Timelapse and Lens Testing

A view to the southwest includes the Milky Way, a target for one of my tests, behind incoming clouds lit by city-glow.  The observatory has visitors whose cars illuminate its shell.,

A mostly clear night, and a new lens to try out!  A lens I was hoping to use to capture wide-angle views of the Milky Way, and of northern lights, should I ever be in a position to do so.

I headed to Baylor Park, which is the home of Eagle Lake Observatory, operated by my astronomy club.  I wasn’t there to use its facilities (though others were).  I just wanted a clear view of the sky outside the city, somewhere I could practice techniques for making timelapse sequences, preferably alone, where I could make mistakes without an audience.

I set up my tripods and cameras in the open areas of the park just outside the observatory and started my various tests and experiments.  I mostly wanted to find out what exposures worked with my new fast lens to detect the Milky Way.  I also wanted to see how sharp it was when operated at full aperture– did the stars stay sharp to the edge?  And what was the image noise for the frame rate I needed?  I could answer these questions with a few test sequences.

But night sky timelapses take a long time.  At 10 seconds per frame, and a playback rate of 30 frames per second, it takes almost an hour to get a 10 second movie.  So I prepared to spend the evening monitoring the progress of my cameras.  I know this routine; I’ve done it before.  There is a lot of preparation and setup and anxiety prior to starting, but once the camera is clicking along, there is not much to do, except worry about the battery level, or that I got one of the settings wrong and the whole sequence is not what I intended.  

The evening did not go as planned.  I discovered that the park is under a main approach path for MSP airport.  The planes seem innocuous enough as they cruise by, but in timelapse they appear as invading missiles!

And somehow, even though the solar wind activity was low that evening, a local news outlet had announced that there was a possibility for northern lights.  This resulted in dozens of vehicles arriving, with their headlights sweeping across my cameras, and with families and groups of sky watchers spilling out of them.  The place was a nighttime party of flashlight-wielding enthusiasts, eagerly looking for any sign of aurora.

They were disappointed by the northern light no-show, but a night of stargazing is hardly ever awful (as in the cartoon caption “Damn, I read an unassigned poem”).  The sky was partly cloudy, but the weather was mild for December, and the open areas offered beautiful views of planets, constellations, and the Milky Way.

I have learned not to shut down when things don’t go according to plan.  My cameras recorded the unexpected activity along with my night sky targets.  After all, this was only a test and practice shots, I had no illusions of acquiring award-winning footage.

In the end, I mostly got the answers to my questions.  The new lens was remarkably sharp; it successfully detected the Milky Way, even in these moderately light polluted skies, at a frame rate that yields pleasing movement across the scene.  I learned that this rate was not right for clouds– they moved too fast.  Slowing the playback rate gave the right cloud motion, but jerky.  And the slower playback rate made the star motions too slow; the dramatic impact of timelapse was lost. 

Nothing remarkable, other than the interference of enthusiastic aurora seekers. You can see the original at full size at: https://vimeo.com/521655954

The evening at Baylor is summarized in the short compilation I made, including the comical motions of various groups of star gazers.   Although I learned enough, I will be happy to continue my tests on another night. For me it is all poetry, assigned or not.

If you are interested in my occasional contributions to Thor’s Life-Notes, I invite you to follow along.

2 thoughts on “Timelapse and Lens Testing

  1. The evening described was last December 9, 2020. Covid rules were in place, and we had our masks and social distance rules in place! I hope that in this next year public star parties will resume as before. I recall many evenings of sharing the view through my telescope to interested visitors.


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