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question for polarisfinder

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#1 duanjacky

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Posted 22 March 2011 - 04:21 AM

is there anybody know if it is OK set a polarisfinder off the RA axis for some Mounts which should have polarisfinder.

#2 Benach

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Posted 22 March 2011 - 05:45 AM

No problems there. In fact, it is done at some mounts already. The polar axis of your mount should be parallel to the Earth's rotation axis. A few mms don't change parallelism.

#3 duanjacky

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Posted 23 March 2011 - 06:59 AM

thanks Benach, could you have some clue to help me find out those kind of mounts with pictures, thanks again

#4 Mike Clemens

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Posted 23 March 2011 - 01:12 PM

http://www.astronomy.hu/g42.htm

http://www.cloudynig...2/o/all/fpart/1



#5 duanjacky

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Posted 23 March 2011 - 08:02 PM

thanks Mike, one more question how could I paralled a polar scope axis (which is off-axis) to RA axis, is that same process to a finderscope? thank you.

#6 bluedandelion

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Posted 24 March 2011 - 12:46 PM

thanks Mike, one more question how could I paralled a polar scope axis (which is off-axis) to RA axis, is that same process to a finderscope? thank you.


I would assume that as you rotate the RA axis a distant object (I think Polaris would work really well for this) should stay centered in your polar scope. This is how reticles are positioned in polarscopes built into the RA axis.

Ajay

#7 nemo129

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Posted 24 March 2011 - 12:54 PM

thanks Mike, one more question how could I paralled a polar scope axis (which is off-axis) to RA axis, is that same process to a finderscope? thank you.


Try looking at this video . It is about an Orion polar scope, but the principle is the same.

#8 duanjacky

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Posted 24 March 2011 - 07:52 PM

thanks guys, please see picture how do i make sure the polar scope alignment is paralleled to RA axis for those kind of mount [image]http://www.astronomy.hu/g42.htm[/image]

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#9 bluedandelion

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Posted 24 March 2011 - 11:14 PM

It is difficult to see all the details of the mount, but I will take a guess. Someone else will point out any errors I might have.

Point your mount at a distant object - like a clearly identifiable point on a distant radio tower, hill whatever. If you can't do this from your location during the day, align your mount roughly north at night. Look through your polarscope and center Polaris. Lock the DEC axis and rotate the RA axis. If Polaris stays centered in your polarscope, you are done. If not use those set screws on the polarscope holder and center it again - rotate and repeat till Polaris stays put.

Ajay

#10 duanjacky

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Posted 25 March 2011 - 12:34 AM

thanks Ajay,problem is for these kind of mount with off-axis polarscope, when RA axis was rotated, a polarscope will rotate as well,you never know ploaris stays center of the polarscope by this way

#11 duanjacky

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Posted 27 March 2011 - 10:11 AM

is there anybody help me out from this confusion.

#12 bluedandelion

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Posted 27 March 2011 - 11:18 AM

I see. The other option is to do this mechanically. Here is one idea using a level.

If you can arrange for the RA axis to be made horizontal, then do so and place a level on the housing (assuming it is flat and parallel to the axis) and make it as level as you can. Then do the same with the the polarscope. This will make the two axes parallel in one orientation. You will have to do this in one more orientation preferably perpendicular to the first one. I don't have a good sense of the mount or the polarscope attachment. So this is the best I can offer at the moment.

Ajay

#13 duanjacky

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Posted 28 March 2011 - 09:19 AM

thanks Ajay






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