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jonnydreads

Wedge problem / polar alignment

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Posted (edited)

Hi guys.

Im currently indoors trying out a practice polar alignment with a wedge I made yesterday. I'm pulling my hair out.. as I'm turning the azimuth left of right, it only goes so far.... then it stops. I've never noticed this before when the azimuth is level on the alt/az mount..... is this normal? The drawing in my manual is rubbish, I don't know if I have it facing the right way or not.... ?

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Edited by jonnydreads

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You should have the slope of the wedge facing north and the scope pointing south at 0 dec'  to start.

Have you set the hand controller to Equatorial ?

Dave

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33 minutes ago, Davey-T said:

You should have the slope of the wedge facing north and the scope pointing south at 0 dec'  to start.

Have you set the hand controller to Equatorial ?

Dave

Hi no I haven't set it to equatorial on the handset as it doesn't tell me too in the manual, I will look for that.

The telescope itself is now set to 0 Dec and virtually facing south. The sloping board is now facing towards north.

As it slewed to go to a star on north equatorial alignment mode it nearly crashed into the wedge but I stopped it in time. Is this because it's not set to equatorial mode or something 

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20190310_164429.jpg

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Posted (edited)

Something was catching and stopping the motor half way round.... still not practiced alignment 

So much trial and error! God knows what william herschels life must have been like,  I have everything virtually on a plate and I'm still struggling ?

Edited by jonnydreads

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Scope is pointing South but is upside down.

That might be correct, for instance the Meade LX200GPS on wedge starts pointing north and upside down.

Michael 

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Posted (edited)

Scope shouldn't be upside down, maybe you need to rotate the base to get it the right way up.

Dave

Edited by Davey-T
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Posted (edited)

Don't follow the instructions printed in older SE manuals that describe a 'Wedge Align' if using a Nexstar + HC.  The process has been replaced by an ASPA.

You need the revised instructions for an 'All Star Polar Align' (ASPA) for which your start position is with OTA aimed South at its index marks; mount leaning North set at your latitude if using a Celestron wedge.  I wonder, is that your problem. Is your home made "latitude scale" correctly calibrated? Or are you simply trying to target Polaris using a redundant 'Wedge Align'? An ASPA permits a polar alignment even where Polaris is not visible. 

Assuming your home made wedge replicates a Celestron wedge and you can roughly set it to your correct latitude you then need to perform an EqNorth Align (follow instructions in HC). Then perform a Polar Align. Then when mount and wedge are physically polar aligned (here you twiddle knobs with Celestron wedge to remove the "Polar Alignment Error"), reset OTA to its start position, recycle power, and conclude with a further EQNorth Align.

I think crucial to success will be how you calibrate your angle to set latitude. I am not sure how you do that with a home made wedge. Even with a proper Celestron wedge I found the margins for error quite slim (I now use Hyperstar, as I became so frustrated with my wedge, albeit I mastered it).

P.s. Your OTA is upside down. Your mount needs to be rotated 180° and the OTA correctly affixed.

 

Edited by noah4x4
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Hi thanks!  The wedge does have provisions for adjustments on my wedge although how accurate they are I'm yet to see as I haven't got that far yet. 

I used a protractor to measure the angle of latitude for myself which I drew lines on the inside of my wedge for. How accurate that is going to be is certainly the question. I suppose trial and error again.

ThanKyou for replies 

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It will be accurate enough for camera and lens I think. But trial and error for your telescope on how accurate it is. The long focal length magnifies any issues. 

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1 hour ago, happy-kat said:

It will be accurate enough for camera and lens I think. But trial and error for your telescope on how accurate it is. The long focal length magnifies any issues. 

I have fitted a focal reducer f/6.3 hopefully this will help 

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This reminds me of my old mead LX200 10" gps telescope. Making fine adjustments to polar align the heavy metal wedge etc was a nightmare.

Not much fun in the cold and dark of an observatory.

Steve Johnston 

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Could someone tell me if this is the correct way to measure the angle of degrees for my wedge....do I measure it from 0 degrees  (horizontal) like in the picture,  or should it be measured from 90 degrees  (vertical)??  I am 51 degrees from my location.

 

20190315_160114.jpg

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Posted (edited)

From 0 to 51° this should then mean the angle of the wedge is 51°and positioned at the same angle of Polaris for your latitude. Being exact you would use the North celestial pole.

0 being horizontal

Edited by happy-kat
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7 minutes ago, happy-kat said:

From 0 to 51° this should then mean the angle of the wedge is 51°and positioned at the same angle of Polaris for your latitude. Being exact you would use the North celestial pole.

So basically how I have it set up on the picture? I do have a few adjusters on the wedge... will see... the hardest part is living in England. Once a month I can see polaris ?

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ok, I have since figured out that it is 51 degrees from 90 degrees, so it should be set 39 degrees from 0 degrees as I'm already at 51 degrees at my latitude

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