Wesley's Tool-Box

Nearly two months ago, I realized that the southern window at home provides a view of the Milky Way with long-exposure photography. Although the result from that time was satisfactory, I felt that a stacked approach would be even better. And now, you see the result of stacking eight photos. It's indeed much smoother even at a larger size.

By not using a star tracker, though, the stars were subject to lens distortion at the edges. This is where the flaws of the bundled lens of the A5000 become quite apparent. But I decided to leave it like this since it draws your attention to the center.

Device: Sony A5000 + SELP1650 (E PZ 16–50 mm F3.5–5.6 OSS)
Settings: 16mm - ISO 1000 - 20s - f/3.5
Filters: None
Time: 2016-08-29 21:48-22:05 KST
Location: Naju, Korea
8 photos stacked using Pixelmator

This year's Perseids meteor shower was predicted to be prominent, garnering lots of public interest. Unfortunately for someone in Naju, the northern sky that the shower was to take place is polluted with light from Gwangju, making it hard to watch the fainter ones. To get a better view, I moved about 17km southwest to the Naju Bannam tumuli (ancient tomb mounds that encompass Sinchon-ri, Deoksan-ri, and Daean-ri tombs) next to the Naju National Museum. Upon arrival, I was disappointed to discover that the light pollution was still quite bad.

It was still better than being at home, so I set up my camera with the Deoksan-ri tombs #2 (left) and #3 (right) in front. There were already two families nearby who came to watch the sky. In the two hours I stayed, I was able to watch about five meteors falling, far less than the supposed maximum of 150 per hour. Of those, the camera caught two of them, the most striking one being shown here. The streak was going through the Andromeda constellation; the fuzzy dot to the left of the streak is the Andromeda Galaxy.

Meanwhile, the airplanes appeared much more often in the sky - there was one every five minutes or so. This is due to being more or less in the direct path of the flights between Seoul and Jeju, as well as Incheon and Southeast Asian cities. Even in this photo, the Mandarin Airlines flight AE231 (Incheon-Taipei) was caught on the left as a knotted line.

Device: Sony A5000 + SELP1650 (E PZ 16–50 mm F3.5–5.6 OSS)
Settings: 16mm - ISO 400 - 15s - f/3.5
Filters: None
Time: 2016-08-12 23:37:27 KST
Location: Naju, Korea

When you try to keep up with fast-moving objects with the manual control of the telescope motors, the lack of fine-grained steps become a big limitation. Speed 6 moves at about 0.267 degrees/second and 7 at 1 degree/second, while the International Space Station moves at a speed that is somewhere in between, depending on the distance. To alleviate this slightly, practice and preparation were needed. I fixed the finder scope misalignment and added a camera mount to the telescope. iPhone 6 Plus was placed on the mount to act as a secondary finder scope, much like what I did on my Canon SX50 HS camera three years ago. These made it much easier to have the telescope point at the International Space Station.

As a result, I managed to photograph about 220 frames of the station in two minutes this time, enough to show the movement like the one I did with the old camera two years ago when I came to Naju. The space station was farther away and a lot dimmer (504km vs 685km, -3.5 mag vs -1.6 mag at culmination) than the previous attempt with the telescope, meaning less details. Even so, I think I was able to identify the SpaceX Dragon spacecraft that went up for the CRS-9 mission, which was attached to the bottom of the Harmony module just ten days before.

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
Date: 2016-07-30 KST
Location: Naju, Korea
Stacked with PIPP 2.5.6 and RegiStax 6.1.0.8

Photos: 10 / 9 / 12 / 6 / 9 / 12 / 28 / 4 / 10 / 14 / 8
Time: 20:18:58 / 20:19:07 / 20:19:12 / 20:19:26 / 20:19:39 / 20:19:41 / 20:19:45 / 20:19:50 / 20:19:58 / 20:20:06 / 20:20:12

A few hours after walking in the rain to see a movie yesterday, I was getting ready to sleep. Then I noticed that the sky was crystal clear, something I haven't seen in more than nearly two weeks (or three, in the night). Not to pass up this opportunity, I got my camera out. With so many stars visible, I wondered if the Milky Way Galaxy could be captured even with all the lights from the apartment buildings nearby.

After a few tries, it became clear that indeed it could be done, if somewhat faintly. Adjusting the levels, curves, and contrast brought out further details. Individual colour channels were untouched, yet the sky showed a very nice gradient. This may be an unintended affect of the light pollution near the horizon and I like how it turned out.

Device: Sony A5000 + SELP1650 (E PZ 16–50 mm F3.5–5.6 OSS)
Settings: 16mm - ISO 2000 - 20s - f/3.5
Filters: None
Time: 2016-07-08 00:44 KST
Location: Naju, Korea

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