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Old 25-03-2007, 11:45 PM
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shaneaust (Mick)
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Blurred pic

Hope someone can help me identify what I'm doing wrong with this type of shot - havent had time to check what it is, but I think it's M19, based on its approximate position.

You can see the problem - blurry stars and oversized! I am a rank newbie with the cam I'm using (Canon EOS 300d), and I had it set on ISO 800, bulb exposure of ~ 30 seconds, lens size (?) 90 mm. It is piggy-back mounted on the top of my scope.

Due to image size restrictions on IIS, I've had to crop this a bit.

Any suggestions??
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  #2  
Old 26-03-2007, 04:48 AM
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iceman (Mike)
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Focus! It's out of focus.
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Old 26-03-2007, 06:16 AM
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before imaging, find a nice bright star where you dont have to perform twister to get to the camera's viewfinder. Then focus the drawtube on the telescope back and forth until you see a sharp image. you can then take a few images to confirm you have focus and if not very gently move the focuser a smidgen either way taking images and viewing on the screen on back of camera, dont forget to zoom in and check the stars sharpness.
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Old 26-03-2007, 07:07 AM
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The others may be correct but given that your scope is listed in your sig is a dob, it could also be camera movement. For short exposures (less than 30 seconds; any longer and you will need tracking) you would be better to put the camera on a very sturdy tripod, check the focus on a distant object during daylight and note whether the infinity focus setting marker on the lens is correct. Then it's simply a matter of setting the focus point to the same place when it's dark, without having to rely on star images. It may also be worth getting the mirror lock hack(Firmware) as the mirror jumping up and down will also create enough movement to be a problem.
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Old 26-03-2007, 07:40 AM
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shaneaust (Mick)
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Houghy's advice

hmmm...I understand what you're saying, but how can focusing the drawtube on the scope have any effect on the camera's focus, given that the camera is simply riding piggy-back on top of the scope?



Quote:
Originally Posted by h0ughy View Post
before imaging, find a nice bright star where you dont have to perform twister to get to the camera's viewfinder. Then focus the drawtube on the telescope back and forth until you see a sharp image. you can then take a few images to confirm you have focus and if not very gently move the focuser a smidgen either way taking images and viewing on the screen on back of camera, dont forget to zoom in and check the stars sharpness.
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Old 26-03-2007, 08:01 AM
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Quote:
Originally Posted by shaneaust View Post
hmmm...I understand what you're saying, but how can focusing the drawtube on the scope have any effect on the camera's focus, given that the camera is simply riding piggy-back on top of the scope?
missed that piggy back bit. but the process still remains the same. manual focus.
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Old 26-03-2007, 08:14 AM
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RB (Andrew)
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Quote:
Originally Posted by iceman View Post
Focus! It's out of focus.
Mike is right, it's just out of focus.
Turn your lens focus to infinity, you may need to tweek it a little either way, and try again.
The other tiny coloured dots you see in the image are "hot pixels" from the camera.



PS by the looks of it, the camera has been bumped, you need to use a cable release to activate the shutter.
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