Polar Alignment & Mount Puzzle ?

[Newforestgimp]

Hi All,

Quick question on that rarely mentioned conundrum Polar Alignment 😉
I have a SW EQM-35 Mount and I'm polar aligning fairly well and fairly consistently, but feel it could be more luck than judgement. I'm using a consistent method of positioning tripod to fixed points on my Patio, I then adjust position using a magnetic compass not the iPhone as it swears north is West sometimes ! All good so far and results in a minor tweaking each night to get polaris on the dial but its relying on my ability to see by eye if the polar clock is perpendicular.

The vagueness in what I'm doing is what I don't understand and need some help with, I have to release the clutch on the mount & pivot the axis slightly so the polar scope clock is pointing vertical ? Why isn't the clock/polar scope vertical anyway ? can this be adjusted ? I assume its something to do with the dial and markings on the mount at the eyepiece end of the polar scope. Is there an easy explanation of these markings and how to use them ?

Any layman explanation appreciated.

Andy

[Robindonne]

They just throw that piece of glas in the polarscope and you can do some un-clutching and twisting yourself to get the clock in good position.  Its normal.  But you can remove te polarscope and carefully remove the front(eye) side, ánd the 3 hex calibration screws on the front/side to rotate the glass with the map.   I would mark the 12 hour position on the polarscope before you unscrew it from the mount.  
 

As soon as you have the polarscope removed from the mount to adjust the glass, you need that 12 hour mark to align both.  

[Jamgood]

Both mounts I've had have been the same. It makes no difference to alignment though. I just rotate the RA and do what's needed, then return the scope to the home position.

The reticle could be upside down and back to front, it doesn't matter. It's only a reference circle. As long as Polaris stays on that line when you rotate, all good.

[Newforestgimp]

Thank you, its the arbitrary movement to have the clock face pointing straight up thats bugging me most at the moment, i release the clutch, rotate until 6 at bottom 12 at top, it all just seems a bit imprecise when the goal is to get within seconds of proper alignment.

I'm wondering whether i need a plumb line to make sure clock is pointing straight up and then marking the mount ? I really dont want to remove the polar scope if i can help it.

I'm guiding so polar alignment isn't the be all and end all, it just bugs me all this precision but relies upon checking something by eye ?

Andy

[Jamgood]

It bugged me at first also, but after a few times doing it I passed caring. A circle is still a circle regardless of orientation. 

I just eyeball it. If you want to make sure you're good, rotate the RA 180° and check that Polaris is still on the line. As long as the reticle is calibrated it's not a problem.

[Jiggy 67]

51 minutes ago, Newforestgimp said:

Thank you, its the arbitrary movement to have the clock face pointing straight up thats bugging me most at the moment, i release the clutch, rotate until 6 at bottom 12 at top, it all just seems a bit imprecise when the goal is to get within seconds of proper alignment.

I'm wondering whether i need a plumb line to make sure clock is pointing straight up and then marking the mount ? I really dont want to remove the polar scope if i can help it.

I'm guiding so polar alignment isn't the be all and end all, it just bugs me all this precision but relies upon checking something by eye ?

Andy

To make your polar scope accurate, try the following but the mount MUST be level for this.

place Polaris at the centre of the polar scope reticle 

Now, using ALT BOLTS ONLY adjust the altitude until Polaris is at the top of the reticle circle 

Now rotate the axis in RA until the 12 o’clock position of the polar scope reticle is sat on Polaris. Your polar scope is now calibrated 

Carry out PA as normal

Return to home position 

Hope that helps

[Newforestgimp]

11 minutes ago, Jiggy 67 said:

To make your polar scope accurate, try the following but the mount MUST be level for this.

place Polaris at the centre of the polar scope reticle 

Now, using ALT BOLTS ONLY adjust the altitude until Polaris is at the top of the reticle circle 

Now rotate the axis in RA until the 12 o’clock position of the polar scope reticle is sat on Polaris. Your polar scope is now calibrated 

Carry out PA as normal

Return to home position 

Hope that helps

Of Course !!!!!

Cant believe i didn't think of that DOH!, i could do that during the day and mark the mount to always get it perpendicular quickly.

Thank You

[Jiggy 67]

59 minutes ago, Newforestgimp said:

Of Course !!!!!

Cant believe i didn't think of that DOH!, i could do that during the day and mark the mount to always get it perpendicular quickly.

Thank You

Well you would have to do it ai night to see Polaris (though I suppose you could use any far off fixed point, bit awkward through a polar scope though) but you’re right, if you mark the mount up, you may only have to do it once 

Edited February 12, 2021 by Jiggy 67

[StevieDvd]

If you are going to rely on your polarscope for PA then you must get it aligned properly first. Easier in daylight using a distant target, lampost or tv aerial etc.  Once this set the rest is gets a lot simpler.

[theropod]

8 hours ago, Newforestgimp said:

Thank you, its the arbitrary movement to have the clock face pointing straight up thats bugging me most at the moment, i release the clutch, rotate until 6 at bottom 12 at top, it all just seems a bit imprecise when the goal is to get within seconds of proper alignment.

I'm wondering whether i need a plumb line to make sure clock is pointing straight up and then marking the mount ? I really dont want to remove the polar scope if i can help it.

I'm guiding so polar alignment isn't the be all and end all, it just bugs me all this precision but relies upon checking something by eye ?

Andy

I have exact same mount, and the polar scope reticle was out of whack to me, so I fixed it. The three grub screws that lock down the reticle only need a little loosening and the reticle will free up. I set mine on a distant lone pine on a ridge a few miles away. I also pointed the reticle with the 12 o’clock straight up. I used the edge of my patio door frame as a guide to set the vertical bar of the reticle to plumb. If you do move the reticle be VERY careful about those grub screws. They are tiny and so easy to drop if backed out of the threads too much. I would also take care when tightening them back as to not strip the threads and or not crack the reticle. So, I say that if the reticle bothers you it’s no biggie to fix. It took me longer to modify an Allen key with a whet stone to fit the tiny little grub screws than to fix the issue. They’re supposed to be 2.5mm, but mine were a touch small.

[Robindonne]

2 hours ago, theropod said:

I have exact same mount, and the polar scope reticle was out of whack to me, so I fixed it. The three grub screws that lock down the reticle only need a little loosening and the reticle will free up. I set mine on a distant lone pine on a ridge a few miles away. I also pointed the reticle with the 12 o’clock straight up. I used the edge of my patio door frame as a guide to set the vertical bar of the reticle to plumb. If you do move the reticle be VERY careful about those grub screws. They are tiny and so easy to drop if backed out of the threads too much. I would also take care when tightening them back as to not strip the threads and or not crack the reticle. So, I say that if the reticle bothers you it’s no biggie to fix. It took me longer to modify an Allen key with a whet stone to fit the tiny little grub screws than to fix the issue. They’re supposed to be 2.5mm, but mine were a touch small.

And dont forget to calibrate after loosening the 3 screws.   Check tonight if a star at crosshair center is still as crosshair center when you turn the ra axis.  Orherwise adjust it with these 3 hex screws you loosened during that reticle job.  

[theropod]

Yes, and I used that distant lone pine to make sure the crosshairs stayed true with mount rotation. 

[iapa]

Video covering reticule alignment on polarscope

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjMwp27n7LvAhWoUBUIHYfqD8oQwqsBMAZ6BAg5EAM&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DQf78QUpZj4s&usg=AOvVaw0xUtgUr_zop3FoyPoi6yQa

 

[Deadlake]

There is also this thread here as well: