Friday, August 27, 2010

Items still for sales

Price for local Hong Kong transaction:-

1. APM 1.25" Herschel Wedge with heat sink, 1.25" B+W ND3 and polarizing filter (must be used together with the wedge), all for $1800. (SOLD)

2. Orion 100ED f/9 OTA with rings at 7lb only + Unistar Light mount with 3/8" interface at 2lb, both for $3999. Very portable actually. (SOLD)

3. Lumenera LU070M with DIY Peltier cooler, $3000. Last one that I'm trying to sell, I will keep the other one. (SOLD)

4. Astrotrac with original polarscope, original box and paper work, $4200 only, it's over $5000 new. I only try it for a couple of times at home, not suitable for my original plan, virtually new. (SOLD)

5. Shoestring Astronomy FCUSB: USB focusing controller compatible with JMI focusers, etc. $500 HKD, virtually new.

Sunday, August 15, 2010

20100815 Sun

Get back home, see the sun, pulled out my setup. The iOptron works now but I had little time to test it. It's cloudy and I never got a clear sky, so I didn't even open the window of the air-conditioned room, hey, it's lie 34 degree Celcius outside!

Just a record, very poor image indeed. Registax couldn't really process this video with moving cloud. avistack does not like 12-bit video it seems.

AR1093 and AR1099 just before their departure.

Saturday, August 14, 2010

Testing the Astrotrac on the moon with 100ED

Back home and saw the moon hanging low in the sky, I got the chance to try out the Astrotrac with my Orion 100ED. I secured all the joints but when I put my 100ED OTA on it (without the lens), the 3/8" screw just slips. With just a simple screw to fix the 410 head, I found that it cannot hold the heavy weight at all.

The verdict is out, I shall keep my TG-SP II since the apparently more capacity of the Astrotrac does not work in my case. At the same time, I shall also further lower the price of my Orion 100ED f/9 since I ain't going to get a mount enough to use it. In the mean time, I will keep the Orion 100ED f/9 first so that I might be able to do some visual scanning with my Unistar Lighter. But the Astrotrac is going to be sold. Don't get me wrong, there's nothing bad with it, it just couldn't fit my original intended purpose.

Friday, August 13, 2010

Perseids 2010

I did nothing basically, just setup my camera, pull my curtain to cover the camera from indoor lighting. Start the timer release, and let it go for 3 hours. The weather report said that it could rain so I kept my window closed, so I was taking picture through the dirty window glass. And worst yet, the reflection from outdoor lighting even washed out some more contrast, dimmer meteor could render invisible.

Under my heavily light polluted sky, I was forced to stay at 35s exposure each at f/3.5 ISO 400. I did capture some stars and aereplane trails, but there's nothing else. Maybe south-west is not a good direction afterall?

This morning, I examined all the frames but found nothing. Local folks reported a few meteors and one of them said it was the worst Perseids that he has ever seen.

Wednesday, August 11, 2010

An alternative way to mount the Astrotrac

Just found an alternative way to mount the Astrotrac on the Takahashi mini-wedge originally for the TG-SP II. This wedge is too small such that the Astrotrac might hit the tripod legs. To solve this problem, I've mounted a small quick release platform between the tripod and that mini-wedge, and the wedge was effectively raisen and thus the Astrotrac will not hit the tripod legs.

A very good side effect is that, that quick release platform enables me to rotate the wedge with respect to the tripod. That means I can fine tune the polar alignment in azimuth!

If I stay in Hong Kong, I've no need to buy another wedge or another ball head as a result of this newly found configuration. I can use this combination on the planets because the 410 head can be used for fine adjustment even with my Orion 100ED, and it is also good for the sun or the moon.

If I were to travel, my prime target will be wider field imaging, and in such case, I will only need to buy a simple ball head. And the 410 head will be reserved for polar alignment.


A side note: The Astrotrac is really light by itself. However, you need two more tripod heads (e.g. two 410) for proper operation, and thus, the weight is tripled! Therefore, it's indeed similar with a TG-SP II.

Of course, the Astrotrac has more capacity. And if you do photography along with your trip, all you need is one more tripod head plus the Astrotrac. Therefore, it's not bad afterall.


To do: I shall try out the Astrotrac + Orion 100ED on planets, moon and the sun with a Herschel Wedge, if it works, I shall definitely keep the Astrotrac and sell the TG-SP II. Otherwise, I shall conduct a few more tests.

Thursday, August 05, 2010

Trial setup of the Astrotrac

The Takahashi wedge (originally for Sky Patrol):

A Tele Vue Ranger attached:-

Tripod: Gitzo G106
Wedge: Takahashi (TG-SP II)
Head: Manfrotto 410

I found that the whole setup is pretty close to the window frame, that's good for me since it might indicate that I can use it for indoor imaging. If that's the case, it can replace both my TG-SP II as my portable setup, and my iOptron SmartStar-GPS for indoor imaging. I need to have some real sunshine to confirm this.

Tracking was very stable as I can detect from the eyepiece, at least noticeably better than that of the iOptron. The whole thing is very stable indeed. The first thing which I missed is a hand controller like the TG-SP II, but of course, I can do it manually with the 410 head which should be at least as good. For higher power imaging or observation work of the sun, moon and the planets, I'm sure electronic slewing is much more preferred.

The whole setup is a little bit lighter than that of the TG-SP II, but the difference is not big.

Wednesday, August 04, 2010

Brief impression of the AstroTrac

I would say it's very attractive, it's compact and light weight.

However, when compared with the Takahashi TG-SP II, I would say the Takahashi should last longer. The parts are better made, the electronics are simpler and it should last longer. The Astrotrac is a bit too long, and the parts are not very thick, and it could deform over time?

Featurewise, the polarscope of the Astrotrac is better. It comes with an illuminator and it's bigger and more accurate. The Takahashi is too small and very hard to use when placed side by side. The Astrotrac has an autoguider port while the Takahashi has none.

Having said that the Astrotrac can hold more weight and it's lighter. There is no counter weight for the Astrotrac and you can hardly forget anything when packing up for the trip.

I should try the Astrotrac shortly, and see which one I should keep in the long run.

Tuesday, August 03, 2010

20100802 to 0803

I just hand a chance to stay in a local resort for a night with my family.

The sky was not dark afterall as we were still within Hong Kong but I knew that we would have a large balcony, so I packed my TG-SP II inside the suitcase. Yes, it's very light weight and compact so that it would not affect my kids' stuff. Otherwise, I would not have brought it along.

When I was about the setup the whole thing, I found that I missed the dovetail at home! So, I really couldn't mount my DSLR on the mount finally.

Guess what, this accident reminded me that I really didn't use my TG-SP II enough. I would still miss some bits and pieces at home...