Wesley's Tool-Box

One of the main reasons I decided to buy a new camera was that it would yield a lower-noise photo at high ISO settings, making it better for long-exposure astrophotography. To confirm this, one of the first objects I chose to take photos of was the dwarf planet Pluto.

It moved a little to the east since the last time, already past the ξ2(Xi 2) Sagittarii and not near a particularly bright star. The brightest stars in the animated frames above are only about magnitude 11. Nevertheless, Pluto was discernible when comparing the two frames taken a day apart under a bright monitor. Dimmest stars visible reached magnitude 15, and Pluto itself moved clearly enough to see that it's not a background star.

If you feel particularly bored, you can try picking it out of the full version of the September 10 photo.

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

#1: ISO 800 - 20s - 2015-09-09 22:09 KST
#2: ISO 1000 - 30s - 2015-09-10 21:44 KST

My Canon EOS 450D DSLR camera is a fine equipment, but it is showing its age. So I decided to invest in a new equipment but not at too much expense. After much comparing, I decided to go with A5000, an entry-level mirrorless camera from Sony. It's got a highly sensitive sensor for its class, yet it's currently selling at quite a discount - about US$280 with a 16-50mm bundled lens, or just under US$200 for the main body.

As I ordered this camera, I also bought a T-ring for its E-mount lens mount so I could install it on my Celestron telescope. What you see above is how the camera looks with this attachment. I only took a handful of photos with the bundled lens before replacing it with the T-ring to start photographing the stars. I'm keeping the lens around just in case I need to shoot regular photos.


And this is how my new astrophotography setup looks like. The camera is practically the lightest APS-C sensor-based mirrorless camera out there, so it hardly burdens the telescope. I can also use my smartphone to remotely control the camera - a convenient feature that also prevents shaky images. I'm hoping to get some nice photographs out of this, so stay tuned.

For the past few weeks, clouds and rain due to the monsoon prevented me from seeing a clear sky at night. But that period is nearing its end, and last night I had a near-perfect opportunity - no clouds and no haze. Brightness of the first-quarter Moon was about the only fly in the ointment.

As I was only able to observe the southern sky out the window of my room, I consulted a star chart to see if anything interesting was there to see. Pluto immediately caught my eyes. As you might know, this dwarf planet is making headlines at the time of this writing because the New Horizons probe made a flyby two weeks ago. The unprecedented details of the images from the probe is capturing public interest, and mine. So I wondered if I could see a glimpse of it with my own telescope.

Problem is, Pluto is very faint - 14.1-magnitude right now. Based on my past observations, it would be at or just outside my limits even with astrophotography. Sure enough, when I pointed my telescope to the right position, I couldn't make it out visually. So I attached my DSLR camera and took several long-exposure photos in hoping that they'd be more revealing. One of such result is the photo you see above. The brightest star is ξ1(Xi 1) Sagittarii, a 5.1-magnitude star. Most of the rest are fainter than 10-magnitude.


After carefully comparing the photo with a detailed star chart, I finally found a dot that didn't belong to a star. This seemed to be Pluto that I was looking for. But to make sure, I compared all the photos I took over the span of about an hour and looked to see if there was any movement - a telltale sign that it's not a star, but an object moving around the solar system.


Indeed there was. This was the dwarf planet I was looking for. This process of comparison was basically how Pluto was identified and discovered in the first place back in 1930, so it was pretty satisfying to retrace the steps. I'm also glad to know that the southern sky at Naju is still dark enough to see this faraway world.

Telescope: Celestron NexStar 6SE
Device: Canon EOS 450D (prime focus)
Settings: (1500mm) - ISO 1600 - 30s - (f/10)
Filters: None
Time: 2015-07-26 00:06 - 01:13 KST
Location: Naju, Korea

On the Memorial Day in Korea earlier this month, the night sky was clear and had three planets shining brightly in the sky at the same time. I took my astrophotography equipment outside and got some burst mode photos of the planets.

It seemed that Venus was quite bright and the default camera app didn't have enough adjustments available to make it dark enough to reveal any details on the half-disc. Also, Jupiter now being in the lower altitude hampered the details somewhat. Other than that, things turned out fine. It was nice to have a direct comparison of the apparent sizes between the planets.

Telescope: Celestron NexStar 6SE + 5mm eyepiece
Device: iPhone 6 Plus (afocal)
Filters: None
Location: Naju, Korea
Stacked with RegiStax 6.1.0.8

Saturn
Settings: 29mm - ISO 400 - 1/15s - f/2.2
Time: 2015-06-06 21:44 KST
30 photos

Venus
Settings: 29mm - ISO 250 - 1/30s - f/2.2
Time: 2015-06-06 21:40 KST
100 photos

Jupiter
Settings: 29mm - ISO 320 - 1/30s - f/2.2
Time: 2015-06-06 21:16 KST
100 photos

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)