Astro Arash

M101 – Pinwheel Galaxy

I got a new lens – an old Canon 200mm f/2.8! I was in particular excited for the large aperture and better optics. A 25 second exposure at f/2.8 is roughly equivalent to a 2 minute exposure at f/6.3 (which is what I was doing on my kit lens), all things else being equal. Additionally, this prime lens comes with significantly better optics than any kit zoom lens. Obviously not as sharp as a dedicated telescope, especially when wide open, but a significant improvement nonetheless. For roughly a third of the cost of some of the popular widefield refractors out there, I’m pretty happy with this lens thus far.

Of course, the golden rule of astronomy says that as soon as you get any new equipment, the clouds will promptly roll in. I had basically two weeks of almost constant clouds (at night, several sunny days though). I got a peek or two through some intermittent clouds to test things out, but that only made me more eager for a clear night.

I finally got a night without clouds and it did not disappoint. I went after M101, the Pinwheel Galaxy. Combined with some earlier data, I got about 4.5 hours worth of integrated exposure over a few nights in May. I was pretty happy with the result, and I’m excited to keep using this lens!

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