m finding it extremely difficult. Like with you, the autofocus messes up, the exposure isn’t right, it’s hard to keep the phone in exactly the right position (I’m using a Samsung, where the lens is in the middle of the back of the camera, not in the corner, like an iPhone). Or there’s a problem with the camera moving when I press on it to click. I’ve tried the voice command, but it takes about 5 seconds to actually take the picture, by which time I’ve moved, or it’s blurry, or what have you. It’s fairly difficult.

    Short of buying one of those brackets to hold the phone in place, any tips you can pass along after doing this for as many years as you have? Should I use an actual digital camera instead? I’ll have to dig it out from somewhere, haven’t used one in a few years.


  5. My technique hasn’t improved much since I took these shots, and my equipment has gotten markedly worse. I started out with a Nikon Coolpix 4500, which I had gotten for research purposes. It was just a happy accident that the 4500 was also one of the best digiscoping cameras ever made, and still very much worth tracking down if you can find one in good condition for a reasonable price.

    Alas, after a decade of heavy use, my 4500 bit the dust. I used a Canon S100 point-and-shoot for about a year, until I dropped it on a paleontological field trip. Now I just roll with the iPhone. It is fairly maddening to use after having all of the manual adjustments the 4500 offered. I know there are some apps that let you control shutter speed and exposure, which would probably help a lot. I just haven’t invested enough time to learn how to use them yet. I am actually getting pretty good at holding the phone in the right spot over the eyepiece–the big breakthrough there was realizing that most of the EPs I shoot through have long enough eye relief that I need to hold the camera back away from the eyepiece by 1-2 cm to get the full exit pupil (or at least more of the exit pupil, if not the whole thing) into the camera’s objective lens.

    It’s actually a terrible way to attempt digiscoping and I wouldn’t recommend it to anyone starting out–there are much easier ways to get some wins on the board. But I’ve been digiscoping for a long time, much of that time with a truly fantastic camera, so I’ve had it easy before, and I’m deriving a certain grim satisfaction from attempting it the hard way.



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