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Equipment Discussions >> Mounts

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russell23
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Reged: 05/31/09

Loc: Upstate NY
Largest Refractor that a Vixen Super Polaris ... new
      #4469499 - 03/23/11 07:57 PM

What is the largest refractor you would put on a Vixen SuperPolaris mount? I have a Vixen SuperPolaris that I use in Alt-Azimuth mode. I have it on an Al Canarelli tripod.

I used a 120mm f/8.3 achromat on it ~10 lbs and 1000mm FL. Currently I'm using a 140mm Vixen Neo-achro on it. The mount handles it fine once I get it the scope focused. The problem is that it is somewhat difficult to focus the scope because of vibrations while focusing - with both the 140mm and the 120mm f/8.

So how small would I have to go to match a scope to this mount that would not have huge vibration problems while focusing?

A 110 f/7 ED doublet?

A 102mm f/7 ED doublet?

Dave


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Eddgie
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Reged: 02/01/06

Re: Largest Refractor that a Vixen Super Polaris ... new [Re: russell23]
      #4469627 - 03/23/11 08:54 PM

Kind of hard to answer because everyone's tolerance for shaking is a bit different.

I use a Vixen 100ED f/9 on the old Polaris and it works well enough for me.

I used a Vixen 140 on a CG5 with Vixen HAL 110 legs and it worked for me too though, but mostly because I used that scope at lower powers for wide field viewing.

Before that, I had it on a Losmandy GM8 and this was a MUCH better mount for that scope.

So, on the stanard SP, I would think you would not have to go SMALLER than a 100ED, but my guess is that a 110 would work just as well.

A big mount on a refractor is a pleasure to use. My 6" APO only weighs 28 lbs or so, but I have it on a giant Meade LXD750 and it is the first mount that I have ever owned that I though was capable of holding a 6" refractor to my satisfaction for high power work.

So, it is highly variable. My guess though is you probably need to be at a 100 or 110mm scope.


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Jeff Morgan
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Re: Largest Refractor that a Vixen Super Polaris ... new [Re: russell23]
      #4469646 - 03/23/11 09:04 PM

You might be happier with the mount if you put a Hargreaves strut on it.

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7331Peg
Sirius Observer
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Reged: 09/01/08

Loc: North coast of Oregon
Re: Largest Refractor that a Vixen Super Polaris ... new [Re: Jeff Morgan]
      #4470079 - 03/24/11 12:35 AM

You might also try switching it over to EQ mode. I noticed a few nights ago I was getting quite a bit of vibration in alt-az mode on that mount using an 80mm f15 - and that was even with a weight on the other side to offset the weight of the scope. I switched to EQ and that took care of most of the eyepiece vibration.


John


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John Carruthers
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Re: Largest Refractor that a Vixen Super Polaris ... new [Re: russell23]
      #4470226 - 03/24/11 04:37 AM

I have a 127mm F9.4 on my SP, it struggles unless carefully balanced. With the 102mm f6 it works very well.
The chap who gave it to me had a 10" f5 reflector on it :-)


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SteveG
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Re: Largest Refractor that a Vixen Super Polaris ... new [Re: John Carruthers]
      #4470954 - 03/24/11 12:47 PM

I've had an SP mount for 22 years, and a GP (Similar) for about 3 years. Both of these mounts will easily handle a 20 lb scope given they are on a good tripod - NOT the wood or aluminum tripod they come with.

I mounted my 6" f8 reflector on an SP with home-made fixed height legs with excellent results - less than 2 sec damp time.

I mounted my ED-110 on a SP mount with a surveyors tripod with even better results - less than 1 sec damp time.

I currently have an ED 120 (17 lbs with rings, diagonal and 2" eyepiece) mounted on my GP with the surveyors tripod. This is a much longer scope, but the mount is still very stable - damp time is under 2 sec when bumped.

The SP is an excellent EQ head, when attached to a good tripod. There is a cheaper alternative tripod that gets really good reviews available at Hands on Optics:
http://handsonoptics.com/index.php?main_page=product_info&cPath=1_74&products_id=881


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orlyandico
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Loc: Singapore
Re: Largest Refractor that a Vixen Super Polaris ... new [Re: SteveG]
      #4472580 - 03/25/11 02:26 AM

I think "easily handle a 20lb scope" is a bit much.

I've had a 22lb C9.25 on my GP several times and it ain't happy. Consider that the C9.25 is quite short.


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russell23
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Re: Largest Refractor that a Vixen Super Polaris ... new [Re: orlyandico]
      #4473144 - 03/25/11 10:58 AM

Thanks for the feedback everyone. This summer I might try building a Hargreaves strut. But I'm a little concerned that the problem is where the tripod legs join the base of the mount. When I've set it up in daytime to check out the source of the vibrations it seems that there is some flex between the base of the mount and the tripod legs. I don't know if a Hargreaves strut would help with that.

I do know that this flexing I see does not happen when I do not have the Vixen 140 on the mount. So I'm thinking that extra weight is a problem. I have two counterweights on it so that helps a little.

Dave


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Jeff B
Carpal Tunnel
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Reged: 12/30/06

Re: Largest Refractor that a Vixen Super Polaris ... new [Re: russell23]
      #4473296 - 03/25/11 12:08 PM

I love my SP and GP mounts. Like what others have said, the tripod is the limiting feature. I've had very good results with a good old Mead LDX-75 tripod. The GP & SP fit it like a glove, they are plentiful and, the best part, they're cheap on the used market.

So configured, my SP and a Meade 5" F9 were a very effective combination which damped out vibrations very quickly and focusing at high power was no problem at all.

Jeff


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SteveG
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Re: Largest Refractor that a Vixen Super Polaris ... new [Re: orlyandico]
      #4473453 - 03/25/11 01:16 PM

Quote:

I think "easily handle a 20lb scope" is a bit much.

I've had a 22lb C9.25 on my GP several times and it ain't happy. Consider that the C9.25 is quite short.




My 17 lb set up with it's long tube rides nicely on this mount. Were you using the stock tripod?


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SteveG
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Re: Largest Refractor that a Vixen Super Polaris ... new [Re: SteveG]
      #4473506 - 03/25/11 01:33 PM

Here's a tripod that would be much more stable - $100:

http://www.astromart.com/classifieds/details.asp?classified_id=725584


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russell23
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Loc: Upstate NY
Re: Largest Refractor that a Vixen Super Polaris ... new [Re: SteveG]
      #4474053 - 03/25/11 05:54 PM

Quote:

Here's a tripod that would be much more stable - $100:

http://www.astromart.com/classifieds/details.asp?classified_id=725584




Steve, Do you think that tripod would be more stable than one of these which I currently have it on:

http://www.alsastro.com/

I'm really happy with this tripod - very well built, but as I said, I do think the major source of the vibrations is the legs flexing a bit where they join the base of the SP mount.
Dave


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SteveG
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Loc: Seattle, WA
Re: Largest Refractor that a Vixen Super Polaris ... new [Re: russell23]
      #4480442 - 03/28/11 07:08 PM

Quote:

Quote:

Here's a tripod that would be much more stable - $100:

http://www.astromart.com/classifieds/details.asp?classified_id=725584




Steve, Do you think that tripod would be more stable than one of these which I currently have it on:

http://www.alsastro.com/

I'm really happy with this tripod - very well built, but as I said, I do think the major source of the vibrations is the legs flexing a bit where they join the base of the SP mount.
Dave




Yes - the hub is where all of the flex happens. You'll notice that the leg attach point is very wide on a good tripod. The steel tube and surveyors tripods are very rigid.
Those legs you have a very nice but because of the way they mount they are really not much more stable. You'll notice the Orange tripod from Hands On Optics has a solid block of wood between the tops of the legs which is what makes that one better.


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Geo.
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Reged: 10/01/08

Loc: Upstate NY
Re: Largest Refractor that a Vixen Super Polaris ... new [Re: SteveG]
      #4480890 - 03/28/11 10:31 PM

The C9.25 is as long as a C11 and weighs 5 pounds less than the CF C11. The C11 is terrible on the CG-5, which is a *BLEEP* child of the SP. I wouldn't sell a C9.25 to anyone (well maybe a couple of people I can think of) on a CG-5. The C9.25 needs a G-9 (on a G8 or 11 tripod), a GP-DX (D2), a HEQ-5 or 6.

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SteveG
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Re: Largest Refractor that a Vixen Super Polaris ... [Re: Geo.]
      #4482253 - 03/29/11 01:28 PM Attachment (85 downloads)

I had 3rd light with my GP mounted 120 the other night. Stability is not going to be an issue - it is rock solid thanks to the surveyors tripod.

Here's my SP mount on the surveyors tripod - the scope is a 110.


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