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Lawrie
Joined: 25 Sep 2008
Posts: 13
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 Posted: Sat Nov 15, 2008 9:22 pm Post subject: Dobsonian Counterweight |
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My Skywatcher 150P has only friction tensioning and no provision for balancing anything much heavier than eyepieces. When a camera is attached a simple counterwieght is desirable if not absolutely essential. A fabric dog collar of the appropriate size to go round the tube with a small weight attached does the job. It can be slid along the tube to get balance and being fabric it won't scratch the tube. The weight, (in my case an old brass padlock) is looped through the "eye" which normally the dog lead would be clipped.
Just an idea but very effective.
Lawrie |
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bigbry49
Joined: 09 Jan 2008
Posts: 17
Location: Worcester
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| Posted: Sun Nov 16, 2008 3:54 am Post subject: |
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Nice one, Lawrie!
OK, what camera and what are you photographing (imaging in 'astrospeak')?
Are you driving the 'scope or just snapping the Moon & planets?
Bryan (under clouds) |
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Lawrie
Joined: 25 Sep 2008
Posts: 13
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| Posted: Sun Nov 16, 2008 1:06 pm Post subject: |
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Hello again. Glad to hear from you.
My camera is a Canon 350D, unmodified. It fits on to the focuser with a standard screw- fit to bayonet adapter. I use it (when I get the chance) for the Moon which is bright enough to take fast shots without worrying about tracking. To keep it simple I let the camera download the image in jpg format. Quite enough for the Moon.
The camera is set to Manual and the ISO speed to 100. The shutter speed I find is about right at 1/50 to 1/200th, depending on how bright the Moon is.
The image in the camera eyepiece or screen is bright enough to focus easily.
I haven't tried it on planets because the image size, used in this way, is not big enough. Anyway the Moon has more than enough detail to keep me interested!
Let's hope for some clear skies some time!
Lawrie |
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