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Alignment help! Dobsonian 12" synscan goto tracker


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Hello all :)

I am having problems with the alignment of my telescope mentioned above. Does anyone know of a  super detailed and bulletproof guide somewhere? A guide that doesn't jump over any steps, no matter how insignificant and self explanatory they may seem.

I have tried youtubing and reading the guide that came with the telescope, over and over again. But I simply cant get it right.  Since I am a beginner at this, unfortunately I cant come closer to what I am doing wrong - its all up in the air :) 

Thanks in advance for any help!

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No experience of the dob versions, I guess polar alignment isn't needed on these?

I'd recommend the phone app SynScanInit 2 tho as that will give you the exact details you need to enter into the handset so it has the correct Lat/Long and time format which often trips us up until you get used to what and how to enter it.

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My mini synscan dob base needs to start with the N on the base unit facing north and the base as level as you can.

The tube set at altitude 0 with the open end facing north and the tube is horizontal

Connect handset

Turn on mount

Press the right hand button to accept the sun warning then following Dave's syscaninit post check the app and make sure the handset matches each configuration step as you cycle through the handset steps, the step moves forward as you confirm the previous step using an upper right button, the lowest buttons change for example yes to no in the daylight saving question. 

When initial setup complete I say yes to alignment

I use two star alignment

Then choose the region of the sky where you can see a star and on the handset using the bottom left right keys (not direction keys) choose the sky section. If you use the wrong buttons you won't see the star offered change so try another of the bottom buttons..

Now scroll through the stars listed until you find the one you want, select it

Select ok to view it then use the buttons to centre it on the lowest powered eyepiece, confirm, then check the handset to either fine tune alignment further or select the second star by scrolling through the list offered and choose the one you want. Select your chosen star and repeat fine tuning as the handset prompts.

I can't always see the stars from my location so I just accept where the mount slews to with no fine tuning.

I didn't learn how to use the synscan handset until I downloaded the skywatcher synscan manual which helped.

Hope that helps.

 

 

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Welcome too and I hope you have success soon, you can practice inside just make sure the telescope has enough room all round to slew all directions without touching anything.

Hopefully there aren't too many mistakes above as I typed it from memory.

Edited by happy-kat
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  • 3 months later...

Thanks for the replies. I have tried what you have all suggested. I am getting closest to alignment with the synscan app. I level the telescope and point it north. But when the telescope  moves to align now, it is blocked from moving where it wants from the back support on the mount. The motor just keeps trying to align, but it cant move. I have tried selecting different stars, a lot of different stars, even polaris which is extremely visible and should be easy to move straight to. But the telescope chooses to move in such a way that it gets blocked every time. Any suggestions?

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6 hours ago, Thor123 said:

it is blocked from moving where it wants from the back support on the mount.

This may be a bit left-field, but is your base assembled back-to-front. My Skyliner 250PX does not have a back support, just 2 sides and a front.

1164133043_Dob(2)R.jpg.56ffd1ad337d836108b7a9b53e647d55.jpg

The optical tube can swing from just below horizontal (facing forwards) to vertical, (and slightly beyond, before the primary mirror end hits the inside of the front support). The photo shows an additional weight at the top of the rear of the tube, as I found the balance was a little front-heavy when I used my binoviewer.

Geoff

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Your base looks fine.

Initially, I had problems with alignment. Quite often, the suggested second star was behind a roof/tree/fence. I spent some time with the "Stellarium" program, on my PC, and produced a table of 14 of the brightest stars visible from my back garden, and for dusk, at the middle of each month of the year, selected a few, with compass direction and altitude. By aligning at dusk, the bright stars are easier to select - you do a manual slew to the first, and the mount does an automatic slew to the second, and it is usually visible in the finder.

1807229252_SynscanAlignmentStars-NorthSomerset.jpg.75289fc034b7e03127f87283a15d2327.jpg

By selecting 2 stars with about 90 degrees difference in azimuth, and 20+ degrees difference in altitude, the Synscan software gets the best input conditions to compensate for errors in leveling the base. At the moment (mid March-ish), I usually start with Sirius.

I have added a large bubble level to the base, and use a wedge under one of the feet to centralise the bubble. The handset gives altitude and azimuth for the first star, so I set that value on the altitude scale, and then slew in azimuth, standing behind the optical tube, until the tube is pointing towards the star. By aligning at dusk, I can complete alignment, and the mount will continue tracking whilst I go in for a warm drink, and wait for the sky to go properly dark. If I have done my alignment properly, the 2nd star will still be in the field-of-view of my 32mm Plossl eyepiece, when I come out again.

Geoff

Edited by Geoff Lister
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Welcome to the forum, Thor123! And congrats on your 12" choice. The best portable aperture IMO.

Selecting different stars wouldn't help. As hitting the wall means you are having some general system malfunction or misconfiguration.

Double check your location, time, and time zone set correctly. Use align with single brightest star method (don't use Polaris or any stars close to it). Do Factory reset from the menu and try again.

One wild idea is perhaps you are pointing only manually? Are you engaging the clutches? Try using the controller arrows exclusively for that. Confirm that both motors are working.

Also I recall the trick to get the controller out of wrong prior alignment:
First, point to a bright alignment star manually but don't engage clutches.
Now command to align to that star as usual, but hold the OTA by hands in the direction of the star while motors are slewing (clutches not engaged).
When it stops, engage clutches and use remote arrow keys to point to that star precisely.
The method may not work if DSC's are independent from motors. In that case motors should work indefinitely, or some error will be displayed.
(I assume you know bright stars visible in your sky enough for the task, as that's another reason the alignment may cause OTA hitting the wall on the second star).

Just on a side note, you don't need starry sky to try the above. Just use some digital planetarium app to approximately estimate which star would work at that time of the day (high enough above the horizon).

Edited by AlexK
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AlexK has some useful ideas.

I noticed that your second photo shows what looks like a clutch adjustment knob on the side of the altitude gearbox. My Skyliner does not have this, and mine (over 10 years old) has the handset cradle mounted across where that knob would be. My Skyliner mount has dual encoders for each axis (1 for the motor and the second for the axis shaft) but uses friction, adjusted by setting 2, big, Nyloc nuts, to move the mount. The nut setting is a compromise between ease of manual pointing and reliable motor drive, and is not easy to adjust during a session. I found that I had to tighten the altitude nut to get reliable operation with a heavy eyepiece/binoviewer/DSLR, and added the rear weight to help the balance.

The Skywatcher mounts, also including my Skymax 127 and Virtuoso 90, are essentially "Dumb" when used with the Synscan handset, and the encoders are just clockwise/anticlockwise pulse counters. At power-up, the GoTo software's axis angle registers are set to zero, which equates to OTA horizontal and pointing to celestial North. If you had ended your last session with <Park> <HOME>, and not moved your mount since, then at the next power-up, the mechanical and electronic "model" will be aligned at zero.

The alignment process is most accurate if your azimuth axis is perpendicular to the Earth's surface, i.e. the base/mount is level. It is much easier to get the base level to under 1 degree, than it is getting the OTA pointing, with a similar accuracy, towards celestial North. With my mount, when I set up on my patio, I move the bottom part of the base round until the bubble level has its bubble pointing away from one of the feet, and then slide a wedge under that foot until the bubble is central - job done. If you choose your first alignment star close to the horizon, the azimuth alignment will be accurate as soon as you centralise the star, and any small leveling (altitude) error in that direction will be measured. If you choose a second star at 90 degrees in azimuth from the first, the mount will also measure the leveling error at a 90 degree compass direction; so as the mount rotates, the software will add, or subtract, a proportion of these two errors, to give a more accurate GoTo (and also tracking once the target is acquired).

Geoff

Edited by Geoff Lister
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I would not worry about the leveling perfection on a modern GoTo mount. Simply following the 2 stars alignment as suggested by the handheld would take care of ~5 degrees of error in there. It's still good to have to make the life of the wooden GoTo fork motors easier (thus more accurate on a long range slew, but not because of the closer refined model conformance, just due to mechanical deficiencies of such a wooden mount construction). If in doubt, at any moment you can do the single star alignment in the vicinity of your target (called PAE, i.i.r.c.) and have much more pointing/tracking accuracy gain than any leveling effort could ever provide on these mounts trying to crossbreed the Dobson stool with the GoTo fork (quite an ill idea in my opinion, but seems to be OK for visual tracking if you're OK sacrificing the weight).

If still no go (to) :), I would suggest you to photograph the piece of the instruction you are trying to follow, and we (or I'm) could try to "decipher" it for you into more detailed step by step with needed "sanity" checks along the way.

Edited by AlexK
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  • 2 months later...
On 08/03/2021 at 03:02, Thor123 said:

Nice, I will try this ASAP!

Hello people.

I have exactly the same problem with the same dobson.

The synscan is v3.

Could you fix it?

Greetings

Edited by pablocarlac
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  • 6 months later...

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