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Mrjo90

Synscan GoTO accuracy

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I've got a Synscan AZ goto.  

i go through the set up, I.e  level mount, settings on Synscan, 2 star alignment and the slight manual adjustment you would expect to do whilst doing that.   Then when I use it, some objects are off centre.   Am I expecting too much, or can I make the mount more accurate ?  

 

Thanks

jim

 

 

 

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Hi Jim,
Are you finding the mount puts objects within your eyepieces field of view but not dead on centre? From your signature your gear (f/11-12 and eyepieces) will give you quite a small FOV in which to centre from the Go-To slew point which might be the 'issue'.  For comparison I use a 32mm eyepiece in my f/5 500mm Startravel 102mm refractor that yields a wide FOV to centre objects within and have never found the mount puts the desired object outside what can be seen in the eyepiece. There's a number of other potential contributing causes including in no particular order inputting the right co-ordinates in the correct order; accurate time and especially date (the American way); whether daylight saving time is current; mount being level (use a spirit level); judging when an object is 'dead centre' during the steps of the alignment routine; inaccuracies in the gearing of the lightweight mount; what alignment stars you use, balance of your telescope etc. on the mount; use of batteries or mains power and the inability of the mount to track accurately over long periods. All these little errors can add up.

Hope this helps.

Cheers,
Steve

 

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I always point the scope north then you manually align to the first star when you follow the 2 star alignment.

I am using a 20mm eyepiece to set up, the object falls into the FoV, however not centered.  I just wondered if there was a way to increase the accuracy, especially when looking for deeper sky objects that are harder to see.

 

 

 

 

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Hi i set up using an 18mm then when i have my target in sight i switch to a 10mm lens, centre object then press enter, then do the same for the second star. also if i 2 star align i will pick a star in the East, then my second star would be in the west.that seems to work for me. all the best. Scott

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46 minutes ago, Mrjo90 said:

 I just wondered if there was a way to increase the accuracy, especially when looking for deeper sky objects that are harder to see.

That could work in your favour as faint objects are easier to see with adverted vision, so it not being dead center could help.

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2 hours ago, Daniel-K said:

hi jim. are you polar aligning before set up?

The AZ-GOTO doesn't require polar aligning

1 hour ago, Mrjo90 said:

I always point the scope north then you manually align to the first star when you follow the 2 star alignment.

I am using a 20mm eyepiece to set up, the object falls into the FoV, however not centered.  I just wondered if there was a way to increase the accuracy, especially when looking for deeper sky objects that are harder to see.

 

 

 

 

The mount doesn't need to be pointing north before the star alignment so this will not affect goto accuracy. You might be able to improve the goto accuracy by adjusting the backlash compensation. The gear mechanisms will have a slight amount of movement in them and this can be compensated for in the handset. p12 of the manual http://www.opticalvision.co.uk/documents/127.pdf

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My GoTo Dob (really level slab to sit on)  works very well after a 2 star align, i use a 30mm EP to start with then increase the power   (smaller mm number) to get the star centered, then repeat on the 2nd star, the GoTo slewing after this is really good with DSO close to the center of a 17mm EP

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Same as Tinker above for me. I do have to level the tube well and then align with North though to get accuracy. I'm on v3.18 Synscan AZ.

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9 minutes ago, Owmuchonomy said:

Same as Tinker above for me. I do have to level the tube well and then align with North though to get accuracy. I'm on v3.18 Synscan AZ.

You need to update the firmware to v3.37
 

ps The last az only firmware was 3.08

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I don't know all much about the synscan software.  So I can only talk about my Meade Autostar.  However, I think it's worth my chiming in as there may be equivalent processes that you can do to improve the pointing accuracy.

 

1. Take you time when setting to the home position.   Level the tripod with a spirit level, doing it by eye isn't good enough.

2. Check your scope is pointing north, but don't put the compass next to the scope.  The metal in the scope will distort the compass reading, get the compass a few feet away, basically until moving it further from the scope stops altering the direction.

3. Update to the latest firmware if you haven't already.  There could be bug fixes.

4. Enter your current location into the software as accurately as you can.  OK, a few miles out shouldn't be an issue, but it's worth getting the GPS coordinates - most smart phones can do this accurately enough.

5. Calibrate the motors.  On my autostar there is a calibration routine that I can run through to training the motor drives.  You should only need to do it once, and be pedantic about getting it right.  This will have a huge effect on the pointing accuracy.

6. When doing the two star alignment process, try to use an eyepiece with a reticule. This will help you center the object properly and again will help with the pointing accuracy.

7. Don't use AA's.   Get a proper power pack.  I'd recommend a 17Ah battery or bigger.   These bigger batteries tend not to have huge voltage drops over the course of an observing session.  Especially if you insulate the battery.   When the voltage drops, it can mess up the pointing accuracy as well.

8. Don't move the scope manually, always use the handbox.  Loosening any clutch plates and rotation the scope in either Alt or Az will completely mess up everything.  Same is true if you move the tripod.

 

I'm sure there are some bits that you'll find useful.

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I found the motor calibration step is best done on Terestrial targets during the daytime.  So check to see if you can get that job done and dusted before wasted precious good weather :)

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Hi. 

I have the star discovery synscan too. If you download the pdf for it from skywatcher Web site, that will give you tips on how to get it spot on.

Tips like ending star alignment with either an up or right comand,   

Getting perfect alignment by de focusing eyepiece .

Power supply can be a big problem too, I used a 240 - 12  power supply from a security camera,  same polarity and correct output,  the scope would miss the target by a mile.

Took me a while to work that out. Thought I had a dodgy mount.

Nige. 

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On 28/01/2016 at 17:04, Nigel G said:

Hi. 

I have the star discovery synscan too. If you download the pdf for it from skywatcher Web site, that will give you tips on how to get it spot on.

Tips like ending star alignment with either an up or right comand,   

Getting perfect alignment by de focusing eyepiece .

Power supply can be a big problem too, I used a 240 - 12  power supply from a security camera,  same polarity and correct output,  the scope would miss the target by a mile.

Took me a while to work that out. Thought I had a dodgy mount.

Nige. 

Hi,

I'm having trouble aligning the mount (only had one chance due to cloudy skies)I've looked on the website for the pdf but can't find one with tips on alignment. Could you put the link on here please.

Edited by Wonkyhifi
Grammar

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