Sunday, September 7, 2014

Lagoon Nebula and Trifid Nebula with Canon T5i on Orion Motorized EQ-1

Lagoon Nebula and Trifid Nebula with Canon T5i
Canon T5i on Orion EQ-1M, 240 subs, 46 darks, 81 bias, ISO 800, 6 sec, f/5.6, 300mm
In spite of the waxing gibbous moon (which happened to be International Observe the Moon Night) I got a good stack for the Lagoon Nebula and Trifid Nebula. I improved on my last attempt from last summer. Previously I was restricted to 1.3 sec exposures on a fixed tripod - obviously longer exposures on my motorized mount is paying off!

This stack is a total exposure time of about 24 minutes, which is by far the longest net light exposure I've ever done.  You can clearly see the nebulosity in both nebulae. I also spent about 2 hours processing this image, and learned a new and better way to stretch curves in Photoshop rather than in Deep Sky Stacker. DSS is nice to get a rough approximation, but curves in Photoshop come out a lot smoother.

I also used my subtract Gaussian Blur technique for light pollution to remove the hot spot gradient in the middle of the image. It was a quick fix, but it did the job. I tried using a star mask without success, I guess I just don't understand how that works just yet - but the subtracted blur layer does a nice job removing gradient fuzz.

Canon T5i on Orion EQ-1M
Canon T5i on Orion EQ-1M
With a 300mm lens, my DSLR on the Orion EQ-1 was pretty easy to get a BASIC alignment. I was happy that Polaris was just barely visible over the roofline from my backyard without needing to set up on the grass. I used live-view manual focus, and then loosened the thumb screws to slew all the way around to the southern sky.

I could get 6 sec exposures without star trails, which is shorter than I got the other night on Andromeda, because the stars closer to the celestial equator appear to be moving faster than stars closer to the celestial pole.

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