I spent my Christmas holiday working on learning how to use the astrophotography processing tool PixInsight. There’s an enormous amount to learn, and I’m looking forward to learning more. But I am happy with the results of my first project – the Andromeda Galaxy.
For comparison, here is a single 3 minute shot with only basic processing. I think the processing is worth it!
Camera geek info:
Canon EOS 60D in manual mode, 179 second exposure, ISO 1600, custom white balance 3500K
Williams Optics Zenith Star 73 III APO telescope
Williams Optics Flat 73A
iOptron CEM40
Dell City, Texas Bortle 2-3 dark skies
Processing geek info:
PixInsight
18 3 minute lights
10 3 minute darks
50 bias frames
No flats
ImageIntegration Darks to make Master Dark
ImageIntegration and Superbias flats to make Master Flat
After my previous 3 minute Andromeda Galaxy comparison, I decided I needed to get a light pollution filter to get better pictures from my driveway given our Bortle 7 skies. I picked up a SkyTech 2” LPRO-MAX CCD Filter and the image above is the result.
For comparison, here is a picture using the same settings and location with no filter.
And here is a picture using the same settings from Bortle 2 skies.
All these pictures used the same equipment and settings. For the purposes of this comparison, I did not do any processing. I think the filter was worth it. Dark skies are definitely worth it!
Camera geek info:
Canon EOS 60D in manual mode, 179 second exposure, ISO 1600, custom white balance 3500K
Williams Optics Zenith Star 73 III APO telescope
Williams Optics Flat 73A
iOptron CEM40
I also experimented with settings to use from my driveway. Results are in the table below. Lowering the exposure length and ISO cut down on the sky noise. I’ll have to see what I can do with the 1 minute ISO 400 images in PixInsight.
Site
Bortle
Filter
Exposure Length
ISO
Result
Dell City, Texas
2 – 3
None
3 minutes
1600
Gorgeous detail in M31, M32 and M110 visible
Friendswood, Texas
7
None
3 minutes
1600
Almost all white picture
Friendswood, Texas
7
Light Pollution
3 minutes
1600
Bright blue background, M31 as a fuzzball, M110 visible, M32 not obvious
Friendswood, Texas
7
Light Pollution
2 minutes
1600
Teal blue background, M31 as a fuzzball, M110 visible, M32 not obvious
Friendswood, Texas
7
Light Pollution
1 minutes
1600
Dark blue background, M31 as a fuzzball, M110 visible, M32 not obvious
Friendswood, Texas
7
Light Pollution
1 minutes
400
Very dark blue background, M31 as a smaller fuzzball, M110 visible, M32 not obvious
In October, I got this fantastic picture of the Andromeda Galaxy from Dell City, Texas with its Bortle 2 – 3 dark skies.
Camera geek info:
Canon EOS 60D in manual mode, 179 second exposure, ISO 1600, custom white balance 3500K
Williams Optics Zenith Star 73 III APO telescope
Williams Optics Flat 73A
iOptron CEM40
Dell City, Texas Bortle 2-3 dark skies
I wanted to see what happened when I used the exact same setup and settings from my driveway in Friendswood, Texas with its Bortle 7 (much much brighter) skies. My suspicion was that the picture would be all white.
On my first opportunity to try the experiment, there was also a two days past full Moon in the same section of the sky. As you can see, I did get an almost all-white picture.
I backed off to ISO100 to avoid overexposing the picture, but then I didn’t get near the detail that I got from the dark skies.
I didn’t know how much the overexposure was due to the near-full Moon and how much was due to light pollution.
Yesterday, I got the chance to try the experiment again with no Moon. As you can see, at the dark skies setting, I again got an almost all-white picture.
I backed off to ISO100 and ISO400 to avoid overexposing the picture, but again I didn’t get the detail I did under darker skies.
All of the pictures in this blog post are unprocessed, other than being saved to a lower resolution format. It will be interesting to see what I can get when they are processed.
How dark are your skies?
Site
Bortle
Moon
Exposure Length
ISO
Result
Dell City, Texas
2 – 3
No Moon
3 minutes
1600
Gorgeous detail in M31, M32 and M101 visible
Friendswood, Texas
7
Near Full Moon
3 minutes
1600
Almost all white picture
Friendswood, Texas
7
Near Full Moon
3 minutes
100
M31 as a fuzzball, M32 and M101 not obvious
Friendswood, Texas
7
No Moon
3 minutes
1600
Almost all white picture
Friendswood, Texas
7
No Moon
3 minutes
100
M31 as a fuzzball, M32 and M101 not obvious
Friendswood, Texas
7
No Moon
3 minutes
400
M31 as a larger fuzzball, M32 and M101 barely visible
A few weeks ago, we took my telescope and tracking mount on a road trip to our favorite Air B&B in Dell City, Texas. My telescope and I enjoyed the dark (Bortle 2-3) skies.
Here are some three minute long exposure images I was able to get:
Andromeda Galaxy (M31) plus two satellite galaxies (M32 and M110). The Andromeda Galaxy is the nearest large galaxy to our own, at 2.5 million light years away. Its apparent size is 3.167 degrees by 1 degree. In comparison, the Moon has an apparent size of 0.52 degrees on average. The Andromeda Galaxy filled the screen on my camera – this image is not cropped at all. It has an apparent magnitude of 3.44.
Triangulum Galaxy (M33). The Triangulum Galaxy is the third largest galaxy in our local group, after the Andromeda Galaxy and the Milky Way. It’s 2.73 million light years away, and its apparent size is 1.2 degrees by 0.7 degrees. It has an apparent magnitude of 5.72.
Crab Nebula (M1) with Mars. M1 is the remnant of a supernova observed in 1054. It’s located in the Milky Way, 6500 light years away. Its apparent size is 7 arcminutes by 6 arcminutes, and it has an apparent magnitude of 8.4. Mars, of course, is the fourth planet in our own solar system, and the brightest object by far in the image.
Eye of God (or Helix) Nebula (NGC7293). The Helix Nebula is planetary nebula – the gases expelled from a star before it becomes a white dwarf, lit up by that star. It’s located in the Milky Way, approximately 655 light years away. Its apparent size is 25 arcminutes, and it has an apparent magnitude of 7.6.
Orion Nebula (M42). The Orion Nebula is one of my favorite objects in the sky, and one I’ve photographed before. It’s a diffuse nebula, a cloud of dust and gas that is forming new stars. It’s located in the Milky Way, about 1344 light years away. Its apparent size is 65 by 60 arcminutes, and it has an apparent magnitude of 4.
Camera geek info:
Canon EOS 60D in manual mode, 179 second exposure, ISO 1600, custom white balance 3500K
Williams Optics Zenith Star 73 III APO telescope
Williams Optics Flat 73A
iOptron CEM40
Dell City, Texas Bortle 2-3 dark skies
I’m really looking forward to photographing these from my suburban driveway to see how the images compare. It will be interesting to see if I get a white screen (pure light pollution) at these settings. I’ll let you know!
I’m also looking forward to learning how to stack together a sequence of images with PixInsight to see what an hour plus image looks like. I’ll share that when I figure out how to do it!
Panasonic DMC-GF7 set at f/2.5, 30 second exposure, ISO 800
LUMIX G 14/F2.5 II, 14 mm fixed
Tripod
Camera geek info:
Panasonic DMC-GF7 set at f/2.5, 10 second exposure, ISO 6400
LUMIX G 14/F2.5 II, 14 mm fixed
Tripod
Since summer 2021, I’ve been acquiring some more advanced astrophotography tools (toys?).
My first and biggest acquisition was a new tracking mount with GoTo capability, an iOptron CEM40. This was my first GoTo tracking mount, and it is amazing. It is so much easier to enter the object to point towards and watch the mount rotate to point the camera there than to iterate on camera images to find the object. It is also a beautiful mechanical device. I bought it because of its design and because it is relatively lightweight but could still handle the 8” or 10” telescope I eventually wanted to get. However, it came with a steep learning curve.
One thing I learned was that there are two different alignments that need to be done: the polar alignment to physically align the tracking axis with celestial north, and the GoTo alignment. Just polar aligning is not sufficient.
For polar alignment, the mount comes with a polar alignment camera, but when I got it, the software only ran on a PC, which I did not have (there is a Mac version now, but I have not played with that yet). So I was using the polar iterate align option with the digital display on my camera, and that was a slow, frustrating, and sometimes unsuccessful process.
For the GoTo alignment, I use the three star alignment technique. I read that the mount will try to combine new alignment measurements with the previous ones, so I delete the old alignment data prior to aligning. I also search for zero position to get the mount set prior to doing any alignment.
My second acquisition was a Celestron StarPointer Pro Finderscope. It made a huge improvement in my ability to align the tracking mount over using my camera screen to align it.
My third acquisition was a Williams Optics Zenith Star 73 III APO telescope. It is a 430 mm focal length, 73 mm diameter two element refractor. It is a beautiful piece of hardware. Although it is significantly smaller than what I originally intended to get, I picked it because I wanted to photograph larger objects such as the Andromeda Galaxy and because the larger the telescope gets, the more difficult it is to point. And since I was still struggling with alignment …
My fourth acquisition was a very low end PC to interface with the polar alignment camera. It made a huge improvement in my ability to polar align the tracking mount. What, even with a finderscope, was a slow and frustrating process, is now a less than 2 minute process, and much more accurate.
With all that, and a lot of trial and error, I am now very pleased with the images that this setup is producing. As a teaser, here is a picture of the Andromeda Galaxy (M31).
Camera geek info:
Canon EOS 60D in manual mode, 179 second exposure, ISO 1600, custom white balance 3500K
Space&Aliens 