Finally Polar alignment success... but

FarmerBen · #1 09-08-2008, 06:53 PM

After a bit of hit and miss I finally managed to get a southern polar alignment with no significant drift over 5 mins. YAY! I think I have a few more grey hairs, but the milburn wedge I'm using is rather fantastic.

However, I'm becoming frustrated with my LX200 pointing accuracy. At the moment, every object I point at is the same distance out of centre, which is far enough out that the "GOTO" search can't find it and the object is almost out of the field of view of the finder scope. This is occuring in both polar and Alt/Az setup and is the same amount in either setup.

I'm still coming to grips with the scope so was wondering if anyone has some tips for "correcting" the accuracy? Can I perform the training in polar mode and is this what is required?

Thanks in advance,
Ben.

beren · #2 09-08-2008, 08:02 PM

Gday Ben from memory training the drives of your LX200 should improve your GOTO pointing accuracy. Hopefully you have the manual to describe the procedure, once done I think you will notice a difference, you should do this after a few months. I'd suggest doing it in Alt/AZ mode with a terrestrial target, read the manual and follow the instructions the autostar pad gives and you should be up and running no worries {congrats on the milburn wedge to}. You may have noticed the other "calibrating sensor" training mode from memory that improves your initial alignment star pointing.

astroturf (Bryan) · #3 09-08-2008, 08:07 PM

G'day Ben

I experienced that very same problem with my LX90 & Superwedge & was advised that drive training in polar mode was essential for correct pointing

I've since carried out drive training, now everthing is reasonably centred in the FOV using GOTO
"Calibrate Sensors" is not possible or necessary in polar mode in case you're wondering

Good luck
Bryan

GrampianStars (Rob) · #4 09-08-2008, 08:19 PM

(1) Train drive on a Terrestrial object
(2) 2 Star allign
(3)

FarmerBen · #5 09-08-2008, 08:32 PM

Quote:

Originally Posted by GrampianStars

(1) Train drive on a Terrestrial object
(2) 2 Star allign
(3)

Thanks, will give it a shot tomorrow night.

aworley (Alex) · #6 10-08-2008, 07:00 AM

I trained my drives using this spreadsheet - it takes a while, but I havent had any problems since doing it....look for the spreadsheet modified by Niall Saunders - ......

http://www.weasner.com/etx/autostar/opt-train.html

Alex

GrampianStars (Rob) · #7 10-08-2008, 07:14 AM

G'day Ben
Note :
POLAR" mode is OK for drive training - NO need to ruin your drift allignment
"calibrating sensors" ignore this as it doesn't apply for polar mounted LX scope

Quote:

Originally Posted by beren

.....training the drives of your LX200 should improve your GOTO pointing accuracy. Hopefully you have the manual to describe the procedure, once done I think you will notice a difference, you should do this after a few months,.... with a terrestrial target,.. you should be up and running no worries {congrats on the milburn wedge too}. You may have noticed the other "calibrating sensor".......

AndrewJ · #8 10-08-2008, 09:30 AM

Gday Ben

What firmware???
How did you align??
If current firmware ( 42g ) and you did a Polar two star align
there is a possible bug, especially if your first star is off.
Normally the bug manifests as the first star being off by say 1/2 to 3/4 of a finder normally to the left. After aligning, you get a successful align but the warnings say you are a long way off the pole, and gotos are crud.

If the above is the case, try a polar two star, and if the first star is off by more than 1/2 an EP ( note! EP NOT Finder )
then release the clutches and manually centre the first star best you can in the EP. You can get very close. Then lock the clutches and fine centre
Then accept and go to the second star as per normal.

You should get much better results

Andrew

FarmerBen · #9 10-08-2008, 02:53 PM

Quote:

Originally Posted by AndrewJ

Gday Ben

What firmware???
How did you align??
If current firmware ( 42g ) and you did a Polar two star align
there is a possible bug, especially if your first star is off.
Normally the bug manifests as the first star being off by say 1/2 to 3/4 of a finder normally to the left. After aligning, you get a successful align but the warnings say you are a long way off the pole, and gotos are crud.

If the above is the case, try a polar two star, and if the first star is off by more than 1/2 an EP ( note! EP NOT Finder )
then release the clutches and manually centre the first star best you can in the EP. You can get very close. Then lock the clutches and fine centre
Then accept and go to the second star as per normal.

You should get much better results

Andrew

Thanks Andrew, and everyone else. This could be what I'm experiencing. I'm about to put some pavers down under the tripod legs so I'll check this out at the same time.
Cheers,
Ben.

FarmerBen · #10 10-08-2008, 04:49 PM

Quote:

Originally Posted by AndrewJ

Gday Ben

What firmware???
How did you align??
If current firmware ( 42g ) and you did a Polar two star align
there is a possible bug, especially if your first star is off.
Normally the bug manifests as the first star being off by say 1/2 to 3/4 of a finder normally to the left. After aligning, you get a successful align but the warnings say you are a long way off the pole, and gotos are crud.

If the above is the case, try a polar two star, and if the first star is off by more than 1/2 an EP ( note! EP NOT Finder )
then release the clutches and manually centre the first star best you can in the EP. You can get very close. Then lock the clutches and fine centre
Then accept and go to the second star as per normal.

You should get much better results

Andrew

Ok, a bit more information...

I have the 4.2g firmware version and did a 2 star polar alignment using the direction in Chris James' article here in the beginners section. I have set the scope to get a GPS fix at startup.

The first start in the 2 star alignment is not even in the FOV for the finder let alone the EP.

I've had to move the scope to bury some pavers for the tripod to sit on. I'll be trying another polar alignment tonight. I hope I can find that damed Sigma Octanis... it seems to move all over the sky for me

AndrewJ · #11 10-08-2008, 08:34 PM

Gday Ben

A Polar two star doesnt use Sigma Octans

so dont worry about trying to find it
There are many ways to align a Meade LX200GPS
( and more ways to cheat )

If you "know" you are well polar aligned
( ie you have drift aligned ), then just do a polar one star align
When it says centre Sig Oct, just hit enter and then centre the second star

If you do do a polar two star, you MUST manually centre the first star by declutching ( not use the HBx ), or she'll turn to custard.

Andrew

FarmerBen · #12 10-08-2008, 09:07 PM

Quote:

Originally Posted by AndrewJ

Gday Ben

A Polar two star doesnt use Sigma Octans

so dont worry about trying to find it
There are many ways to align a Meade LX200GPS
( and more ways to cheat )

If you "know" you are well polar aligned
( ie you have drift aligned ), then just do a polar one star align
When it says centre Sig Oct, just hit enter and then centre the second star

If you do do a polar two star, you MUST manually centre the first star by declutching ( not use the HBx ), or she'll turn to custard.

Andrew

Ah ok, I'll give those a shot. I didn't realise I had to declutch on a two star. The two star I mentioned previously was based on the Polar alignment method, not the Autostar align program.

I've parked the scope and given up for the night. Going from binoculars, to finder scope, to EP is doing my head in at the moment. Plus having to contort to look through the finder is doing amazing things to my spine which I'm sure I'll pay for later on

. I ran the training this afternoon and seemed to make a fair amount of difference. What I wouldn't give for a little green cross in the sky right on the SCP

.

AndrewJ · #13 11-08-2008, 08:36 AM

Gday Ben

Quote:

I didn't realise I had to declutch on a two star.

Normally you shouldn't have to.

There has been a lot of testing of this bug, as there are several variations on how it appears. ( Ie parking affects it too )
If you are doing a "clean" Polar two star in 42g, it appears the code is semi broken.
If you do a one star, all is OK, just do as per the book
If you do a two star, use the clutches to centre the first star only

You shouldn't have to do it, but it appears to be the best workaround, if the first star is off.

Andrew

[1ponders] (Paul) · #14 11-08-2008, 01:44 PM

Hi Ben.

If you are up for a trip to the Mapleton Observatory this Sunday evening I can run through the process with you if you still have problems. I've used the declutch method a few times now and it works a treat. I'll be there from around dark to about 7:30 - 8:00. We do telescope workshops the third sunday of each month.