Saturday, January 17, 2015

Comet Lovejoy C/2014 Q2

Comet Lovejoy taken at Cainta, Rizal, Philippines on 2015-01-02. My setup for this image:
- Canon EOS-M
- Skywatcher ST-80
- CG-4 mount

 Comet Lovejoy taken at Sembawang, Singapore on 2015-01-16. My setup for this image:
- Canon EOS-M
- Tamron 70-300mm
- Vixen Polarie

Friday, May 2, 2014

Planetary Imaging Without a Tracking Mount

At home, I used to do some planetary imaging with a basic CG-4 tracking mount, a digicam and a small 102mm Skywatcher maksutov telescope. Now that I am in a foreign land, imaging becomes a bit harder due to the absence of my equatorial mount. To make imaging possible, I bought an inexpensive stable tripod for the telescope - a standard video tripod.

The first thing I do is to make sure that the finder scope is aligned properly. Try to center the planet visually first with a low power eyepiece followed by a medium power eyepiece. Realign the finder to make sure that what is at the center of the eyepiece is also centered on the finder. An accurate finder is a must here, I use an optical finder with crosshair. Red-dot finder is probably not a good choice for this kind of imaging.

Once alignment is done, I attach the camera and set it in video capture mode. Make sure that the focus is as accurate as possible when the planet is in view. As most digital cameras do not have a manual focus while in video mode, I opted to focus with the telescope focuser instead. To give me a longer amount of time to focus, I point the telescope to a spot where the planet will drift in place all by itself. Depending on the magnification used, it takes the planet around 15 seconds (for my particular eyepiece) to drift from one edge of the camera frame to the other. The trick here is to center the planet first then nudge the tripod control a little bit in the proper direction. This step will usually take some time and effort to get right, especially if you don't have a slow-motion control, like I do.

Once focus is as close to perfect as possible, it is time to do the actual imaging. Do the previous step again to let the planet drift in place, but this time, also start recording before the planet even appears in the frame. This will avoid the shake that will occur if you were to press the record button when the planet is already in the frame.

I usually repeat the focus and capture steps to make sure that I have a clip that has the best focus.

Here is my setup.

After the hard part is done, it's time to pack up and start processing the image.

Sunday, October 27, 2013

Back to Bukit Timah 2013-10-20

I went back to Bukit Timah for more calorie burning activity, following a 32km bike ride from Sembawang to MacRitchie and back a day earlier. I also wanted to test how fast I could reach the top at 163m from the visitor center at the base. After a non-stop hike, I recorded a time of 11 minutes 33 seconds. I believe I still have the capability to do it still a bit faster, but that's about my fastest record for now.

When I reached the top, I took a short rest before I continued exploring the side trails. This time, I took the Catchment path which basically leads down to the area that links Bukit Timah Nature Reserve to the Rifle range road connecting to Macritchie Nature Reserve. At one point along the path, I heard a knocking sound and saw a silhouette of a barbet borrowing a hole on a dead tree trunk for a nest. It was a big mistake that I usually don't have a tripod with me. The area is under a forest canopy and backlit. I tried to hold the camera as steady as I could, but I just couldn't get a sharp image. With an equivalent focal length of 840mm and an exposure of 1/200 at ISO1600, the image I got was a bit dark and unsharp, so I tried to find something to stabilize the camera. The best stabilizer I got was a tree trunk that I pushed my camera to by applying a force to stabilize the horizontal motion, but not vertical movement. It allowed me to do a 1/160, but I was not satisfied with the sharpness. The best result was not sharp enough even to my low standard and it was also a lifer, so I really wanted a good shot.

Red-crowned barbet

After a few minutes, I have to gave up even though I don't really want to. I also heard the sound of thunder earlier, which kept me from staying longer, since I don't want to be in the middle of the trail when it rains.

As I reached the end of the current trail, I found myself in another trail designed for bikes. A few meters from the intersection, I saw a black bird  which I couldn't identify properly because it's partially hidden and in a bad angle. I tried to take a photograph and came up with just one shot before it flew away. Based on the image, it looked like a drongo-cuckoo.


At the end of the bike trail, I reached a familiar paved road which I took a few months ago with my schoolmate. At one bend, I heard a woodpecker pecking at a branch. I managed to photograph the Common flameback, but it could have been better if I had a tripod.

 Common flameback

I followed the road, but unlike my previous experience, I took the side trail just before reaching the road. Along the way, I saw some bee-eaters, but the lighting was so bad and the birds are too far to get any good pictures.

This side trail took me back to the Bukit Timah visitor center. Just as I walked out of the canopy, I saw movements on the shrubs beside a house I got curious and tried to get a picture of it. As I approached, it went deeper so I stopped, took a couple of shots and observe. I initially thought it's a spotted dove. But as it moves, I noticed that it looks more like a bulbul. I tried to take more shots, but after 2 exposures, it moved deeper into the vegetation which I could no longer follow.

Straw-headed bulbul

I reviewed the images I got and only one turned out acceptable. I incorrectly identified it as an immature Olive-winged bulbul.

I continued walking to the bus stopped and took a bus home. When I got home, I was able to identify the barbet as a Red-crowned barbet. After posting the images online, a friend informed me that the bulbul is a Straw-headed bulbul, that makes it another lifer for me.