Astrophotography

Taking pictures of the sky!

See Cafuego’s page on software for osx.

See also the Mac Observatory site.

I use the following software:

• AstroDSLR for capturing from my DSLR.
• Nebulosity for stacking images.

Theory and Books

The standard recommended reading is The Deep-sky Imaging Primer.

• A bunch of other useful links for beginners. Though, the whole cloudy nights forum is super useful.
• Other useful threads for beginning imaging on cloudy nights
• Jerry Lodriguss’s astrophotography techniques

Finding a site

Find a local dark sky site. In LA, I like Joshua Tree National Park. However, being able to easily access far-away dark sky sites is one of my primary reasons for learning to fly.

Equipment

You can get away at a bare minimum with just a camera and a tripod. My equipment checklist is:

• Camera
• 50 mm lens, because wide field shots are fun.
• Telescope¹
  • Telescope camera mount
    • (barlow lens, T-ring, etc.)
  • Bahtinov mask.
• Equatorial Mount
  • Motors for said mount
  • Batteries for the motors
• Computer (Strictly speaking, this isn’t necessary - my camera can be set to take a series of photos at once)
  • USB-A to Mini-USB-A (to talk to camera).
• RED flashlight - white will ruin your night sight. You also want low-lumen, for the same reason.
• Water
• Coffee
• Snacks
• Camping chair
• Sleeping pad/bag (even if you plan to stay up all night, bring these).
• Pillow
• Paper and Pen.
• A book or something else to do while the computer does all the work.

Be sure to set the computer to “night shift” mode² before it’s dark, as red as possible.

Go there, set up camp. Preferably be set up before dark.

Jerry’s list of beginner equipment for astrophotography, which is a potential source for expansion.

Actually Taking Photos

Regardless of how you use it, be sure to write down what you’re taking a photo of when you do it. Even if you know what the constellation/body you’re photographing is anyway.

Also, for stacking³ reasons, the more photos you take, the better it is, but it does have diminishing returns⁴.

Using a computer

Use AstroDSLR from computer to control the camera. Keep the camera in bulb mode to allow the software to control exposure time. Otherwise follow these instructions.

Make a different folder for each different set of photos you take.

Drift measurement with AstroDSLR

Copied from their website:

For polar alignment by the drift method or for the validation of the guiding you can use drift measurement helper panel.

The scale of the graph is adjusted automatically. Blue curve represents drift in X and red curve in Y direction. Blue value in lower left corner is drift per image in X direction and red value in lower right corner is drift per image in Y direction.

To use the panel for polar alignment, rotate camera (to align RA/Dec axes along X/Y directions), start preview in endless loop, select accordingly bright star and use drift method.

Please note, that the graph is cleared every time you select the star in the preview image.

Without a computer

Put the camera in manual mode, and have it set to average.

Star Trails

Sometimes you’re going for that really cool effect, othertimes you’re not.

Here’s an article from Jerry Lodriguss on how to deal with star trails.

PostProcessing

Nebulosity doesn’t read the color information from your raw files. Convert them to jpeg, because that’s still better than grayscale images.

for i in *.cr2; do sips -s format jpeg "$i" --out "${i%.*}.jpg"; done

From Nebulosity, open batch -> align and combine images. Select “Translation + Rotation + Scale”, click “OK”, and select the images to stack. Now, select the same star in each photograph as it prompts you. You’re going to go through the sets 3 times (so that it can correct for translation/rotation/scale). Now, do some manual editing, and save the end result.

Post to instagram⁵ or whatever. Use it as your new desktop background.

Last updated: 2020-01-10 11:49:17 -0800