How acurate is your "goto" ?

[toryglen-boy]

I have recently aquired a HEQ5 Pro mount in very good condition from another forum member (thanks Daniel you where very helpful!) i no the polar alignment isnt exact, but for observational use its pretty good, but i am finding out that the "goto" on it is woefully inaccurate, i know its probably caused by me messing around with the mount, and i know there is nothing wrong with the equipment, it just doesnt seem that acurate at all !!

I am using an Orion ED80 with a Meade 26mm plossl, the scope is only F7 (F7.5?) so it should be a wide-ish FOV, but its usually out by quite a bit

Can anyone recommend any tips for getting the best out of the HEQ5 Pro mount?

thanks

:thumbsup:

[madwayne]

Hi Duncan

Are you doing a three star alignment? And making sure one of three is on the opposite side of the meridian to the other two? Your first alignment star will usually be well off (outside the FOV your finder, or it was when I tried it with my EQ6) but the next two should be pretty close. The aim is to draw a big triangle around the part of the sky your are viewing/imaging - if you knew this my apologies for pointing it out.

Also, you bought the mount from someone on the forum, is he in Canberra by any chance or do you need to adjust the lattitude on the side of the mount?

I've made these suggestions on the assumption you are entering lattitude and longtitude correctly as well as the date in the correct format on the hand controller.

That's all for now please report back :).

Wayne

[toryglen-boy]

Hi Wayne

Yeah i knew what it was trying to do, and yeah the first star is usually way out, and the other two, not so bad. I got the mount, leveled it (checked all over with a spirit level) and set the angle of the tilt with a digital inclinometer so i know its pretty good. Alignment has been set with a digital compass pointing to the pole rather than magnetic, although i have a compass and have worked out the amount of degrees its out from the pole, and i have covered as much as i can.

I suppose drift alligning of the pole would help, to get it as accurate as poss.

does anyone have any general advice on this mount?

thanks

[Terry B]

My EQ6 with the hand controller would be within 20arcmins with any slew. With the EQMOD it is within 10arcmins always.
Polar alignment needs to be reasonable.
Can you use the polar scope?
If you can get it close with your inclinometer and compas you should be able to find the 4star asterism that is used on the polar scope. This is plenty accurate for visual use.

[mozzie]

different scope and setup but my meade 2 star align the first star is within the 2 deg ring on my telrad and the second is in the eyepiece it tracks perfectly all night and centre of eyepiece so they are very accurate make shore the tripod legs are tight and on solid ground any movement and it all fails you may have to train your drives and make shore the backlash is correct this can cause it to drift it works fine but they can easliy go pear shaped if something is not right since ive permently piered mine its never been a prob
mozzie

[toryglen-boy]

Due to trees, and buildings the pole is invisible from my location 365 days a year

i am sure with perserverance, i will get on top of it

[Robert9]

With my Nexstar I can get an object into the field of my 8mm Hyperion (mags = 180 x) from a swing of more than 180 degrees. I found a lot depended on backlash compensation and during the inital alignment, approaching the alignment stars in the same directions (altaz) as the goto.

[gmbfilter]

I have a HEQ5Pro
I set it to magnetic South with a compass
Level by eye, almost always do only 2 star align.Then it's "up up and away"
Its distance to initial alignment stars seems random and I don't worry anymore.
I would waste heaps of time fussing about with my initial polar alignment.
Drift alignment is a different issue.
Most errors are me aligning on wrong star.
I take the first 2 stars that come up in menu (unless they are behind my Hill)

[toryglen-boy]

Thanks for that, but how accurate is the goto?

:shrug:

[pmrid]

I noted that you aligned on magnetic south. Whoops! You need true south of course. And depending where you are the divergence can be quite significant. I'm in an area of 11 degree variation. You shoulod correct that immediately and then go back and do your go-to system's alignments.
Peter

[toryglen-boy]

Who is aligned with magnetic South?

:shrug:

[dugnsuz]

Not me! True South's the way!!
This basic guide explains it (unfortunately no value for Canberra is given!!!)

http://www.myastroshop.com.au/guides/polar-align-basic.pdf

Doug:thumbsup:

[toryglen-boy]

Thanks for that fella, maybe he means someone else? i am aligned with true south.

:P

[tempestwizz]

Just bear in mind that even if you are perfectly polar aligned. and if the starting point of your alignment is perfectly at the 'home' position of 0.00 Hrs, 90 degrees, should your time setting not also be perfect for your location (E-W), there will be an initial pointing error of 15 arc minutes per minute of entered time inaccuracy.
Also consider that the 'time' you enter is for a time zone, ie same for Sydney or Broken Hill, and a given star will have a different relative RA angle in Sydney as distinct from Broken Hill.
Hence it is quite acceptable that the initial RA pointing angle is out. However, for a given location and accurate input data, that RA pointing error should start out reasonably consistent.
The DEC value should be close regardless of system timing inaccuracies.

HTH,

BC

[dugnsuz]

Try this too Duncan...
http://www.iceinspace.com.au/63-499-0-0-1-0.html
...I use similar to set up each time, works well!
Doug

[toryglen-boy]

LOL

Hey there B, i was wonderin when you wuold show up in this !!

TBH, after using it for a few night, the polar alignment is pretty much spot on, i seen a minimal amount of drift after 10 mins, and it looked pretty good. i do take on board what your saying though, the time entered is from my phone (Tempestwizz very kindly came round to mine last week, and showed me his excellent method of alignment) and is set to be almost exact to the second, from my location

My illuminated reticle and T-ring have just arrived, so i will practice my drift aligment during the course of the full moon, so i can see what i am doing. i guess after realigning again and again, the mount will 'learn' my locale.

after goingt hrough it, i know its user error, and not anything else !!

:lol:

[pmrid]

In answer to the question "Who is aligned to Magnetic South" see the posting reading:

Originally Posted by gmbfilter http://www.iceinspace.com.au/vbiis/images/buttons/viewpost.gif (http://www.iceinspace.com.au/forum/showthread.php?p=440954#post440954)
I have a HEQ5Pro
I set it to magnetic South with a compass
Level by eye, almost always do only 2 star align.Then it's "up up and away"
Its distance to initial alignment stars seems random and I don't worry anymore.
I would waste heaps of time fussing about with my initial polar alignment.
Drift alignment is a different issue.
Most errors are me aligning on wrong star.

'Nuff said?
Peter
I take the first 2 stars that come up in menu (unless they are behind my Hill)

[toryglen-boy]

so i see....

;)

[gmbfilter]

:eyepop:Oops I mean true south
Sorry about that!

The go accuracy is fine for me. I have a WO FLT110
everything I look for is neat center of eyepiece

I also use Starry Night Pro 6 to drive the mount, lots
more to see and find.

If accuracy decreases after a couple of hours I just realign

[TJD]

my nexstar 6 se is dead center even at 735x its just you got to set it perfectly:mad2:witch is anoying when the power goes out and it resets:mad2:


but goto scopes are more acurate than the person using them its almost allways user errer :thumbsup:

[CoolhandJo]

When I got my wedge for my LX200 I had all sorts of goto issues. I finally figured it out:

1. You really need to ensure you get true north (helps keep drift align quicker)
2. I use WCS program to do drift align first
3. Then I do a 2 star align BUT I release the DEC clutch to centre the first star! Then use the controls to centre the star in RA.
4. The second star is then align using the handbox only
5. This gave me near perfect goto!

Hope this helps a little bit

[Inmykombi]

My LX200GPS can find " fixed " deep sky objects with high accuracy.

However, when it comes to planets....sheeeeeeesh.....I dunno what its thinkin.
The planets are always off to the side of the eyepiece. Even with a wider field one. Nebulas and globs etc are alway spot on....

I have tried time adjustments/ tweaks, re-alligning and re-alligning again.
Nothing works.

I just put up with it, and centre the planets I can see in the finder. This doesnt help me with the ones I can see easily though. ????


Oh well. I still love my LX :P

Geoffro.

[marki]

I have never had any dramas with the accuracy of my HEQ5 goto. As long as you polar align it properly it will hit targets all night. If I am slack then the goto gets progressively worse over time but I cheat and resynch every now and again :P. My LX200 is always spot on whether it be planets or other objects in the sky. I do recalibrate the motors and sensors every 2 - 3 months and have carfuly set backlash etc. My biggest gains were made when I put a peterson tuning kit through it.

Mark

[leon]

With my G11 and Gemini GO-To it is recommended that one builds up a pointing model, this is OK if one dose not wish to ever undo the clutches and move the mount manually.

Although I do have a permanent set up on a pier, in my Observatory, I don't bother with this.

I know it is nearly spot on in South alignment so I just find a star at the beginning of the evening, center it, and sync it, and the rest is history, it will find any object for that evening.

I do this most nights, unless i need to image the same object the following evening, and then I do a warm restart and it hits it, right on target.

Leon :thumbsup:

[Merlin66]

Just a note/ comment Re LX200 fork mounts.
I've just replaced the dec bearing with needle bearings on my 10" and 12" LX200 Classics.
The GOTO before this "improvement" was OK and I could always find the object in the FOV.
When I removed the arms I marked their position ( so I could put them back correctly!!)
After reassembly I used the method recommended by Alan Sickland on the LX200 user group to ensure the dec axis was EXACTLY at 90 degrees to the RA..... guess what.... I found the original settings were almost 1.5mm out of true!! The OTA had been "adjusted" to attempt to compensate.
Now that they have been re-aligned ( within a couple of thou) the feel of the bearings is great and the GOTO ( I now use Alt-Az, instead of the wedge I still have, for spectro work) is 200% better.
What I'm trying to say is that the LX200 is a very capable machine, but the DEC/RA alignment needs to be checked sometime to ensure ongoing success.

[CoolhandJo]

I agree completely. I forgot to mention that I took my scope to forum member Barry who adjusted my forks to ensure they were orthogonal. This helped I am sure.

[g__day]

My pointing is okay so long as I check the time on my hand controller every month or so. I do about 3-4 realignments a year, and check my MaxPoint star model once or twice a year.

Pointing is accurate to 3 arc moinutes raw or 90 arc seconds with MaxPoint according to its sky model. So I generally just turn on the mount bypass the alignment (so it goes straight to the last alignment settings) and my gotos all tend to be centre of the CCD. Its good enough so I can remote image most nights (where its warm) - simply turn on everything and a few minutes later I'm kick off an imaging run then go play with the family. I break to check how things are going (remotely) every hour or so. I'm very pleased with the Atlux / SkySensor2000-PC combination at the moment.

[TJD]

my dob has got its even voice activated somebody says point to saturn and the goto(me) points it to saturn:D:Pand its so spot on no computer can match it:P

[CoolhandJo]

UPDATE of my LX200 gps from my last post. I couldnt believe that last night my GOTO's were off again! I mean, I did exactly the same thing as last time but this time there was less accuracy!

I normally just do a drift align (I know its accurate as I use WCS program and all is well). Then I power off and back on - Do a easy polar align. Centre on Sigma without viewing it (as my wedge is already drift aligned). Then when the scope slews to the alignment star I release the Dec clutch and manually slew to the star. Then I use the HBX to slew in RA (as I statred polar with RA at 0.0 and used a level to check already).

This worked PERFECTLY the night before - but last night didn't seem to work!

This has become a mystery to me now! How it could be so accurate one night and then not the other!

Anyone elese experience this intermittent issue?

[TJD]

that happened to me but the ather way around its usal that the tri pod isnt level

[Peter Ward]

Some truth there :)

As for my mount....My current T-point model (24 points) delivers all sky pointing of about 15 arc sec....but an accurate time base is essential. I find this helps

http://www.visualgps.net/NMEATime/

[CoolhandJo]

Peter,

One can only hope that the quote you have quoted stands true! It would be good if the user was the problem - people can skill up - but alas I fear that there may be mechanical and software issues at play with the LX200 gps series of scopes judging by the plethora of posts one can find on the net about goto issues with LX200's.

On the bright side there always seems to be a fix - and my summation is on the whole these scopes present good value for money.
If anything they force the user to learn a whole lot about the theory and practice of refining techniques.

[jjjnettie]

If I have any problems with accuracy, the first thing I do is check to see if the mount is still level.
I always recheck after changing scopes and cameras.
It's because I usually set up on the lawn, adding weight to the mount causes it to sink into the ground a little.
Don't trust built in bubbles, I use 2 small flat bubble levels or my digital one.

[pjphilli]

Hi - A lot of interesting replies! Just to add my three cents worth - after careful checking of level, polar alignment, times, location etc my HEQ5 is usually a fair way off on the first alignment star but having reset on this the second alignment star is very close to spot on. I then hand over control to my star chart program and star hop to my desired object, resyncing on the way if necessary. This usually puts even dim and small objects within my small DSI2 CCD chip boundaries. Cheers Peter

[CoolhandJo]

A strange thing happended last night! I did drift alignment, then did a 1 star alignment for my LX200GPS. I decided not to manually release the DEC clutch this time but "trust" that my mount was polar aligned and didn't bother looking for the first "Sigma" star (as it is supposed to be spot on anyway). As usual after centering the second alignment star my gotos were out a little bit. But I decided to use my Star Map softwarre program and slewed to Sombreo Galaxy. It was exactly dead centre on the DSI ccd chip!
I beginning to think my Long/Lat and time need to be checked on my HBX controller after everty GPS run!

[Barrykgerdes]

The alignment procedure for a polar mounted LX200 calls for a number of preliminaries. The most important is to find the true 90 degree point for the OTA before starting.

It then asks to adjust Sigma Octans using the wedge controls. This is what gives the most problems although it will be the best starting point. If your orthogonality is even just a little out you will have trouble in this area. It is far better to do a drift alignment and then (or) try to match the pattern of stars at the south pole to confirm the telescope axis and ignore the position of Sigma Octans and make sure that the next alignment star is good. The closer it is to Dec 0 the better.

In the Goto telescopes, particularly the fork mounts that have an orthogonality error, when doing a goto to stars towards the pole the closer you get to the pole the bigger the Goto error appears. This can be shown mathmatically also. No attempt to rectify the wedge should be made to correct any errors as the best alignment will be had from the drift procedure.

When I had my permanently mounted LX200 classic accurately polar aligned the startup procedure was to just ignore any adjustments of the wedge and Sigma Octans then line up on the second star. This gave Gotos within 3 arc minutes anywhere in the sky but Sigma octans was always out by at least the same amount. With my LX200GPS I never had to re-align it as it was always parked after use.

Barry

PS below is a picture of the south pole (30 arc minutes) area as it appears in a LX200 10" with a 26 mm Supper Plossl (32 arc minutes FOV) This is what I have always used for polar alignment. Adjusting wedge and Dec till revolving the telescope around the RA axis kept this view centred. A tedious process but in the end worth it.

[Bolts_Tweed]

Gday

I had a few problems with my HEQ5Pro similar to what everyone is describing. Prime focus photography objects were off by half a FOV somtimes after 3 star alignment (especially after a meridian flip). And this was when the mount was permanently mounted in an observatory and drifted in really well with a 2xbarlow & 5 mm eyepiece in a 960fl scope. I put it down to the way i have the scope & guide scope mounted.

I started using the PAE (Pointing Accuracy Enhancement) function of the Synscan system and all was fixed- amazing accuracy (tested at higher magnifications) - especially in the area that the PAE was performed in.

I am probably telling you something you know but a quick run down on the procedure for someone that doesnt :

1. Slew to a named star in the area you are concentrating on
2. Using the direction control buttons centre the object
3. Press & hold Esc - manual says for 2 secs but until hand control says recentre and the object name starts blinking
4. Make sure it is still centred and press enter

If I am imaging say in Sag. I will do this 2 or 3 times on named stars (doesnt have to be I think - you also use any objects that are stored in the handset) and the pointing is amazingly accurate then for the rest of the session in that general area.

Reading the manaual now it says the SynScan recalculates the model of the sky in the area you do the PAE in. This may be something like Sync'ing a Meade?

might be of help

MB

[toryglen-boy]

I ddint know that Mark, thanks. i am just grateful someone else posted in this thread who uses the same mount as me

:rofl:

[Bolts_Tweed]

NP Duncan

Just thinking about it - I have heard of epople having probs with PAE (I dont have any but just in case) so the other solution I used to use (thanks Rigs) was after 3 star alignment to perform a goto to a bright star so the supposedly intelligent electronics are sure they are pointing at it. ( 9 times out of 10 they werent). Then release both clutches and manually reposition the scope so it is pointing at the star then retighten the clutches. Do this 2 or 3 times in an area as well and goto is greatly improved. A bit primitive and brutish I know but I am basically a simple man looking for simple solutions.:)

MB

[Hagar]

Probably the most useful bit of kit you can use with any goto mount is an illuminated reticle eye piece. Use it for drift alignment and also for star alignment centering. It will improve the accuracy of your HEQ5 immensely.

[toryglen-boy]

i have an illuminated reticle, but never thought of doing this ...

thanks for the tip

:thumbsup: