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Old 29-11-2007, 01:37 PM
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JohnH
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Carry and Plonk aligment

I do not have an obs or pier (donations accepted!) so have to setup and tear down each session. As I am mostly into AP I am keenly interested in getting a fast but accurate alignment.

To help I have drift aligned previously and then locked off the ALT and AZ adjustments and marked out the position of the tripod legs. I "home" my mount at the end of a session BUT desopite this my first slew of a new session is rarely very accurate. I find the star is in the finder but not in the DSLR fov (45'x68'). I take care with the date/time/level so I am guessing my main error is in AZ. So is it sensible to make an AZ adjutment to get the star as close to centre in the fov as possible before doing any other alignment. I have done this on occasion and it seemed to help, other times it seems to make matters worse and I have to go back to drift alignment.

I have thought of using my laser pointer and placing a target at a suitably distant spot in the yard to establish a home reference point but am wondering if it is worth it - perhaps other errors outweigh the tripod position error.

Any tips out there? What do you do to get your portable system aligmned fast?
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  #2  
Old 29-11-2007, 02:48 PM
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ballaratdragons (Ken)
The 'DRAGON MAN'

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Join Date: Jan 2005
Location: In the Dark at Snake Valley, Victoria
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Before I had the advantage of an obs, I covered my mount (scopeless) with a tarp, and tied it on so it couldn't blow away.

The mount is too big to be put away and brought out each time, so it was permanently outside but covered. I know others who do this too. As long as the mount is covered from the weather it'll be OK. Just bring the scope in after each session.
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Old 29-11-2007, 03:07 PM
Dennis
Dazzled by the Cosmos.

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Hi John

Yeah – the lack of a permanent observatory and a full time assistant sucks; now I know why Dr Fred Watson always looks so cheerful!

Like you, I have tripod leg locations marked out. I got the EM200 mount polar aligned (using the built in PAS) and marked the leg positions. I then sunk 200mm long off cuts of 100mm PVC drainpipe into the wetted earth, slightly below the surface for mowing purposes.

I now plonk the 3 legs in the centre depression in each of these locations and using the EM200 PAS, touch up the polar alignment, which is rarely more than 10 to 15 arc mins off, when I first look through the PAS.

After that, I do the one star alignment and I’m up and running. On a night where everything is going well, this procedure takes less than 5 mins, end to end.

Cheers

Dennis
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Old 29-11-2007, 04:06 PM
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[1ponders] (Paul)
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I'm similar to Dennis, except I use K3 and I'm up and away in about 10 - 15 min normally.
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  #5  
Old 29-11-2007, 07:26 PM
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Lee
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I went for spray painting leg locations on the grass..... can't say it was ever very fast to align though - you should only need to drift align for azimuth if you are in the same location each time....
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Old 29-11-2007, 08:04 PM
Dennis
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Quote:
Originally Posted by Lee View Post
I went for spray painting leg locations on the grass..... can't say it was ever very fast to align though - you should only need to drift align for azimuth if you are in the same location each time....
Hey Lee

If I leave the mount out over 2 or 3 nights, I have to make very slight adjustments in both Alt and Az to touch up the polar alignment each session, using the excellent EM200 Polar Alignment ‘Scope. This amounts to perhaps 2 or 3 arc mins, and maybe points to the mount settling on/in the back lawn?

Cheers

Dennis
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