Side by Side or Stacked Mounting

[Raydar]

Hi,

Interested to know what people think of a side by side mounting configuration as opposed to a stacked configuration. I've bought a new mount, astro-physics 1600GTO and it can slew and point a 100kilo setup (not including counterweights). I'll be placing my C14 and Solarmax 90 onto this mount.

Even though these two scopes don't come anywhere near the limit of the mount I'm thinking by keeping the weight of the scope closers to the mount's centre of gravity with a side by side setup that this could be better for pointing and guiding accuracy.

Any feedback regarding pro's and cons greatly appreciated.

Regards

Ray

[pdalek]

With a side by side configuration, each time a change is made to the attached gear, the dec axis must be rebalanced in two directions
- fore and aft, just as for a single scope
- sideways, either by sliding the double mount or by altering the weight on the other side.

[PRejto]

Another consideration might be whether you want to, or need to, point both scopes at the same object of interest. Doing so might be easier to accomplish with a side x side + something like the Optec Libra. The Libra will allow you to accurately point the smaller scope. You might be able to do this piggyback but there might be mounting difficulties.

Peter

[Raydar]

Thanks Pat, thanks Peter.

I'm thinking that having piggyback arrangements cause the centre of gravity to move out further from the mount, and that would cause wind, vibrations and other inertia to be more accentuated in the scope than if the counterweights and telescopes were closer to the mount. I'm thinking the closer the weight to the mount the better. However as you have mentioned there would be increased balancing issues and also the possibility of the scopes hitting the mount as opposed to them being stacked.

Hmm, decisions, decisions.

Ray

[jenchris]

I think the only thing that should be side by side is a Shotgun
I think under over is a far better solution and only one gets wet when it rains

[h0ughy]

best of both worlds,side by side and under and over

http://www.iceinspace.com.au/forum/showpost.php?p=670607&postcount=253


http://www.iceinspace.com.au/forum/showpost.php?p=939073&postcount=297


http://www.iceinspace.com.au/forum/showpost.php?p=1038206&postcount=322

[Raydar]

Thanks guys. Dave you ever have any issue with the SBS setup not pointing both scopes out of the sirius dome slit at the same time?

Ray

[h0ughy]

at some angles yes, with the large scope and the refractor, but with the refractor cluster i was able to image the sun in white light and Ha at the same time tracking for over 6 hours. the dome movement was checked every minute for movement

[pdalek]

About the meridian the side by side requires less dome aperture width than piggyback.

The SBS hardware is heavy, so for a heavy plus light scope combination, the PB configuration will give the lower total load, i.e. scope and counterweight, on the mount.
With two heavy scopes, the reduced distance from axis of the SBS will require a smaller counterweight and give a lower total load.
Total load and pier/tripod stiffness determine overall vibration.

If using a range of scope combinations the SBS is far more convenient.

Both SBS and PB require a little more work to zero out cone error.

The image shows what I use.

[Raydar]

Okay, interesting. Thanks again guys.

Dave (off topic) but what software do you use to keep your dome tracking the telescope over long exposures? Just curious to know what else is out there.

Cheers

Ray

[h0ughy]

ascom dome and gemini with the maxdome controller

[Nortilus]

I have gone SBS recently as it makes it easier to swap main mounts and leave my guide scope alone. Balancing everything doesn't take long if you know how.