Wesley's Tool-Box

Directly imaging a fast-moving object in the sky like ISS by tracking it manually becomes more difficult with higher magnification. I could barely manage it with the Canon SX50 HS camera with 1.46"/pixel resolution. Using iPhone 6S Plus on the NexStar 6SE telescope with a 9mm eyepiece gives 0.31"/pixel resolution, making the field of view nearly 5 times narrower. Indirect method, which images the moment when the ISS passes in front of another celestial object, is easier because the telescope is focused on a fixed location. This is what I did a year ago. But such opportunity is much harder to come by, so I eventually decided to give the direct method a try with the telescope.

There were many uncertainties, such as what camera settings I should use on my iPhone and whether the telescope's motors would be fast enough. I would have to make guesses and hope for the best. To increase the chances of catching the moments at a high resolution when it entered the view, I used the 4K (3840x2160, 8.3MP) 30fps video recording mode with highest ISO and fastest shutter speed possible. One thing I did manage to "tie down" was the iPhone itself. The Universal Smart Phone Adapter from Modern Photonics that arrived in the mail just in time was the best solution I tried for attaching the phone to any eyepiece I had.

In the end, I was able to capture 22 frames in total out of about 100 seconds of recording. Targeting the space station with a non-magnified finder scope turned out to be quite difficult and focusing was also somewhat tricky. I need more practice to nail these down better. Fortunately, the motor was more than fast enough and the camera settings worked out. Plus, the processed results already outdid the ones from SX50 HS - major parts of the station are much more recognizable. They also explain what I was looking at in the old blurry shots. Looks like I'll be trying more of this in the future.

Telescope: Celestron NexStar 6SE + X-Cel LX 9mm eyepiece
Device: iPhone 6S Plus (afocal)
Settings: 29mm - ISO 720 - 1/1400s - f/2.2
Filters: None
Location: Naju, Korea (time in KST)
Stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

#1: 9 photos @ 2016-06-17 20:39:38
#2: 5 photos @ 2016-06-17 20:40:03

I used the Opteka 2x teleconverter lens for astrophotography for the first time when I took another series of photos of the planets two days ago. This is supposed to be used with telephoto mirror lenses, but that's basically what my telescope is as well and I hoped it would be usable here. Test shots during the day came out alright, maintaining better contrast than the 2.5x Barlow lens I had been using. As you can see here, it performs reasonably well in the night, too.

I didn't originally intend to photograph the Saturnian satellites because they are quite dimmer than the Jovian ones. The four biggest Jovian satellites have apparent brightness in the magnitude 5 range, while the biggest and brightest Saturnian satellite, Titan, is around magnitude 8. The three largest after Titan are of magnitude 10. That's why I didn't take separate photos with longer exposure. Even so, post-processing the background area revealed the dim satellites. I noted their relative positions with the caption. Dione may be barely visible on on well-tuned screens.

Telescope: Celestron NexStar 6SE + Opteka 2x Teleconverter
Device: Sony A5000 (prime focus)
Settings: (3000mm) - ISO 100 - 1/3s - (f/10)
Filters: None
Time: 2016-06-15 00:12-00:13 KST
Location: Naju, Korea
26 photos stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

Yesterday's sky was full of light clouds that became thicker as times passed. It was just enough see very bright stars and planets, so I decided to check how large the planets would appear with my old Tamron 270mm lens on my Sony A5000 camera. Jupiter came out to be about 11 pixels wide, or about 3.3 arc seconds per pixel. I then attached the camera to the telescope and saw that the planet was about 64 pixel wide, or about 0.56 arc seconds per pixel. This is more or less in line with the 1500mm focal length.

Since Jupiter was still somewhat "photographable" even with the cloud cover, I decided to take some more photos and stacked them to produce this nice result with all four Galilean satellites in view. The last time I took a photo like this was three years ago.

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - ISO 100 - 1/2s - (f/10)
Filters: None
Time: 2016-06-10 21:48 KST
Location: Naju, Korea
20 photos stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

As Pluto moved toward the western horizon, a planet started to come into the telescope's view through the southern window - Neptune. It was the first time I had seen it in person, but seeing as how relatively dim it is compared to other planets (magnitude 7.8), I decided to take photos the same way I do for stars.

Sure enough, it was caught on the photos as a moving bright spot, next to a 6.9-magnitude star called HD 214686. But I soon discovered that it wasn't the only object moving. A faint dot of about magnitude 13 was moving considerably faster than Neptune. Given the brightness, it had to be a small but known celestial object.

Consulting the minor planet database revealed the object to be 303 Josephina, an asteroid from the main belt with a diameter of about 100km. Out of pure coincidence, I had caught a planet and an asteroid together on several photos.


But the surprise didn't end there for me. I noticed that Neptune either had a bump or a small dot next to it. It turned out that it was Triton, by far the largest satellite of Neptune with apparent brightness of magnitude 13.5. Photographs taken a day apart clearly shows its changing position relative to the planet, as well. So thanks to the long exposure photography, I was able to take a planet, a satellite, and an asteroid all at once.

Here's the full version of the final frame of the animation, if you want to see it.

Telescope: Celestron NexStar 6SE
Device: Sony A5000 (prime focus)
Settings: (1500mm) - (f/10)
Filters: None
Location: Naju, Korea

#1: ISO 800 - 20s - 2015-09-10 00:14 KST
#2: ISO 800 - 20s - 2015-09-10 01:12 KST
#3: ISO 800 - 20s - 2015-09-10 02:34 KST
#4: ISO 1000 - 30s - 2015-09-10 23:28 - 23:30 KST (3 photos stacked)
#4: ISO 1000 - 30s - 2015-09-11 00:32 - 00:37 KST (2 photos stacked)

It seems that I get to see a "great" transit of the ISS in front of the Sun once every year, with the space station appearing large enough to make it look like the letter H. This time, CalSky was predicting a nearly perfect condition at Naju, a near-center pass with an apparent diameter of more than one arc minute (63.1"). With the weather cooperating, I did not want to miss it.

To make sure I did not miss anything, I took out both my Celestron telescope with the smartphone adapter and my SX50 HS camera. I was hoping that at least one of them would catch the occurrence. I hurried with the setup and had everything ready just barely. I let my iPhone 6 Plus start recording the view through the eyepiece of the telescope in 240fps slow motion video, and pushed the shutter on my SX50 HS in continuous shoot mode, all mere moments before the transit.


The SX50 HS captured just one frame, which was sort of expected. The quality was easily better than my previous attempts thanks to the large apparent size. But the real deal was in the iPhone 6 Plus. It had captured 80 frames of the ISS in motion in total, with each frame besting the SX50 HS's efforts. The 240fps video capture truly shined, creating this smooth slow motion video as a result.


Here's the stacked and post-processed composite of the video in a single picture; click it to see it in full resolution. You can appreciate the details of the ISS and the sunspot AR 12339 quite better this way. If you look at the space station up close as seen in the first picture of this post, it's good enough to identify its major features. I've marked them for your convenience.

Telescope: Celestron NexStar 6SE + 25mm eyepiece + 2.5x barlow
Device: iPhone 6 Plus (afocal)
Settings: 29mm - 1280x720 - 240fps - f/2.2
Filters: None
Time: 2015-05-10 13:33:58 KST
Location: Naju, Korea
Stacked with RegiStax 6.1.0.8
- #1: 12 photos
- #2: 10 photos (ISS, each) / 100 photos (Sun)