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heq5 polar finder collimation


Pete Presland

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having bought a new scope for imaging i thought it was about time i accurately set my polar alignment,beginning with the collimation of the polar scope.having spent around an hour trying to get it spot on,i finnaly settled for as good as i could get it and polar aligned with that,untill the clouds arrived :)

on reflection i can not believe how difficult and time consuming i found what i thought would be the easy part of the alignment. any body got any ideas what i am doing wrong,i adjusted the grub screws very small amounts at a time but when i rotated the mount 360 degrees the cross hairs never come back to the same point they start from.

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Take the telescope off the mount and all weights.

Sit in the garden in daylight with the mount using the tripod like a rifle tripod and look at a distant object through the polar scope such as an ariel on the roof.

Rotate the mount and adjust the 3 screws until it stays centred.

If it doesn't then something is wrong with your polar scope that is stopping it being centred.

Check the housing, loosen the screws and check for play.

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find an object like a tv arial ...point the centre of the crosshair on the polarscope to the very end of the arial......rotate your mount through 180 DEGREES......however far the centre of the crosshair moves from the end of the arial....correct it by half the distance using the little grub screws on the polarscope...move the mount back to original position...then use ALT AND AZ bolts to centre the crosshair back on the end of the arial.....rotate mount 180 DEGREES again.....if its off....correct the distance by half again...move mount back to original position....use the ALT AND AZ bolts to recentre the crosshair on the end of the arial......keep doing this until you can rotate the mount through 360 degrees and it stays on the end of the arial......remember only correct the error by half.....then recentre using alt and az.....hope this helps.

use this tutorial if need be http://www.astronomyshed.co.uk/forum/viewtopic.php?f=19&t=4006

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thanks for all the replies, i watched the link to astronomy shed yesterday afternoon before i started and his polar align as well, very good both.

i will be have another go this morning,everything does seem to be quite tight so the thing that concerns me is when i rotate the mount 360 degrees the cross hairs never come back to the same point they start from.

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I like the Astrononomyshed's modification of using those knurled thumb screws rather than grub screws. Just a word of warning, only make small adjustments.. I wound one of the grub screws too far in and had to re-assemble my polar scope and start all over again.

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Check the polar scope itself is screwed in properly...

And when you adjust, you only adjust enough to take out 1/2 the error each time - i.e. move the cross hair from where it is, to halfway to the ariel/chimney/whatever. Rotate 180 degrees and adjust again. Rotate 180 degress and adjust again..... repeat......

It can take AGES to do so patience is your friend!

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i had another go this afternoon,still don't understand why when i have turned the mount 1 full turn it does not come back to where it started,if i have made no further adjustments.

i have just order a illuminated reticule,hoping drift alignment will cut out the need for the polar scope.i might take out the scope strip it and have a look before i make any more adjustments

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To be honest, if you are mounting this as a permanent set up in your obsy (as your signature suggests) then you would be better off forgetting the polar scope alignment and opt for doing some form of drift alignment.

I spent best part of an afternoon trying to sort mine out and when I thought I got it right, found it was still out when I repeated the process on Polaris. I then used the dSLR method Imaging Tips which worked to a fashion (it's impossible to get something at 0 degree dec east or west for me)

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To be honest, if you are mounting this as a permanent set up in your obsy (as your signature suggests) then you would be better off forgetting the polar scope alignment and opt for doing some form of drift alignment.

I spent best part of an afternoon trying to sort mine out and when I thought I got it right, found it was still out when I repeated the process on Polaris. I then used the dSLR method Imaging Tips which worked to a fashion (it's impossible to get something at 0 degree dec east or west for me)

exactly what i thought malc and there a few very good looking tuttorials online to help.just need some clear skies :)

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