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new star diagonal for achromatic

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#1 lamplight

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Posted 15 November 2012 - 08:07 PM

hi

so the 1.25" diagonal in my used xlt 102 is all scratched up on the tube and slips around too easy.. I bought an orion dialectic 99% for my sct and am happy wi it. I was planning on getting an orion 2" 99% reflective dialectic coating right angle as a replacement so ill have flexibility with 2" or 1.25" eyepieces. the price is right the specs are right , just want to see if I might be missing anything before I get it.. ie: are any of the other brands worth twice the cost? any certain features good for this type of scope? should I get a 45 deg instead of 90 deg? just want to make sure I get the right thing.

#2 Paco_Grande

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Posted 15 November 2012 - 09:51 PM

No on the 45 degree. Those are best for terrestrial viewing and hard to use once you begin to point well into the sky, and worthless at zenith. Think about it. You'll be laying on the ground, all twisted around and stuff and wondering, "what the heck was I thinking?"

I bought a 1.25" 90 degree Williams Optics from Agena and it meows like a happy kitty cat. I think you're good with the Orion, though!


#3 GOLGO13

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Posted 15 November 2012 - 10:04 PM

Without a doubt get a 2 inch 90 degree. Enhanced or dielectric should be fine. Suggest one with a compression ring vice just a screw. should be $100-150 if you go dielectric. The GSO ones are $100 at AgenaAstro.

#4 Jon Isaacs

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Posted 16 November 2012 - 05:38 AM

Without a doubt get a 2 inch 90 degree. Enhanced or dielectric should be fine. Suggest one with a compression ring vice just a screw. should be $100-150 if you go dielectric. The GSO ones are $100 at AgenaAstro.


A 2 inch diagonal is definitely worthwhile, with the right eyepiece it'll provide a 2.4 degree field of view in an 4 inch F/10. GSO makes them for various vendors, Agena is a good place to buy.

As far as the 45 degree diagonal, these are correct image diagonals and use a complicated roof prism that has a complicated light path, at high powers they are generally perform poorly.

Jon

#5 lamplight

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Posted 16 November 2012 - 07:38 AM

ok thanks everyone.. I've seen the gso model.cheaper, yes.. sounds like the orion it is, with higher reeflectivity and all. it does have the compression ring and a single knob like the one on my 1.25" which I agree is waaaaay better. great. now to figure how to pay for it. :)

Jon you are talking about the gso's using the prism right? the orion doesn't say that and I assumed the dielectric coatings was specifically for mirrors which offered more light transmission than prisms I thought I read. the orion doesn't say anything about being correct image and neither did the 1.25" version of the same thing.. YET I found it provided a right side up image but was still reverse... but dialectric mirrors and no prisms.. so once again my questions have questions. ?

so I did just see the Williams which has all the same features at about the same price 135. might try that one..actually a couple dollars cheaper than the orion. if it doesn't say I thought I'd assume its not correct image, (?)

on the agena site I see that all the "correct image" diagonals are prisms so that makes sense.

regarding the 45 vs 90* question, yes I setup the scope Sunday night I think It was and didn't extend the tripod legs (habit from using the C10 reflector) and yes I was literally on the ground a lot.. I'm just getting used to all this new stuff.. thought it'd ask just in case there was something else I didn't know I didn't know. :p

#6 lamplight

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Posted 16 November 2012 - 08:06 AM

Williams options 99% dialectic RA with 1.25" adapter comes in two favors: quartz which supposedly offers finer polishing accuracy for $200, or $135 for the one without quartz but also 99% reflectivity dialectic coating.


would I notice the quartz quality with this achromatic refractor ?

would I notice it if I later upgraded to an APO refractor? (I know, that's crazy talk.. what! me? upgrade? )

thanks so much !

#7 lamplight

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Posted 17 November 2012 - 11:35 AM

the GSO quartz dielectric only $120! are they good qualit or better off with Williams or orion ?TY :)

#8 lamplight

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Posted 19 November 2012 - 05:01 PM

well i ordered the gso 2" with dialectric quartz as the price was just awesome.. we'll see how it is quality wise!

#9 Paco_Grande

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Posted 19 November 2012 - 07:26 PM

The GSO Should be excellent.

#10 lamplight

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Posted 19 November 2012 - 10:20 PM

I hope so.. I've read they are they make many of the other brands..thanks paco Phil :)






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