Quote:
Originally Posted by White Rabbit
Thanks.
Here is what I'm doing, can you tell me if I'm doing something wrong.
My location is Sydney so I set the Lat on the mount to 33 deg. Then point the mount 12deg east of magnetic south. Then I should do a three star alignment.
From what I can tell thats all I should have to do to get it roughly aligned with the SCP, or am I missing something?
I've been doing two star alignments without much luck so far. Mainly because I have a lot of trees and light poloution where I am and cant really see all the alignment stars, finding two is a push three is is really hard.
Thanks for the help.
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KG8 says: "Often the polar scope is not aligned with the mount. You can verify this by getting an object in the crosshairs (daytime) and then rotating the mount around the RAaxis. If you see the object you have centered in the hairs drift in and out you need to adjust the crosshair recticle via the 3 little grub screws on the polarscope. Be carefull !!! Overtighten them and you will smash the recticle, too loose and it will fall out. Do the job like you were collimating an sct. ie, trial and error"
Hi WB - on page 3 of this "Equipment" section of the IIS forum "Bug in Synscan 3.21 upgrade" there is further info on HEQ5 Pro's, including a bit about the reticle alignment in the polar scope that KG8 elaborates on in the preceding post. Good to know that it is something to do cautiously KG8 - I must've been lucky when I took to it! Alan Gould astually took his polar scope out to set it (see thread mentioned above.)
Just to explain WB, the reticle is the super-imposed images and central cross with rings you see in the polar scope - it has the Octans asterism (ie star pattern) in it for you to overlay onto the real Octans asterism you should see when your PS is pointing at the right spot in the sky: the reticle also has the Northern Hemisphere patterns which we ignore.
Aligning the PS reticle is what KG8 describes, scroll down in this thread to see a bit more, and remember that this is done with a fixed distant object in the daytime as your target, and you will need to set the polar axis parallel to the ground to facilitate this procedure (otherwise the PS will be aimed so high you won't be able to find any fixed object to target!)
Remember that when you set that "south" leg (the one with "N" on it!) to point geo south so that the azimuth spigot above it is also pointing south, you then have to make sure the tripod is level. I use a "bullet" level, a circular one that they use for levelling fridges etc; it fits nicely in the round hole at the top of the tripod. You will need to screw down the long bolt that holds the HEQ5 head assembly to the tripod top to fit one of these levels into the depression - but you will also have needed to do this if you are placing a compasss on top of the tripod to get your bearings; otherwise the bolt will affect the compass's reading, being steel.
Having done all this, I'm presuming you've entered your co-ordinates and time etc into the handpiece before you do the 3 star alignment: I've noticed when following this method, that the 1st and 2nd stars are quite a bit out when the scope slews to them, but the 3rd is much closer in alignment for the subsequent "alignment successful" display we hope to see.
To get a better polar alignment and subsequent "GoTo" response you should go right back to the part where I've described levelling the tripod after pointing it south (correcting for magnetic variation) and setting the altitude to approximate your latitude.
This is where you put the HEQ5 head onto the tripod top with the 2 azimuth screws wound right out and wind up that long bolt from underneath (the steel one I mentioned.) Do not overtighten this bolt to facilitate azimuth adjustment in the next step.
It's night-time, good and dark now; you've aligned your polar scope reticle in the daytime and your peering through the PS to see any stars - not forgetting to screw out the PS's eyepiece to get focus!
If you're very lucky (and I say this because I don't rely on this luck - see my posts further down in this thread) you just might see the Octans asterism (the real one, not the one etched on the reticle!) in the PS's field of view: but you would have had to have been very accurate with the compass and latitude settings to see them, owing to the narrow field of view in the PS.
This is where you use the mount's fine adjustment azimuth and altitude adjustment knobs/screws to overlay the etched reticle asterism pattern onto the real Octans star pattern. You should then have achieved fairly good polar alignment and then, if you do a 3 star alignment, should find your GoTo functioning quite well.
The red LED illuminator provided with this mount is for helping you see the PS etched reticle pattern when doing the above; but most people reckon it just floods out their view, and either flick it on and off as they adjust the alt-az to get the etched and real stars to overlap each other, or don't use the LED at all.
As alluded to, this is only one way to polar align and not my preferred method, to me it is too fiddly and chancey; I would recommend using the main scope with a very low power wide angle ep to get the centre of the FOV pointing roughly just up from sigma Octans, using the mount's az-alt fine adjusters to achieve this, and then switch to a 12.5mm illuminated reticle ep to really nail it.
From the other posts you will see that I'm a really big fan of the green laser pointers when they are accurately set up, they are accurate enough on my scopes for me to dispense with a lower power wide field ep and just go straight to the illuminated reticle - I obviously do my initial alt-az fine adjustments after rough set-up by getting my laser beam to hit a spot just above sigma Octans!
Don't forget to finally tighten that long steel bolt right up to "lock" the mount and head!
Cheers, Darryl.
Thanks for the Tip Darryl and thanks Terry also for the verbose replies.
