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Old September 17th, 2004, 12:24 AM   #1
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why can't I shoot the stars ?

last night , the sky was so clear and so charming!! but when I pointed my camecorder to the sky i can see nothing, is it because of the lights from City ?
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Old September 17th, 2004, 12:53 AM   #2
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The eyes, particularly young eyes, are the most remarkable cameras of all. No camera, least of all a video camera, can match their ability to adjust to such dim conditions.

Those stars are far too dim and small for a little video camera to capture very well. Occasionally you'll see someone capture a bit or aurora borealis footage but even that is very rare and generally pretty dim (compared to what your eye would see). Astrophotography is the general field of shooting the stars (and planets), generally with a still camera. It requires some $pecialized gear and very long exposures.
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Old September 17th, 2004, 03:15 AM   #3
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And yes, lights from the city will interfere with this as well.
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Old September 17th, 2004, 07:28 AM   #4
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Video astrophotography isn't as difficult or as costly as previous posts indicate. The key to shooting faint celestial objects is to increase your light gathering efficiency -ie. use a telescope with a large lens or mirror. I have seen amazing images of last year's Mars closest approach shot with a 8mm camcorder held on a tripod next to the eyepiece of a 6" newtonian reflector telescope. The advantage of video is that in post processing, you can frame grab the best images and stack them with co-registration to get a more detailed image than the eye could perceive.

Modest size telescopes (3" - 8" aperture) are fine for video of the naked eye planets, moon, and sun (with proper filtration). Not only do you increase light gathering ability, but you also increase the image scale on the camcorder CCD. I have a 4"refractor and have used it many times to display live images of sunspots to school groups. Many larger cities have amateur astronomy clubs and the members are generally friendly and willing to work with newbies interested in anything astronomy related.

As for cost, a decent 6" newtonian reflector can be purchased for about the cost of a Flowpod stabilizer. It is specialized, but very well within the reach of many on this forum.

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American Association of Variable Star Observers
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Old September 17th, 2004, 07:45 AM   #5
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That is great Joseph, thanks. Do you happen to have a $ indication
(don't know how much a flowpod costs) and perhaps some links
to the equipment you are mentioning? Thanks again.
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Old September 17th, 2004, 08:03 AM   #6
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Rob,

I am not in anyway affiliated with the Orion Telescope company, but I have purchased from them in the past and found the service and merchandise quite satisfactory. Their webpage:

www.telescopes.com

They market their own line of telescopes as well as Meade and Celestron. They have great customer service and are knowledgeable telescope users. Sort of the B&H of telescope stores. 6" reflecting telescopes and 4" refractors with mounts cost less than $400. Hope this helps.

Joseph
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Old September 17th, 2004, 10:31 AM   #7
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Hey, thanks very much for that information, Joseph! We've actually had very little information posted here on this subject.
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Old September 17th, 2004, 10:53 AM   #8
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I asked about this same thing two years ago. I looked for awhile and remained mystified as to the process.

Do you film the eyepiece of the telescope?
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Old September 17th, 2004, 11:11 AM   #9
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Ken,

You can go prime focus, meaning you use the telescope as an extremely long focal length lens. You just couple or slide the camcorder lens up to the drawtube on the telescope.

OR

You can use eyepiece projection where an eyepiece is mounted in the telescope drawtube and the camcorder is placed behind it so the eyepiece acts like a relay lens. Much higher magnification is achieved in this configuration, but any imperfections in the optical system are also accentuated.

For solar and lunar imaging, I use a 4" aperture, 1500mm focal length refracting telescope. For those familiar with optics, this is a very slow f/15 lens. It works well with bright objects for high detail imagery.

For fainter objects, you need a faster optical system such as an F/4 or f/5 short focal length refractor. I made such a refractor from a research grade cemented doublet lens formerly used by Kodak to test other lenses. The lens is 125mm aperture with a 500 mm focal length. I use a 50mm eyepiece to achieve 10x magnification and piggyback a small optura 10 camera behind it. At star parties, I can display a live image to a small crowd.

With my longer refractor, if I allow the lunar surface to drift through the field it gives the sense of being in an Apollo lunar module drifting over the moonscape. It has real WOW crowd appeal.

Joseph
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Old September 17th, 2004, 12:33 PM   #10
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Thanks for that description.
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Old September 17th, 2004, 02:25 PM   #11
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I have tried to shoot stars and planets before with video, if you don't have a telescope, you can use a video camera with a big zoom (or added tele convertor), I used a Sony Digital 8 cam that has a native 25x zoom lens.

You do have to use a slow shutter speed though or you can't really see very much, and a tripod is required. The results were ok (a bit grainy) but I could get an image of Jupiter and its larger moons that was quite good. For the real deal though a telescope would be better of course.

I have seen amazing results with people connecting a web cam to a telescope, and surely a video camera would be even better.

If you want a wide non-tele shot of constellations etc, a still camera with long exposure times and good tripod can work well, and I have done this myself, and you can get great images.

Dave.
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Old September 18th, 2004, 06:38 AM   #12
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You can get an idea of the amazing pictures amateur astronomers are getting with digital cameras by going to:

www.cloudynights.com

Go to the forums section and then scroll to the photos part. I have seen an occasional thread on use of video in this respect.
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