SCT 8" and SW ED80 best mounting?

[Nico13 (Ken)]

Hi all,
I have just picked up a SW ED80 off IceTrades and will be mounting it with my Meade 8" SCT and was wondering which is the most common / most preferred method of doing this.

I will be mounting them on my NEQ6 Pro mount and would like some opinions as the both scopes will be used for some visual as well as imaging and as they both will have their pluses and minuses also not knowing the best method it's ask the experts time to help sort out what I should do, namely side by side or piggy backed????

I will have to purchase some hardware for either method so before I spend some dollars all opinions would be welcomed.

Thanks

Ken.

[g__day (Matthew)]

Ken,

Flexure is you're number one enemy, so regardless of whether you mount side-by-side or piggybacked - or even build a craddle out of hardwood (and hey - that could actually work and be cheap). The single most critcal component in all your options is can you minimise differential flexure to an acceptable level for your goals. Some designs allow way too much movement of one of both of the tubes, and it only needs arc seconds of droop to spoil things. So all I can say is go robust. Losmandy gear is good, Robin Cassidy gear is better, ADM is fair to good.

My views having mounts 3 OTAs - two side by side and the third piggy backed - all with Losmandy gear

Matt

[multiweb (Marc)]

Was about to say that. ADM is very affordable. If you go side by side or other make sure everything is rock solid. ED80 is not a heavy scope and C8 relatively small so you should get away with flexure.

[Nico13 (Ken)]

Thanks guys,
The new EQ6 will accept both Losmandy and Vixen dovetails, both scopes have Vixen but I guess I could use a Losmandy saddle bar with the Vixen adaptors.

Got to go to Bintel in Melbourne at Saturday to pick up my mount after repairs so will have a good look at mounting options while there, expensive little buggers so I want to get it right.

Ken

[g__day (Matthew)]

Ken,

I put a Losmandy Tak head on a Vixen Atlux (they match perfectly) to hold a Losmandy side by side bar - absolutely no flex in this - rock solid. Next I got the Losmand D saddle adapter to fit a C9.25 to one of the side saddle bars - excellent rigidity.

What I did next was a total compromise:

1. I put a 127mm MAK in the second side saddle using a pair of the largest Losmandy O rings with 3 point bolted adapters

2. I put the C9.25's original wide Vixen dovetail on top of the scope and used this to connect a Williams Optics 80mm Megrez again using a pair of three point bolted adapters.

These bolted adapters where necessary to align the optical tarins of all three OTAs to the same target, however three slim 2-3 mm diameter bolts are simply not robust enough to hold my smaller two scopes without some differential flexure - probably quite a lot.

It's the aligning the OTA's light path that kills rigidity. The only system I have heard that really works - to align two OTAs correctly yet maintain strict rigidity on both is a Robin Cassidy Tandem Guidescope Aiming Device http://www.robincasady.com/Astro/TGAD.html

They are moderately heavy and cost around $500 landed - but it seems they alone perfectly do the job.

Interested in other folks views. If you want to rigidly mount and align two or more telescopes light paths what other device can you use?

If you had a large SCT and high end mount - you could build a rigid cradle to swaddle the entire OTA and let a second or third OTA be attached to the craddle and light paths perfectly aligned (which would really cost - like high end RCs tend to do).

[Merlin66 (Ken)]

IMHO I'd go for a side by side plate..
I mounted my 6" f3.8 and the ED80 on the HEQ5pro...
(I later changed over to Losmanday dovetails..)
A good rigid set-up no issues..

[Irish stargazer (John)]

I use the ADM mini dovetail on my C 11 to hold my Megrez 72 and it is rock solid.

[Nico13 (Ken)]

Originally Posted by g__day

Ken,

I put a Losmandy Tak head on a Vixen Atlux (they match perfectly) to hold a Losmandy side by side bar - absolutely no flex in this - rock solid. Next I got the Losmand D saddle adapter to fit a C9.25 to one of the side saddle bars - excellent rigidity.

What I did next was a total compromise:

1. I put a 127mm MAK in the second side saddle using a pair of the largest Losmandy O rings with 3 point bolted adapters

2. I put the C9.25's original wide Vixen dovetail on top of the scope and used this to connect a Williams Optics 80mm Megrez again using a pair of three point bolted adapters.

These bolted adapters where necessary to align the optical tarins of all three OTAs to the same target, however three slim 2-3 mm diameter bolts are simply not robust enough to hold my smaller two scopes without some differential flexure - probably quite a lot.

It's the aligning the OTA's light path that kills rigidity. The only system I have heard that really works - to align two OTAs correctly yet maintain strict rigidity on both is a Robin Cassidy Tandem Guidescope Aiming Device http://www.robincasady.com/Astro/TGAD.html

They are moderately heavy and cost around $500 landed - but it seems they alone perfectly do the job.

Interested in other folks views. If you want to rigidly mount and align two or more telescopes light paths what other device can you use?

If you had a large SCT and high end mount - you could build a rigid cradle to swaddle the entire OTA and let a second or third OTA be attached to the craddle and light paths perfectly aligned (which would really cost - like high end RCs tend to do).

Hey Matthew that looks the ducks business but a bit out of the price range at the moment, I'll just have to drool over that one.

Originally Posted by Merlin66

IMHO I'd go for a side by side plate..
I mounted my 6" f3.8 and the ED80 on the HEQ5pro...
(I later changed over to Losmanday dovetails..)
A good rigid set-up no issues..

Originally Posted by Irish stargazer

I use the ADM mini dovetail on my C 11 to hold my Megrez 72 and it is rock solid.

Merlin and John, yes I like the side by side look and I think it would be a lot more user friendly without putting the extra weight high up.
The other point I must keep in mind is that these are my first two scopes and I'm not sure where this will all end up so don't want to spend a lot, don't have a lot to spend is the other thing at the moment.
I also like the Idea of the cradle setup, could make one of those without too much trouble.

I have one thing in my favour and that is as a mechanic I have all the tools to make almost any extra bits i need, the only thing I'm short on is a milling machine

Thanks for the input, off to Bintel in the morning so may come home with some bits to get me started.

[Nico13 (Ken)]

Well while at the Bintel shop today to pick up my mount after repairs I had a chance to look at options for the two scopes and wound up with the Losmandy unit but it's the dual fitting one that will take either Size dovetails.
So very happy with that at this stage and it is certainly a rigid plate so I don't think I'll have any problems with flexing and it is so adjustable it will handle future updates without any problems I would think.

Looks like I might get some clear sky tomorrow night with luck to try it out.

Thanks for the input guys.

[g__day (Matthew)]

Ken - what you have done makes a lot of sense - its a great start. What I found difficult is how do you align the two OTAs light path. I started putting the two OTAs in my side by side bars and expected they should be pretty close to aligned - turned out it was too far away to be useable. So the smaller OTA had to become adjustable to match the larger which was locked into a fixed position. And that small amount of adjustable position causes differential flexure.

[Nico13 (Ken)]

Originally Posted by g__day

Ken - what you have done makes a lot of sense - its a great start. What I found difficult is how do you align the two OTAs light path. I started putting the two OTas in mine and expecting they should be pretty close to aligned - turned out it was too far away to be useable, son the smaller OTA had to become adjustable to match the larger which was locked into a fixed position. And that small amount of adjustable position causes differential flexure.

That will be interesting to see how they line up but like you say it's a great start and a good solid point to work from.
I think fine tuning should not be too much of a hassle as I have the tools available to achieve those adjustments.
The ED80 should be here on Tuesday so I will be able to fit both up and see what has to be done.
Wish me luck that I don't have to reinvent it to get it to line up.

[g__day (Matthew)]

Luck wished. Mind you for an 80mm scope you may only have to shift it left / right and up or down by 5 - 10 arc minutes; shims may be able to do that and still give you rock solid stability.