Photographing stars

Capturing the night sky with a dig­i­tal cam­era is a dichoto­my of lim­its and capa­bil­i­ties.

So much more is revealed when you use a cam­era than with the eye, because a long expo­sure allows you to col­lect a lot more light. It’s an entire world we don’t get to see oth­er­wise. The prob­lem becomes the fact that the stars begin to blur as the Earth rotates (although the effect is some­times nice).

10 minute star trails

This was a 10 minute expo­sure at 16mm, f/4, ISO 100.

Since most Canon SLRs sup­port a long expo­sure noise reduc­tion fea­ture (which clos­es the shut­ter, takes a sec­ond expo­sure, and dig­i­tal­ly removes the remain­ing noise from the orig­i­nal), expo­sures with this fea­ture actu­al­ly take twice as long. I can’t imag­ine doing this kind of stuff back in the days of film cam­eras, with­out any kind of imme­di­ate feed­back.

The faint glow on the bot­tom right is light pol­lu­tion com­ing from Ottawa.

Looking at pic­tures of stars with­out con­text is bor­ing. I was nev­er inter­est­ed in plain star maps because they’re so abstract com­pared to neb­u­las and galaxy shots. I did­n’t under­stand what I was look­ing at, and I could­n’t pos­si­bly appre­ci­ate what I was see­ing.

Messier 13

Messier 13 — 6 sec­onds @ f/2.8, 100mm, ISO 3200.

Rated as a Class V glob­u­lar clus­ter, which is right in the mid­dle of the Harlow Shapley scale, and the most spec­tac­u­lar type because it’s the best com­pro­mise between rich­ness (low­er on the scale) and resolv­abil­i­ty (high­er on the scale).

Take this pho­to of M13 for exam­ple. M13 is a Messier object, which is a cat­a­log of astro­nom­i­cal objects Charles Messier doc­u­ment­ed to ignore because they resem­bled comets1, but did­n’t fol­low tra­di­tion­al comet’s paths.

M13 is in the Herculeus con­stel­la­tion. I could­n’t see it but I knew where it was, so I took this shot and zoomed in. On my screen was one fuzzy dot in the mid­dle of a bunch of sharp dots.

This fuzzy dot is actu­al­ly a huge glob­u­lar clus­ter, con­tain­ing sev­er­al hun­dred thou­sand stars. When I saw it through some­one else’s (much big­ger and more expen­sive) tele­scope, I could see a dif­fuse haze of white, and resolve dozens of indi­vid­ual stars around it. It was beau­ti­ful, like a series of dia­monds set on a glow­ing jew­el, and there’s no way I would appre­ci­ate a shot of Hercules if I did­n’t see M13 like this.

Due to the large con­cen­tra­tion of stars in this glob­u­lar clus­ter (and pro­por­tion­al­ly greater pos­si­bil­i­ty of extra-ter­res­tri­al life), it was select­ed as the place to send the first mes­sage into out­er space.

It’s all these lit­tle details that make space so fas­ci­nat­ing. These are celes­tial objects of such vast and incom­pre­hen­si­ble sizes, but at the same time, they’re bare­ly seen by the naked eye on a night with even the best of con­di­tions.

  1. Messier was known as a comet hunter. []


  1. I was nev­er inter­est­ed in plain star maps because they’re so abstract com­pared to neb­u­las and galaxy shots.
    Hmm, I’ve always liked star charts! Star wheels are com­pli­cat­ed (and not because I still don’t know how to use them, no way…), but star charts are con­crete… no need to wor­ry about the stars mov­ing out of your line of sight every few min­utes if you’re doing work. But yeah, noth­ing com­pares to see­ing it with the naked eye/a tele­scope.

    (Hopefully you get to see Saturn through a tele­scope some­time— it real­ly is spec­tac­u­lar!)

  2. Wow awe­some! I’ve been want­i­ng to get into astropho­tog­ra­phy. I wish there was a way for our dig­i­tal cam­eras to do those 4 hour expo­sures though to get the full cir­cle.

    • Actually, there is a way for our cam­eras to do that; you just need an inter­val­ome­ter. Canon makes one for our cam­eras, but it’s pret­ty expen­sive (I think around $150). I bought a cheap knock-off for $45 off ebay and it’s work great. They can keep the shut­ter open for up to 99 hours!

  3. Do you realise how much this looks like the cov­er of the new Band of Horses album? Speaking of which, have you heard it?

    • I did see that cov­er recent­ly, but did­n’t think any­thing of it. I’m not real­ly in the mood for that kind of sound right now, but I imag­ine I’ll give it a lis­ten even­tu­al­ly.

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