How critical is the home position?

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NikkiT
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How critical is the home position?

#1

Post by NikkiT »


I have just bought myself a Skywatcher EQM35 pro mount.
This is my first serious eq mount and my first goto mount.
Could anybody advise me as to how accurate the leveling of the mount and setting the home position needs to be?
Thanks, Nikki
Skywatcher ED80, Skywatcher EQM35 pro, Canon eos100d, second hand 10x50 binoculars (unknown brand, but they work great!)
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JayTee United States of America
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Re: How critical is the home position?

#2

Post by JayTee »


The only thing being perfectly level does for you is to get your scope pointing close to the first star you pick for your goto alignment, but this is not a guarantee. Most of us spend about 2-3 minutes leveling then say "that's close enough." As to your home position accuracy, the same thing applies, it helps the scope slew more accurately to your first alignment star. After you have a successful alignment the mount just doesn't care if you started out level or not. If you are already familiar with the night sky then don't sweat getting it perfect.

Cheers,
JT
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
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yobbo89 Australia
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Re: How critical is the home position?

#3

Post by yobbo89 »


It depends on your setup,i use plate solving so alignment is almost never done :D

as for leveling with the bubble on your mount, really it's only there to get a good balance on the surface your mount is sitting on , you don't want your tripod tipping over, error in leveling is corrected when polar aligning.
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
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extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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KathyNS Canada
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Re: How critical is the home position?

#4

Post by KathyNS »


Leveling the mount is not important. It makes finding Polaris in the polar scope easier, that's all. The mount could be totally askew and you would still be able to polar align it, with a bit more effort.

The home position is important for your goto alignment. Again, it makes it easier, but the goto will work well if it is moderately close and you centre the stars well. If the home position is not accurate, the slew to the first alignment star will be out by an amount equal to the error in the home position. If your home position is ten degrees out, the slew will end up ten degrees away from the first alignment star. Once you correct that error by centring the star, the alignment will get progressively more accurate. Once you successfully complete the alignment, the inaccurate home position will be forgotten.

It is not difficult to establish an accurate home position, so it is good practice to do so every time. This hobby relies on accuracy, so it is a good habit to get into.
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NikkiT
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Re: How critical is the home position?

#5

Post by NikkiT »


Thanks for the advice.
I have set up my mount indoors this afternoon and used a spirit level on the ra and dec axis, then flipped each 90 degrees and marked the mount.
Hopefully this should give me a reasonable home position to start from.
Skywatcher ED80, Skywatcher EQM35 pro, Canon eos100d, second hand 10x50 binoculars (unknown brand, but they work great!)
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