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Post by Deleted on Apr 22, 2014 11:23:58 GMT
Hello all,
I have been avidly touring the skies with my humble 5 inch GOTO Newt for 2 years now and have been recently fascinated with video astronomy. VA i feel, would quench my need for instant gratification and allow me to see more detail in DSOs (which is what I'm interested in viewing).
Which brings me to my question, Do i absolutely NEED to polar align to get a satisfactory live image?
Would a GOTO 10" Dob be ok assuming polar alignment is not needed?
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Post by Deleted on Apr 22, 2014 15:01:16 GMT
Hello Nexus welcome to the forum! It sounds like VA is the answer to your needs Short answer... no... it doesnt need to be polar aligned. You can get exposures of around 30-60 secs from a ALT/AZ mount without star trails. I cant comment on the Dob im afraid but i know some guys here use them. I believe focal reduction can be a pain... But still possible.
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Post by Dragon Man on Apr 22, 2014 15:09:49 GMT
A tracking Dob would be fine. Even just an Equatorial Platform. But trying to stay on an object long enough without any tracking at all will make it really challenging. Very short exposures may work, like up to 2 seconds. But beyond that the object will have moved too much.
With a GOTO Dob all you need to do is the initial star alignment recommended by the manufacturer and you'll be fine. Field rotation hardly rears its head with Video as we aren't taking 20 minute images like Astrophotographers do. The longest frames you will do will be about 2 minutes. But many objects are easily visible with a few seconds to 1 minute.
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Post by Deleted on Apr 22, 2014 16:56:28 GMT
Can't add much more I like to get mine as accurate as possible good tracking makes life easier with the small fov on my 6in newt.
The GOTO dob would be easier to set up without having to worry about pa.
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Post by Deleted on Apr 22, 2014 19:13:28 GMT
As already said Nexus, you'll be fine. I have being doing VA for just over a year now and always use Alt AZ. I very rarely go over 40 seconds and mostly I'm at 7 - 14 so it's not a problem for me. In fact my mount can actually switch to EQ mode but I've never felt the need to try.
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Post by Deleted on Apr 22, 2014 21:33:08 GMT
I use a 10" goto dob and I've gotten great results.
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Post by Deleted on Apr 22, 2014 21:50:51 GMT
Thank you all for your quick response! Greatly appreciate this information!
I was thinking the Dob due to its low F4.7 ratio, understanding that the focal length with make things a tad hard.. but am wide open to suggestions/tips on the best suited for the job!
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Post by Deleted on Apr 23, 2014 5:21:36 GMT
I got my f4.7 dob down to about f3.2 using a samsung SCB-2000 camera. I use a 2" c-mount adapter and a 1.25" 0.5x FR.
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Post by Deleted on Apr 23, 2014 10:47:02 GMT
Hi nexus,in my opinion speed is first priority for av. Cameras work well in the region of f3 to f5 for DSO work.
For planet work it doesn't matter so much.
Of course reducers speed things up.
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