Jump to content

stargazine_ep34_banner.thumb.jpg.28dd32d9305c7de9b6591e6bf6600b27.jpg

Polar alignment questions (Newbie alert!!)


Recommended Posts

I am confused.

I have bought a HEQ5 and I am trying hard to understand polar alignment and setting circles.

My trials so far have been -

Level tripod and roughly align North - set to match my Latitude 56.26 degrees North - hey presto - Polaris appears in polar finderscope and with a bit of knob twiddling it is roughly centred.

This is where the wheels fall off the wagon. (Although I believe that this is close enough for decent visual observation ??)

If I use Polarfinder.exe or click on the polar time box in EQMOD I get a diagram that shows where on the polar circle in the polar finder the star should be placed and both methods give the same result.

I could just knob twiddle until the star is in the right place on the polar circle in the polarfinder - would that be good enough ????

The bit that is totally confusing me is the setting circles. I put the scope in park position (with the weight bar pointing straight down) and zero the RA circle. My understanding is that if I now turn in RA until the circle displays the polartime value on the bottom row of numbers then the polarscope reticule should put the polaris dot in the corrcet place ?????

It doesnt.

I am sure I am doing something fundamentally wrong but if I had hair I would be ripping it out right now !!!!

Any help/guidance most welcome (pardon the pun!!)

Link to post
Share on other sites

From memory when i had the HEQ5, the polarscope was etched with a couple of constellations, one being Ursa Major. You just rotated the RA until the etching in the polar scope matched the actual position of Ursa Major in the sky. Then place Polaris in the small offset circle. Have they changed it now, are there no etchings?

Edited by russ
Link to post
Share on other sites

If I use Polarfinder.exe or click on the polar time box in EQMOD I get a diagram that shows where on the polar circle in the polar finder the star should be placed and both methods give the same result.

I could just knob twiddle until the star is in the right place on the polar circle in the polarfinder - would that be good enough ????

Good enough for visual certainly.

If you're using EQMOD anyway you might as well use it's polarscope alignment routine to put get the small polaris circle in the correct place and then just know twiddle until polaris is in the circle.

Chris

Link to post
Share on other sites

I always just center polaris on the crosshair, then adjust the altitude till Polaris is at the bottom of the larger circle, set this to zero on the setting circle, find out your adjustment for the current position of Polaris, rotate RA till you are roughly at this adjustment, this moves the star aligning circle in the polar scope so you can adjust alt/az bolts to center Polaris on this smaller circle.

Helps me to dim the polar scope illumination to about 4%

After this you can use the Polar alignment routine to fine tune it, or get ALignmaster (awesome and cheap but slightly restricted on alignment star pairs) or do a drift alignment.

I always thought drift alignment would be beyond my skills but it is surprisingly easy. I tried it for the first time the other night and I got nearly 10 minutes unguided!!!

cheers and good luck

Chris

Link to post
Share on other sites

For visual, I just line up Polaris in the direction of Kochab. Then adjust RA and dec until Polaris is on the etched circle . This holds tracking at x200. Can't be fussed with trials of dials in the dark!

Nick.

  • Like 1
Link to post
Share on other sites

I use Polarfinder to determine where Polaris should be on the circle in the polar scope... say 3 o'clock for example.... then adjust mount alt and az bolts to put Polaris at that spot.

I don't bother with getting the little circle in the right place... Polaris disappears behind the line on the graticule when on the circle...good enough for me.

I couldn't get my head round all the setting circle business!

Link to post
Share on other sites

From memory when i had the HEQ5, the polarscope was etched with a couple of constellations, one being Ursa Major. You just rotated the RA until the etching in the polar scope matched the actual position of Ursa Major in the sky. Then place Polaris in the small offset circle. Have they changed it now, are there no etchings?

You are correct, there are two constellations etched on the polarscope, Ursa major and Cassiopeiae.

Link to post
Share on other sites

Hi as already said your current procedure is more than good enough for visual as to the second point about the error in its position remember that stellarium etc often shows a non inverted view the polarcope inverts, the other thing is that the hour position has two sets of marks one clockwise the other anti make sure you are using the right one.

The polar finder software gives you a good idea as to the position of polaris but i find it doesnt have enough resolution.

Alan

Link to post
Share on other sites

just one other thing to make sure is that the reticule is centred in the polarscope. This is done by centering Polaris on the crosshairs using the mounts latitude and azimuth controls, then rotating the mount roughly 180 degrees in RA and seeing if Polaris has drifted from the centre of the crosshairs. If it has the reticule isn't centred and needs adjusting via the three tiny grubscrews. I did mine in very small steps to avoid having the reticule fall out of its cell , (about an eighth of a turn each time), slackening the screw on one side and taking up the slack with the other screws, to move Polaris HALF WAY back to the centre of the crosshairs. Then rotate mount back to original position in RA and recentre Polaris, this time using the mounts controls as at the start. The sequence is repeated until Polaris stays at the centre of the crosshairs regardless of RA.

  • Like 1
Link to post
Share on other sites

That it pretty much it Tony but you either have the knack at doing it or you don't, just like me.

I've given up trying now because every time I try it, I loose the will to live. Been trying for 5 months now.

Good luck.

Edited by hobsey
Link to post
Share on other sites

Oh yeah, forgot that step. Fairly crucial!!! I think I did mine in daylight by finding a far away point, aligning the polar scope cross hair then rotating it. If I remember rightly if you rotate it and it moves off the target, you have to move the polarscope in the direction of movement. You're centered when the cross hair stays on the point when rotated.

there's a good video on youtube somewhere. Probably astronomy shed.

Good luck mate.

Link to post
Share on other sites

The Polar scope is one the hardest things to get right when you first start. The post Tonys and m37 are extremely important if you want to combat drift alignment - i.e. using Stellarium or CdC can quickly get out of sync if you don't centre the reticule.

Also useful to know is the position of Polaris on Polar scope circle. You will easily find this by using PolarFinder, which is an app for a Smart Phone.

Link to post
Share on other sites

Oh yeah, forgot that step. Fairly crucial!!! I think I did mine in daylight by finding a far away point, aligning the polar scope cross hair then rotating it. If I remember rightly if you rotate it and it moves off the target, you have to move the polarscope in the direction of movement. You're centered when the cross hair stays on the point when rotated.

there's a good video on youtube somewhere. Probably astronomy shed.

Good luck mate.

That's right. I'd read somewhere that you had to make the adjustment in the opposite direction to the drift, but found in practice it is as you say eg if Polaris drifts upward in the view on RA axis rotation, the topmost grub screw is the one to loosen a little, then take up the slack with the other two, which moves the reticule ( which is simply overlaying the image) towards Polaris. I have to say I found it needed a lot of patience, the worst part being trying to repeatedly locate the hex key in the tiny grub screws.

Link to post
Share on other sites

When you say drift, you're not drift aligning to get the polar scope centered are you? The grub screws are for this and not for drift alignment. To align the polar scope use the grub screws to centre the solar scope in the daytime. Drift alignment is to align the mount not the scope. Complicated to get this stuff sorted at first but you'll get there!

Link to post
Share on other sites

When you say drift, you're not drift aligning to get the polar scope centered are you? The grub screws are for this and not for drift alignment. To align the polar scope use the grub screws to centre the solar scope in the daytime. Drift alignment is to align the mount not the scope. Complicated to get this stuff sorted at first but you'll get there!

Sorry - drift wasn't the best word. I mean the apparent shift of Polaris away from the centre of the crosshairs when we rotate the mount in RA through 180 degrees. I was brave or foolish enough to do my reticule centering at night, hence my difficulty with the hex key ! I do use star drift alignment sometimes with my Tal-2 mount, which doesn't have such luxuries as a polar scope.

Link to post
Share on other sites

I've been told to use Kropster's method. I've yet to try it with this bloomin' rain!

I'm at work so can't post YouTube vid links, but, as m47 said, do a search on YouTube for astronomyshed and his polar alignment / mount set-up vids. There are 4 I think.

I too have had awful trouble aligning the reticule. I managed it fine the first time years ago then, just recently, I did it again and was in tears of frustration! Be prepared! I use Astrobaby's alignment tutorial. I used to use her polar alignment tutorial which has been OK but I needed something better, so Kropster's method is next on my agenda and supposedly very good - and easy! Do ensure your mount is accurately at park. Astronomyshed's tutorials include how to do that. 

Alexxx

Edited by Astrosurf
Link to post
Share on other sites
...

The bit that is totally confusing me is the setting circles. I put the scope in park position (with the weight bar pointing straight down) and zero the RA circle. My understanding is that if I now turn in RA until the circle displays the polartime value on the bottom row of numbers then the polarscope reticule should put the polaris dot in the corrcet place ?????

It doesnt.

I am sure I am doing something fundamentally wrong but if I had hair I would be ripping it out right now !!!!

Any help/guidance most welcome (pardon the pun!!)

If your HEQ5 is like mine the RA scale is loose and does not turn consistently with the RA and can drag. So a 180 turn in RA is not always a 180 turn on the scale.

Not sure if mine is faulty or badly adjusted but since I don't bother with polarscopes any more it's a moot point for me. I use the post alignment built into the handset routine to polar align - my HEQ5 is pier mounted so not a hassle now.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.