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over and under v side by side

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#1 telecasterguru

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Posted 18 May 2009 - 05:46 AM

I was after some advice on the pros and cons of mounting scopes over and under or side by side on my EQ6.
I have two refractors an 80 and a 127 and also a 200mm reflector.
Thanks
Frank

#2 David Pavlich

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Posted 18 May 2009 - 07:26 AM

The big bugaboo is achieving good balance with a side by side setup. I found it so aggravating that I went back to a piggyback arrangement. The negative about piggyback is that you raise the center of gravity which in turn, requires you to use more counterweight. I think the best multiple SBS is a triple with the heaviest scope in the center and carefully placing to two outboard scopes to equalize the loading on the Dec axis.

If the two scopes are of similar weight and length, it's not as bad, but if you have two very different scopes, it becomes an exercise in frustration.

David

#3 donsinger1

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Posted 18 May 2009 - 11:20 PM

Have done both...I think I like SBS because it seems to lower the center of gravity somewhat, but you can offset that by using more counterweight on a piggyback setup.

I think I like SBS because I can use more scope combinations than piggyback.

My current setup include an AT90EDT on one side (about 14 lbs with everything) and a WO66 used as a guidescope...weighs about 7 lbs with gude cam and x/y positioner. But, I have no problems balancing in my CGEM...you just need to make sure you are balancing in three dimensions.

Don

#4 telecasterguru

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Posted 19 May 2009 - 03:00 AM

Thanks for the advice. I think balance is going to be the biggest issue with side by side.
Extra weights required as a result of a higher centre of gravity is the issue for piggy back.
I currently piggy back so I should give side by side a go and see how it works.

#5 rdegoutier

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Posted 19 May 2009 - 10:24 AM

My current setup include an AT90EDT on one side (about 14 lbs with everything) and a WO66 used as a guidescope...
Don


Can you please post a picture of your setup? I use piggyback, but would prefer SBS and need some ideas on how to do this effectively. My main scope is a Sky-Watcher MAK-Newt 190.

Thanks
Robin

#6 LLEEGE

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Posted 19 May 2009 - 12:01 PM

I'm with Dave. I tried both and prefer O/U. But, I was using a big SCT next to a 5" refractor. I would imagine two similar size/weight scopes would benefit from S/S.

#7 AlexN

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Posted 20 May 2009 - 05:32 AM

I'll put a vote in for both sbs and under over...

My side by side setup was fantastic with my 4" APO and 3" guide scope, and with my 8" newtonian + 6" achro.... but with my C11 + ZS66 or the C11 + ST80, the under over setup was far easier to balance... My mate happily uses a VC200L and a 3" refractor guide scope side by side,

If your scopes are of relatively similar weight, side by side can be fantastic, however if you use two very different telescopes then under and over is usually much less of a frustration...

#8 JAT Observatory

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Posted 20 May 2009 - 08:36 PM

I have both a SbS and O/U. The LX200R has a SV110ED mounted on top of a DM12 rail.

Between the SV110 rings is a custom drilled ADM SbS plate that has a dovetail adapter which allows it to be mounted to the DM12 rail on top of the LX200R.

On one side of the ADM SbS is a WO-66 with a Mallincam. The other side has a GStar-EX (with a 2.6mm lens) and a SV-F50 finder.

#9 JerryWise

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Posted 21 May 2009 - 08:09 AM

I do both too. I have a FS-78 mounted on top of a TOA-150. Beside that on a Robin Casady SBS plate is a C-11. Wedged down between the TOA and C-11 is a little FS-60c. This about covers the focal lengths needed for some light DSLR Astrophotography.

Might be just me but if the over and under can be mounted on top of sturdy rings holding the main scope I'm more comfortable. When mounting directly to plates and adapters screwed to the SCT tubes there is more potential for flexing. The more innovative you get the more you develop extra skills. I'm now pretty good at drilling precise holes and using a die and tap set. You can do wonders when you put your screw holes where you need them.

#10 JAT Observatory

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Posted 21 May 2009 - 01:06 PM

I agree on the less flex if SbS is mounted on top, but in my case I am limited to the 24" opening of my domes slit.

Mounting them lower reduces the size of the total optical circle the dome software uses to correctly position the slit. Thus I have a better shot of not having the slit's edges block any part of my optical path.

#11 Mark Jenkins

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Posted 22 May 2009 - 01:14 AM

I am about to try SBS. I have a TEC 200MC and an Astro-Physics 130mm GT.

I just ordered a Casady Tandem 16.

The TEC weighs something like 26 lbs. while the AP weighs in at only 15 lbs.

Thinking I may have to add some weight to the 130 side of the arrangement.

#12 groz

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Posted 22 May 2009 - 05:24 PM

The TEC weighs something like 26 lbs. while the AP weighs in at only 15 lbs.

Thinking I may have to add some weight to the 130 side of the arrangement.


Why not just move the sbs adapter one way or the other till the full setup balances ? That's what we do, and we have no problem reaching proper balance. Using dual saddle adapters from kens rings (vixen style), the bar slips into the saddle on the mount. Each scope goes into one of the saddles on the bar. I can move the bar side to side, then move scopes forward and aft in the respective saddles, till everything balances out just fine.

The setups here are _not_ balanced, I just quickly tossed it all together one day in the living room to take the picture, but, it shows how ours all go together. The twinned 80's atop the heq5 are way off to one side (because of where it's sitting in the living room), but you can see, just moving the bar to the left will balance it all out. The SCT+Mak combination is off centered enough so that it is very close to balance.

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#13 Doug76

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Posted 22 May 2009 - 09:27 PM

Well, I like an over and under, but your asking about scope mounting. Side by side in that case.

#14 Mark Jenkins

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Posted 23 May 2009 - 12:16 AM

The Casady Tandem slides side to side in a saddle on the mount. I forgot about that!

I should not have any problem balancing the Mak and the 130 GT.

#15 Rudy Nix

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Posted 23 May 2009 - 04:28 PM

I use both methods for mounting my scopes, but prefer the SBS. I am forced to use the over/under method when I use my Meade 10" SCT and guide scope combination because the Vixen style saddles and dovetails introduce too much flex with the weight of the SCT. I will be switching them over to the Losmandy style saddles and dovetails and will probably use the SBS exclusively.

#16 telecasterguru

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Posted 25 May 2009 - 12:10 AM

Thanks for all the advice everyone.






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