Saturday, February 2, 2019

Astrophotography Takes a Lot of Patience

When you see a beautiful astrophotograph, you are often looking at enormous patience: usually more than I have.  Thursday night was awesome: clear, little turbulence, and no Moon to wash things out.
The Pleiades were my first target.  I found that only with my lowest power eyepiece (85mm, or 23.5x) could I get the entire cluster in the field of view. It was very satisfying to look at, but attempts to take a picture were a bit disappointing:
1/8 second, ISO 3200, 2000mm.

I was hoping for a wider field of view; perhaps using my smaller telescopes.  Serious astrophotography often involves rather specialized telescopes that are f/2 or so.  I tried longer exposures and discovered that while the scope was tracking, I was obviously not exactly aligned to true north:
1/6 sec., ISO 3200, 2000mm.

If you look at these images in more detail:

You can see that there are two motions, one caused by drift across the sky and the other is likely from when I pressed the shutter button.  Ordinarily I use the timed delay shutter release, but I wasn't thinking far enough ahead when I left the well-illuminated area where you can actually see the buttons.

So I moved on to M42, the Orion Nebula, which is the faint fuzzy patch in Orion's sword.  Similar problems, but at least there was some of the cloud visible:



1/5 sec., ISO 51200; 2000mm.  Next time, more effort getting aligned on north first.  I had just returned from teaching American history, and I was too tired to do this properly.  I still have some disappointment.  The rule of 600 says that I should be able to  a 3 second exposure without a clock drive, but in this case, the clock drive moving me off true north might have made it worse than none at all.  This picture of M42 I did some years ago, and it came out much better, probably because of better alignment:
21.18 sec., ISO 1600, 2000mm.  The same optics were on a conventional equatorial mount that was screaming at the unreasonable load it was carrying.

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