Tuesday, March 24, 2015

Fun without a telescope

Jupiter with Moons (lower left), Beehive Cluster (upper right) in Cancer
Canon EOS 7D Mark II: ISO 2000, f/4, 2 seconds, 135mm

My experiments in astrophotography sans telescope continued tonight with some success and exciting promise! Since, given clear skies Saturday night, we'll be observing Jupiter and the Beehive Cluster (M44), I gave them a try. In our light-polluted skies Jupiter was easy to find tonight in constellation Cancer but the Beehive was invisible. With the camera and a 200mm zoom telephoto mounted only on a tripod (no tracking) I tried my first exposure of the night. Bingo! There was brilliant Jove at the bottom of the frame and, on the other edge of the image in the camera's LCD panel, was that pretty open star cluster! I re-composed the shot, leaving open space where I guessed the star cluster lay, and shot bracketed exposures. Then I swapped lenses installing the 400mm telephoto on the camera body.

Jupiter is overexposed but shows Galilean Moons: Callisto, Europa, Io, and on right, Ganymede
Canon EOS 7D Mark II: ISO 2000, f/5.6, 1.6 seconds, 400mm*

I centered Jupiter in the viewfinder and bracketed exposures later seeing that I should have allowed even more than I did for Jupiter's exceptional brightness. Before tearing down for the night -- this was a very brief session conducted from the balcony of our house -- I swung the camera around and tried some exposures of the Orion Nebula (M42).

Orion Nebula is blurred (no tracking) but shows color and the nebula's cloud structure emerging from the dark.
Canon EOS 7D Mark II: ISO 2000, f/5.6, 2 seconds, 400mm*

Examining the images on the computer screen a few minutes later, I was pretty happy. And even though it shows motion blur due to the longer exposure, the Orion Nebula was showing color! Next I need to obtain a dovetail bracket so that I can mount the camera with telephoto directly on my computerized telescope mount; this summer, the camera will piggyback on the telescope and I'll expect exciting results either way. Still, I enjoy the quick, elegant setup of camera on photo tripod and I'm discovering good images are to be had from that.

* Note: The Canon 7D is a cropped-sensor camera with a multiplication factor of 1.6, so a 400mm lens reaches the equivalent focal length of 640mm. 

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