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Old 20-03-2013, 01:55 PM
Star Hunter
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Star Hunter is offline
 
Join Date: Dec 2011
Location: Ellesmere, Qld
Posts: 210
Quote:
Originally Posted by HunterGeo View Post
I have been having no end of problems achieving a decent polar alignment of my HEQ5 mount. I've had it for three months and I still haven't got it to point anywhere near what I want to be imaging. Can somebody please help figure out what I am stuffing up?

My ideal process would be as follows:
1. Point northern leg of tripod toward SCP. Make sure tripod is level in all directions. Attach accessory tray, mount, telescope, etc.
2. Go through three-star alignment process. This typically is done with Sirius, Achernar and Alpha Centauri.
3. Hand controller then reports error margins in elevation and azimuth.
4. I manually correct the errors using the azimuth and elevation control knobs.
5. I do a second three-star alignment with the same stars to get new error margins and make any corrections as needed until within acceptable alignment (for me, ideally less than a minute in both elevation and azimuth - my effective focal length when imaging is 5400mm once I attach the barlow, teleconverter and camera).

(When doing the alignment, I'm just using a standard 1.25" illuminated reticule eyepiece, so the focal length during alignment is effectively 600mm - i.e. just the telescope).


Instead, what happened last night is a good example of what typically happens...

1. First three-star alignment reports 22 degrees out in azimuth and ten minutes out in elevation (don't know how elevation was so precise on initial setup!).
2. Was happy with elevation, so left that alone. Moved the azimuth to the west as far as Azimuth control knobs would go (I am using the longer upgrade bolts for Az, not the stock-standard ones as I found they were useless). I could only get 15 turns of the knobs done, so I wasn't expecting azimuth to be close enough... but for the purposes of testing the mount I wasn't going to bother packing it all up and moving the tripod.
3. I then did a second three-star alignment, but the error margins changed unexpectedly:
Azimuth moved in the correct direction (now only 11 degrees out in the same direction). BUT

The elevation was then suddenly out by 4 degrees!


Is it normal for the mount to have moved in elevation despite my only changing the azimuth knobs?



Another story from last week, I was trying my first-ever drift alignment.
I started with elevation at 44deg.

When doing the first star (to align the elevation), I managed to get it so that there was no drift in five minutes. This was at elevation of 20deg! (I'm in Melbourne!)
But as it was a practice run, I decided to see how good I could get it, so I moved the elevation down three more degrees, and suddenly the star drifted across the entire eyepiece in 30 seconds! What the?!


So as you can perhaps understand, I have been banging my head against the wall trying to figure this all out. Can anyone please advise where I am going wrong?

Thanks in advance.

Mate, no equatorial mount can just be plopped down and expect to work. You have to set it up first. Go to this link http://www.southern-astro.com.au/php...talignment.php and perhaps join your local astro club. One comes to mind here... http://asv.org.au/

JB
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