Astrophotography of the Moon

This is just a quick post to show the method and results for my imaging of the Moon last Saturday night (10/19/2013). My intention was to image M31 after the Moon set after midnight but I decided to save that for another night and concentrate on the Moon.

Equipment Used to Capture the Moon Images

  • Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
  • Celestron CGEM Mount
  • Canon XSi (450D) DSLR with T-ring / T-adapter
  • Canon’s EOS Utility
  • Bahtinov Focusing Mask

Basic Method to Capture the Moon Images

  1. First was the CGEM mount setup. I pointed the CGEM at Polaris by eyeballing it then centering Polaris through the polar axis hole in the mount (where the polar finderscope goes). This is close enough for imaging the Moon since the exposures are a fraction of a second. I also leveled the mount with the bubble level built into the CGEM.
  2. Next I attached my Canon XSi just long enough to balance the mount on both the RA and DEC axis. I wanted to make sure the scope was balanced when I started imaging later.
  3. After balance was achieved, I removed the camera and inserted my diagonal and illuminated reticule eyepiece and did a 2-star alignment so I could use goto functionality.
  4. Once the star alignment routine was complete, I used the CGEM hand controller to slew to the star Vega. I stopped here first so I could attach the XSi and use my Bahtinov Focusing Mask to achieve the sharpest focus possible with the camera. The Canon EOS utility that came with my XSi was very useful here. I snapped several exposures in bulb mode (each at approximately 12 seconds at ISO 800) through the virtual interface on my laptop. With each exposure, I adjusted the focus on the ED80 until the middle spike (from the Bahtinov focusing mask) was exactly in the middle of the two outer spikes. Dalton SkyGazer has a nice tutorial on using the Bahtinov focusing mask.
  5. Once focus was achieved on Vega, I slewed the telescope to the Moon.
  6. The Moon is bright enough that it’s very easy to center it through the XSi’s viewfinder. I just used the CGEM hand controller to make fine adjustments to the position of the Moon within the viewfinder.
  7. When I got the moon centered, it was time to take some exposures. I set the XSi to Manual mode (with the dial on the camera) then changed the ISO to 100 and shutter speed to 1/200th using the EOS utility. I snapped a test photo to see how it looked. The result was satisfactory so I snapped several more images using the EOS utility.

Processing the Photos of the Moon

I tried different ways of processing the photos but settled on stacking a few frames in Registax. I found out that Registax 5.0 will allow you to stack the large RAW files that the XSi produces. After stacking, I made some minor adjustments to the levels, contrast, and color balance in Photoshop. Then I sharpened the imaged slightly with Photoshop’s unsharp mask tool.  I still have much to learn when it comes to the processing the Moon! In fact, I sent a one of the RAW frames to my good friend Martin Cohen (who also writes for AstroPhotography Tonight) to apply his magic to my photo. The result was impressive! Below is the result of my processing and Martin’s.

Moon Astrophotography 10-12-2013-Ray Shore Moon Astrophotography
The Results of My Processing The Results of Martin’s Processing

This was the basic process I used for astrophotography of the Moon last weekend. I didn’t go into too much detail here so if you have any questions, feel free to leave a comment below. We hope to have a more detailed tutorial for imaging the Moon and processing techniques in the near future so stay tuned!

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