Dual mount or Piggyback?

[Woody]

Hello everyone

I currently have a little Skywatcher ST80 and I am soon going to buy a Skywatcher 80ED Apo. Will be using the Apo for imaging with a DSLR and the ST80 for guiding with a QHY5. My mount is a HEQ5.

I was looking at this for a dual mount bar

Accessories @ Modern Astronomy

for £99.

Or is the ST80 piggybacked on the 80ED a better option? I like the idea of the dual mount bar as it may be better balanced but I am unsure on all these matters.

Your ongoing advice is greatly appreciated.

Jeremy

[Woody]

Have been doing a little more research and may have answered my own question. Is there a risk of some flexing in the imaging OTA if it is piggybacked with a guidescope?

Thanks

[barkis]

I think the majority of imagers favour the side by side configuration.

using the dual mount bar. Flexure is less of a risk. The guidescope needs to be secured in a sturdy pair of guide rings, unless you are opting for the Alt Az. guide mount.

Ron.

[fatwoul]

I've tried both, and to be honest I've found benefits and drawbacks for each method.

Side-by-side does indeed seem more rigid, and puts the combined centre of mass of the scopes closer to the mount. This reduces the amount of counterweight needed, sometimes by a surprising amount.

However, I find my side-by-side configuration to be a nightmare to balance, because there are two axes of adjustment. The only way I've been satisfied with so far is to find the balance for each scope individually, with cameras etc attached as they would be in the final configuration, and then mounting them onto the dual bar. The balance between the two scopes then needs to be adjusted by sliding the dual bar itself back and forth, which means loosening it. This can be a little terrifying when you have a lot of very heavy tubes and cameras hanging off it.

In my final, permanent setup, I will use the dual bar. But until then, I find piggybacking to be a lot more simple.

[Woody]

Thank you both for the replies, looks like dual mount is the way to go.

Cheers

Jeremy

[Zakalwe]

I have mine mounted side-by-side, on a Gemini bar. I didn't find balancing to be too much of a chore*, but I am using two scopes roughly similar in weight. If you had a SCT and a wee refractor guidescope, then it might be a bit more difficult.

*Please note that I am an idiot when it comes to this stuff, so I might be doing it totally incorrectly. I am able to get 200 second exposures in this configuration though (unguided).