Post by Chicago Astronomer - Astro Joe on Aug 10, 2007 7:09:54 GMT -6
Using the Canon Powershot S3 to Capture the Perseid Meteor Shower 2007
I am going to try the S3 and try to catch some Perseids myself.
The only thing is that one never knows when a good one is coming, so it's luck trying to image with only a max of 15 seconds the S3 provides. The meteors as they enter the Earth's atmosphere can appear anywhere in the sky, but as the Earth turns onto open space at 12 midnight, the source will hit the planet head on. Sometimes this is not desired, as the trail is now shortened - coming right at you - as opposed to a long streak shooting past you. But meteors are unpredictable. I have heard larger meteors "pop" and make a sound, but that's rare. The slower moving ones are really cool to follow and many leave a smoke trail behind them. Most dust grain will flare up white, but occasionally the more exotic ones will burn yellow, green and even red.
The advice already provided is good. I will start out with a freshly low level formatted SD 2 GB card and two sets of freshly recharged eneloop batteries for the session. (Great batteries!)
For the bulk of exposures: Steady tripod, 400 ISO max, Tungsten WB and I would experiment with an wide open and closed down aperture exposures. Each one providing unique attributes of composition.
A full 15 sec exposure will create mini star trails, but that's ok, as it lends a circular directional contrast to the straight direction of the meteor(s) line of travel. Again, experiment with various time exposures. If you live in a light polluted area, the less exposure time will cut down on the undesired ambient scattered light - washing out the fainter meteors and causing ugly sky glow in your exposures. Although the 800 ISO is much too grainy, try it, as you might capture the fainter meteors. Most of the graininess can be eliminated in Noiseware software.
Using a teleconverter would cut down in the field of view, but at the same time, sharpen the image and if lucky...grab and magnify a great meteor. I would take exposures with and without the TC.
Use the self timer to eliminate possible vibrations. I set mine for 2 sec delay. The intervoltameter is a good idea if you just want to set-it-and-forget-it. I just may try it.
The source or "radiant" of the shower will be from the Northeast and I would start a session starting at 11:00 pm and well into the following morning. The higher up, straight up or "Zenith" is better for reducing light pollution. Here in Chicago, there is a quite evident circle straight above where there is contrasting darker sky.
I am torn between making exposures in the small format and the large format. In small format, the turn around write time to the Sd card is greatly shortened and the chance of capturing more meteors is enhanced. In large format, you get a much superior detailed image, but the write time to the SD card is slower...and while it's writing, a good one might zoom overhead while you wait. So, it's a toss.
This will be a good exercise for our S3's and anticipate the results worldwide.