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Which mount for a 114 OTA?

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#1 astrowolf67

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Posted 10 August 2009 - 09:31 PM

First off, a little back ground. A while back, I acquired a mint condition Towa mount, with a 114 clam shell. In my quest for a 114 OTA to go with it, I bought one, thinking it was a modern light weight version made in China. What I ended up with was a Meade 114NT, which appears to originally have been mated with an LXD500 mount. This OTA is much better quality than I expected, and as a result, heavier. I mounted it to the Towa mount (EQ2), and, quickly realized it is not going to be stable enough. Would an Orion Astroview, or similar EQ3 be sturdy enough for this particular OTA? It's going to be for visual use only.

Thanks!

#2 deSitter

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Posted 11 August 2009 - 05:17 PM

Yes the Astroview is far more mount than required by that OTA, which weighs all of 6 pounds. The old style EQ2-class mount, the one with "fins" to stiffen the axes, is what I use and it's more than enough. The Astroview will convert this from G&G to just another heavy PITA to set up telescope, which sort of ruins its charm.

BTW I have the same OTA - I replaced the secondary with a quality unit and the resulting scope is outstanding optically - see video here:

http://www.youtube.c...h?v=qPw-2stFJhE

-drl

#3 Nordmann61

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Posted 11 August 2009 - 06:47 PM

I would suggest a EQ3-2, it have a max. load of about 5,5 Kg, or about 12 lb. A 114mm OTA should be well within that weight.
Concider buying the new version of the EQ3-2, the NEQ3-2, it has a dovetail receiver as standard, much more convenient. On the standard EQ3 a dovetail saddleplate must be fitted I think.
If you want, it can, as the standard EQ3, be upgraded with GoTo, single axis or double axis motor drives and polar scope.
I have had my NEQ3-2 for a few months now, and I am very satisfied with it, good fit and finish, nice white paint, quality setting circles, overall good quality. Very stable mount for reflectors up to 130mm aperture, and stable even for short focal-lenght 150mm reflectors for visual use.
I recommend it highly, very stable for my 130mm reflector. I mostly use it with my 90mm refractor.
Kind regards,
Nordmann61.

#4 Gord

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Posted 12 August 2009 - 08:51 AM

I too would recommend the EQ3, either the older version, or the new NEQ3 that allows the Vixen style bars. I have a Tasco 11TR that came on the EQ2. It will hold the scope and is completely usable, but I like more stability. I find the 11TR on the EQ2 to be sort of like using my C10N on the EQ5, what most consider a total no-no.

Personally, I think the ultimate model for this setup is that of the old Celestron C4.5 (the Vixen sourced one). It used the Vixen Polaris mount, which the EQ3 is a newer clone. I think this is a perfect balance of stability and portability.

That's the mount I was aiming for when re-working my Tasco, but didn't have one. Instead I used the CG5a I had. This is much more significant mount, one that carries my C10N.

Posted Image

Definitely not a one handed grab-n-go type setup, but the ultimate in stability. I personally find the size of the 4.5" f8 tube to be big enough that it's not in the same portability class as an 80mm refractor for example. But then, it has a whole lot more performance than a small refractor, so it really should be compared to the 4-5" class refractors. They aren't so portable either.

Ultimately it's all a personal decision as to what you find acceptable in terms of stability, and what you are willing to lug around. I feel I want more than what an EQ2 can offer, and the difference between the EQ3 and EQ5 in terms of bulk isn't that much. I may eventually try to find an EQ3 specifically for mine, but I do really like the stability of the EQ5.

Clear skies,

-Gord

#5 astrowolf67

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Posted 12 August 2009 - 08:18 PM

Thanks for all the help and assurance of the EQ3 compatability.

Gord, very nice set up! I've always liked the Tasco 11T's.

deSitter, excellent video, and, may I ask, why the change in the secondary?

#6 deSitter

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Posted 13 August 2009 - 02:24 PM

astrowolf,

I bought it on an impulsive whim from the Meade outlet store because it was cheaper than buying tube rings! All I wanted were the rings for my 5" refractor (to attach a side scope). Looking through it, I saw that it was astigmatic but "something told me" there was more to the story - the diffraction pattern looked perfect other than being oval. Hmm, could be the secondary, so I decided to gamble on replacing it - and a miracle occurred - the scope is as good as any 4.5" reflector can be and I would not hesitate to put it up against a premium 4" refractor - now it would be trounced mechanically and esthetically but optically it would be hard to choose. It's possible to make a spherical mirror of great smoothness and accuracy. I love the little guy and would not sell it for 10 times what I paid for it.

I bought the replacement diagonal (1.1") from Hands On Optics - I believe the make is Antares.

-drl

#7 astrowolf67

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Posted 13 August 2009 - 06:55 PM

deSitter,
Thanks again for more input. I've not had a chance to get first light with mine, but, will check it over good when I do. One more question, what size are the screws that fit the mounting rings? I assumed 1/4-20, but, after trying one, it seems it might be a metric size.

Thanks!

#8 deSitter

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Posted 13 August 2009 - 07:03 PM

Everything is metric - these were sold in Europe. I don't remember about the rings as I drilled them out - I'm going to say M6.

-drl






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