Deleted
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Post by Deleted on Sept 9, 2016 20:10:11 GMT
I know that no tracking will severely limit is use, but was wondering what the near real time images would look like in a 14" DOB?
thanks
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Post by davy on Sept 9, 2016 22:19:03 GMT
Think the sensor is a 1/3rd and works in at about the same view as what you would see with a 6mm eyepiece, think it would be hard work trying to keep a target tracked and in focus without a driven mount.
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Post by howie1 on Sept 10, 2016 2:42:38 GMT
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Post by Rick in NWArk on Sept 12, 2016 15:43:01 GMT
In my opinion, and this is theoretical only, but the only decent video astronomy you can do with a non-tracking dob is with the moon (or with the Sun with appropriate filters).
For DSOs, unless you can get your effective focal length to below 480mm, you will have a small field of view / large image scale. What that means is the part of the sky the chip is seeing is small (the objects are bigger) and so the rotation of the Earth moves objects through that small view faster that it does through a larger view. Add to that the fact that most DSOs are so dim that you need more than 5 seconds to gather enough light to see them, and you have a blurry and streaky object.
For Planets, its a bit of a different story. They are brighter, so you will be able to have exposures less than 100 milli-seconds, versus several seconds. But, the problem is that planets are small, so you need to again go to a longer effective focal length to get a decent sized object. Now you have the movement problem again. Maybe you can get some results here, but you'll be constantly moving the dob to get it back into frame. If you use a Barlow to get a bigger planetary disc, you'll struggle a bit - your dob will need to be right next to your monitor!
For the moon (and sun) you have bright objects that are big enough that you can let the Earth's rotation move the field of view and you can get nice results. You're going to be in the single digits of milliseconds here with a camera - your big dob is going to really saturate the camera's pixels. You're still going to obviously have to move the dob, but a little less frequently if its past 1st quarter.
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Post by Dragon Man on Sept 13, 2016 11:33:12 GMT
Here's an example of Video Astronomy through a non-tracking Dobsonian. These videos show that it can be done but not on DSO's very successfully unless it's a very bright DSO. MOON: JUPITER: SATURN: VENUS: a faint RING NEBULA: and some hand held observing: To keep objects in the FOV with a non-tracking dob is done in exactly the same way as when using an Eyepiece, by hand tracking.
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Post by davy on Sept 13, 2016 13:20:32 GMT
Was surprised by the moon on 10" DOB,,done non tracking on it before with scopes just not over 8",,, but deffo hard work.
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Deleted
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Post by Deleted on Oct 15, 2016 13:03:15 GMT
thanks to all - I did pick one up used so we'll see what I can do!
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Post by davy on Oct 15, 2016 14:48:52 GMT
Looking forward to what you can achieve
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Post by Dragon Man on Oct 15, 2016 15:44:20 GMT
thanks to all - I did pick one up used so we'll see what I can do! Excellent. I look forward to reading about your results.
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Post by Rick in NWArk on Oct 17, 2016 13:54:46 GMT
thanks to all - I did pick one up used so we'll see what I can do! Congrats! Feel free to share your results and experiences.
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