Tuesday, July 13, 2010

Preparation for urban wide field imaging

Guess what, I even want to try imaging in the urban center... see what I can get?

But before I can try, I will need to try out the combinations of equipments first. With my newly acquired TG-SP II polarscope, polar alignment could be done faster.

First of all, I need to determine how many counter weight that I will need to use, and without much surprise, this little mount can take my Canon 450D plus a 100mm f/2 or a 50mm f/1.8 without any counter weight. It is because the RA motor was placed strategically to serve as a counter weight.

Therefore, the whole setup is really extremely portable. All I need is a small tripod, the mount without counter weight, a battery box plus the hand controller. I'll also need the timer release so that I can do exposure longer than 30 seconds. Of course, maybe 30 seconds would be too much under such a sky! I shall test run tonight in an indoor setting.

Indoor Test

Finally setup everything, and without Polaris, I can only roughly align the mount by using a compass. By using ISO 400 and f/2, 10s exposure will nearly saturate the whole frame. Star remains pinpoint, and there's no purple fringing... Canon 100mm f2.0 seems to be a good lens indeed.

By stopping it to f4.0 and exposure at 30s at ISO 100, I'm trying to test the tracking accuracy of the mount. Star remains pinpoint! Seems like my rough alignment is not that bad afterall.

Then I centered at Antares and let it go for 20s at f/2.0 ISO 200, M4 was clearly seen. If the sky is darker, I'm sure that it's going to be fun! If the sky is still alright tomorrow night, I shall go out in a nearby open area, I just wish that I can do 30s at f/2.0 and ISO 400 or even 800, I don't need the timer release indeed.

See the hint of M4 in the above shot.

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