Rudimentary astrophotography

Tuesday, 23 May, 2023 — photography

One great thing about living on a hill in the country is great sky visibility. Our visibility of the hill’s downslope starts to the southeast, so, at night, we get a great view of rising constellations.

Through the winter months, Orion and the Winter Triangle look fantastic. In January, with a New Moon, I can get the full Winter Triangle after it’s cleared the tree line from 8 pm onward. Heading towards Summer Solstice, the Big Dipper sits right over the yard, handle pointed towards the east southeast.

Our house isn’t in the darkest area, we can see sky glow around from Philadelphia to the south, the New York metro to the east, and the Lehigh Valley to the north and northwest. Even with the light pollution, the backyard is a fun spot to experiment with astrophotography.

I’m working with single exposure images instead of image stacking until I get more experienced with focusing, exposure, and composition to make capturing, editing, and processing an image sequence worthwhile. The good news is modern cameras, lenses, and processing software are remarkably capable of yielding stunning results. On later dSLRs and recent mirrorless interchangeable lens cameras, photographers can push ISO pretty high before really sacrificing image quality to noise.

As with other genres of photography, there’s a wide range of equipment useful for astrophotography. There’s not a lot of a equipment that’s necessary to get started. A recent interchangeable lens camera like a dSLR or mirrorless camera from any major manufacturer, a lens, and a tripod are enough to get started.

Some specifics to start with:

• An interchangeable lens camera, either a digital single lens reflex, or a mirrorless interchangeable lens camera
• A lens that:
  • Can be focused manually
  • Has a focal length somewhere between 12mm at the very wide end to 50mm at a standard viewing angle
  • Has a maximum aperture at f/4 or faster (3.5, 2.8, 2, 1.4)
• A tripod
• A way to trigger shutter release without shaking the camera
  • A wireless remote
  • A corded off-camera shutter release
  • A shutter release delay function on the camera

The limitations of the equipment you start with are worthwhile. There’s no moving star tracker here. Instead, the learning emphasis is on composition, exposure, and the part I’ve found the most challenge with, focusing. Throwing the lens into manual mode and setting the focusing distance to infinity ought to work, and yet, my results show an incorrect assumption with blurry stars. Using too high an ISO means photos get noisy and/or show banding. Too long of an exposure and the risk is motion blur from star travel. Star travel is fast enough that even at 24mm (in full-frame terms, 16mm for APC-C or 12 mm for Micro 4/3) exposure to exposure can be enough to see noticeable star movement, particularly shooting toward the equator.

There’s more info from Photography Life that concentrates on beginning Milky Way photography, but the general ideas there are valid for constellations, too.

Once I get a better sense of single-image composition and getting results I like in the backyard, I’ll be exploring night landscapes.