Piggybacking

[dpastern (Dave Pastern)]

Hopefully someone can point me in the right direction. I have a SkyWatcher Equinox 100 OTA at the moment. I'm looking at (eventually, later on this year), getting a 2nd, smaller OTA for guiding. Never having seen this in real life, what do you need to connect the 2 OTAs to each other? I know that you need tube rings, but I'm trying to visualise how they connection each OTA etc. Do I need to drill holes into the current OTA to allow some ability to fit them etc?

I know this sounds like a silly question, but better to ask than not to.

Dave

[RB (Andrew)]

Dave, I use solid tube rings around my main OTA with a Losmandy bar on top which I can clamp another set of smaller solid rings on top to hold my Orion short tube 80 guide scope.
Don't bother with adjustable guide rings, get the solid ones instead to minimise flexure.
These rings just clamp around the OTAs and you tighten the knobs to hold them in place, no need to drill any holes in the OTAs.

I've also got another Losmandy bar on top of my short tube 80 so I can piggyback a camera as well if I want widefields.

I don't have any pics atm and I'll be logging off soon but I'll see if I can find some pics and info for you.

[Barrykgerdes]

Hi Dave

The biggest problem encountered in piggybacking a guide scope onto your imaging scope is flexing. Most piggybacking is done with an array of comercially available clamps and rings on a bar that is fitted to the supporting scope. This is probably the best that most people can get but if I was doing it I would custom make the mounting components to attach to the most rigid parts of both scopes and fasten them firmly over the longest possible baseline. Avoid attaching to the actual tube part of the scope.

The most important thing to have though is the best possible equatorial mount you can get and don't overload it. If the mount is not stable even the best scopes will give mediochre results. Wide angle photography is not so stringent but when you want arcsecond resolution absolute smoothness of tracking is imperative.

Barry

[AlexN]

Here is a shot of my piggy backed setup.. everything is solidly bolted down so there is little to no chance of flexture..

What I have is the dovetail bolted to the imaging scopes rings, Another dovetail bolted on top of the imagers rings. I have my guide scope bolted hard to that second dovetail by means of the guide scopes L mount... This setup is extremely rigid, and guiding out to 20 minutes has not been a problem..

I agree with Andrew.. Steer clear of adjustable guide scope rings. They are a constant disaster in my experience.. Mount everything as solidly as possible. This will ensure that at the end of your nights imaging, your hair is still on your head, rather than strewn across the ground..

[Ian Robinson]

Even better , don't use a guidescope , use a good quality off axis guider , it's a much cheaper and better arrangement all round.

[marki]

Originally Posted by Ian Robinson

Even better , don't use a guidescope , use a good quality off axis guider , it's a much cheaper and better arrangement all round.

Thats OK for native FL but how do you attach a reducer/flattener and keep the right lenghts? I have this problem right now and either have to use a guide scope or OAG depending on whether I use the reducer or not.

Mark