Tracking with no goto

[Ryan101]

Hi,
I'm a visual observer and just wondering if there is an option to upgrade my 12" dob to have tracking but not Goto.
The skywatcher Goto upgrade kit is $2000 and I was hoping for a cheaper option for tracking only.
I rather enjoy star hoping and would have no use for Goto.
Maybe it's just wishful thinking

[mura_gadi]

If your handy with a bit of wood and can get the mirror specs, I'd suggest copying the Celestron Starsense design.

or

If you fix your phone next to your finder and align against Jupiter you could use any of the sky software that gives your push/move to directions. That should work well with a wide view EP for locating objects.

or

Or Setting circles and star maps...

[astro744]

An equatorial platform also known as a Poncet platform will do what you want. These were popular many years ago before GOTO was common. I’m old school too and would rather use a map and memory in the car than a GPS and same for the sky.

Just search “equatorial platforms for telescopes”

There are expensive options with dual axis motors suitable for photography as well as DIY kits.

An EQ platform needs to be made for your latitude and be sturdy enough to take the weight of the telescope. You can simply position the entire Dob ground board on the platform or remove the ground board altogether and the platform itself becomes the ground board.

There was also a product by JMI telescopes (Jimsmobile) called Track’N’Train and was available for Meade Lightbridge Dobs. I have this on my 16” f4.5 but tend not to bother with it. Depending on the position of the target T’N’T either works well or not so well. I also have an EQ platform for my smaller Dobs which I only use for planetary observing when wanting the target to stay fixed for longer periods. An EQ platform will get you about 45min of tracking before needing to be reset, (takes seconds to reset).

There is also ServoCAT which will give you GOTO but you can simply track Alt-Az if you want. You’ll get field rotation over time but for visual it doesn’t matter and the rotation is slow. I’ve never used ServoCAT and am unsure if you can simply push to a new location manually and it picks up from its new position. I would not like it if I had to use the motors to drive it everywhere.

[Ryan101]

Thanks for the info guys.
As a guitar maker I'd say I'm fairly handy with timber so I'll definitely take a look at the starsense option. I'd much rather make things myself if I can.
Just to clarify, would the Poncet platform turn my dobs az capabilities into an eq mount?

The first thing I learnt about mounts is that I'm not an eq fan what so ever.

[astro744]

Your Dob will still have the same Alt-Az movement but the whole thing will ride on a platform that is tilted and has a large sector underneath and a pivot point. The arc length of the sector determines maximum duration before having to be reset. Usually 45 min or so. The angle of the sector is custom made for your latitude (with a bit of leeway). Stepper motors drive the sector.

You still have typical Dob movement but it all rides on a platform that tracks the sky for approx 45min. The platform itself needs to point north-south and be level with the sector on the side of the celestial pole that is above the horizon, I.e. south for Southern Hemisphere. It adds about 15cm to the height of the Dob.

If you’re handy with wood you can build a platform but also need a little bit of electronics to drive the stepper motors.

Here are two links at both ends of the price spectrum:

https://www.oreilly.com/library/view/astronomy-hacks/0596100604/ch04s21.html

http://www.equatorialplatforms.com/

There are many others. Also search for plans and kits.

[Greggles]

Hi Ryan,

Some great info here from astro.

As mentioned a diy eq platform might be a good option for you. I have a 10" dob and have built acouple of eq platforms of different designs. All worked fine but I slowly slowly perfected the design so I could do some basic photography as well as my usual visual observing.

My final design uses the Ed Jones design and I couldn't be happier. If you have any questions please feel free to ask as I'm happy to share everything I've learnt over my builds.

Greggles

[Ryan101]

It seems good eq platform blueprints are hard to come by.

[astro744]

I didn’t build anything and bought mine complete from a Bintel many years ago but it is no longer in production. See previous thread on similar topic.

https://www.iceinspace.com.au/forum/showthread.php?t=189308

[iborg]

Hi Ryan

I know that ASV were working on something like this. I have seen one working, might have a prototype mind you.
Try contacting them.


Philip

[Greggles]

Lots of general designs but blue prints are hard as a platform needs to be made for your specific latitude and your scopes centre of gravity.