[FOR SALE] Skywatcher Synscan GoTo flextube 300p Dobsonian

[ahmed_haider (Ahmed)]

Hi all,
With much regret am selling my Skywaycher 300p goto dob.
Comes with: 9x50 finder scope, Skywatcher shroud, single speed focuser.
Also includes a Sky-watcher synscan wifi adaptor.
Note: this version does NOT have the Wifi adaptor built-in i'm offering it as an add-on. It will replace the hand controller and connect to your mobile phone synscan app.

Reason for selling: I'm buying a 5 inch triplet APO and need funds.

This is an excellent visual tool, although I used it for a bit of astrophotography as well (pics attached). Collimation is a breeze and it keeps collimation really well for the secondary mirror. For the primary you need to collimate almost every time if you move it.
I've always kept it indoors when not in use, the tube has some scratches (came from sticky tape that was accidentally stuck on it) But no dents or damage.
Mirrors are clean and views are very sharp!
It tracks really well!

The velcro attached to bottom of tube is for balance when trying out astrophotography (not required for visual observation).
Note that eyepiece is NOT part of the sale.

Price: 1700 AUD negotiable within reason. Pickup plz Blacktown, NSW
This thing cannot be posted. I'm open to driving up to Newcastle, down to Wollongong or west to Blue mountains to deliver it......but you probably might want to come yourself and take a look.

[ahmed_haider (Ahmed)]

So just to be upfront the pictures I've taken with it were with a Mallincam reducer/corrector (also on sale on here)
And a 2 speed focuser installed. That focuser not for sale here I'm using it for my other imaging Newtonian.
The focuser attached to this scope is a single speed one which not that good. It's still perfectly fine for visual though.
But I'll reduce the price to 1900 AUD pickup plz.

[ahmed_haider (Ahmed)]

Being sarcastic here

But price lowered to 1800 AUD pickup from Western Sydney plz

[ahmed_haider (Ahmed)]

Finally some clear (ish) weather here so i'm doing a bump and price drop.

$1700 pickup from blacktown, western sydney

Cheers
Ahmed

[astronobob (Bob)]

Hi Ahmed,

Good bang for buck these scopes, and this one is growing on me, got rid of all my gear a few years ago, and thought if I ever go a scope again it would be a GoTo Dob, simply for the simplicity,

But before I cave in, can I ask some idea of the camera used, exposure and subframe amounts for those images, Not all three but capture method roughly, was it Lucky Imaging Technique or not ? like 1 sec and hundreds of them, or similar, maybe something else ?
They are not too shabby considering No Guiding I believe ?

Thnx for any feedback

[ahmed_haider (Ahmed)]

Hi Bob,

Yes the scope is awesome, I'm sad to let it go but I really need to reduce the size of my setup (hence going for the refractor)

Anyway to your questions. I use a ASI533MC camera with a mallincam reducer/coma corrector. It's a budget alternative to Starizona Nexus. Although there's still coma at the edges but it does reduce my 1500mm focal length to ~1150mm with F ratio down from 5 to 4.

I used this excellent presentation as a starting reference: https://www.youtube.com/live/ypheEr4...p2LUNHxQzYbxi1

Practically I found there 3 big issues, so here goes below, the issues and my (half-baked) solutions

1- Tracking issues:
This scope is not meant for astrohpotography so it doesn't track well enough for this purpose, although once aligned properly it keeps objects well centered generally. But I found I couldn't go above 3 seconds of subexposure otherwise I get elongated stars.
My solution was 3 seconds of sub-exposure time. I use sharpcap as acquisition software and set FWHM filters to filter out frames with tracking issues. Which aren't many when aligned properly.
Here the fast ratio and the big light collecting area give me a great advantage.
For proper alignment I need to repeat the 2 star alignment around 3 times over, get the scope on as stable a platform as possible. And re-do the alignment when slewing the scope over a large area of the sky.

2- Field rotation:
Thanks to the dobsonian style mount, but I found AstroPixelProcessor to be the best stacking software for this issue. Ofcourse I still need to do some aggressive cropping because the edges come out awful. Depends on how long the total exposure time is of course, for around 12-15 mins of total exposure the field rotation is not bad.

3- Balance issues and pointing to the zenith
Because the center of balance on altitude is fixed for this dobsonian mount I need to attach weights to the bottom part of the tube to balance with my heavy camera and reducer combo. So there's velcro pads glued to the bottom part of the tube I normally attach my mini-pc there and balance with it
But the dobsonian does NOT track well near the zenith no matter how well balanced it is. So I'm limited to object below 75 degrees altitude.

BTW if you're interested in astrophotography with this I will include the 2 speed focuser to it. It's much better than the single speed one currently attached. The mallincam reducer was on sale here but I didn't get any interest so I've withdrawn it, let me know if you're interested in it.

Cheers and clear skies!

Originally Posted by astronobob

Hi Ahmed,

Good bang for buck these scopes, and this one is growing on me, got rid of all my gear a few years ago, and thought if I ever go a scope again it would be a GoTo Dob, simply for the simplicity,

But before I cave in, can I ask some idea of the camera used, exposure and subframe amounts for those images, Not all three but capture method roughly, was it Lucky Imaging Technique or not ? like 1 sec and hundreds of them, or similar, maybe something else ?
They are not too shabby considering No Guiding I believe ?

Thnx for any feedback