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Star Diagonal Recommendations?


Ian McCallum
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Have just got myself my first refractor (that plastic one I got as a kid for Xmas, doesn't count), can anyone recommend a decent star diagonal, that doesn't break the bank? 🤔

It's for a SW Evostar 120 (not ED). I have one 2" 28mm LET eyepiece, so don't know if it's worth paying for the extra ability to use the 2" or would a 1.25" diagonal do mean? 

I mostly use BST StarGuider ED eyepieces. 

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I really like the GSO 2" dielectric diagonals.  I don't think the quartz upgrade makes any difference that I can see (I have both versions).  I really like their zero added height 1.25" adapter.  If your 1.25" and 2" eyepieces all focus at or near their shoulders, then this really speeds up switching between them because of minimal refocusing.  The casing is built like a tank, so flexure isn't an issue even with the heaviest 2" eyepieces.

I believe they are sold as Revelation Astro in the UK as well as TPO in the US.

Edited by Louis D
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You may or may not have realized that you can get both mirror and prism diagonals.

The second recommendation above is a decent prism (I have that one, I use Starguiders too, and the diagonal is probably at least as good as the rest of my kit). The first recommendation is a mirror diagonal. I doubt that you could beat that price for a dielectric mirror (dielectrics are superior to the ones supplied with most scopes), and Svbony kit is generally good.

I believe your Evostar is F8, so if you've not already done so, you might want to browse some of the discussions on the relative merits of prisms and mirrors:

https://stargazerslounge.com/topic/385303-prism-or-mirror-diagonal-at-f77/#comment-4160040

https://stargazerslounge.com/topic/384289-opinions-on-prismmirror-diagonals/#comment-4149690

 

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1 hour ago, johninderby said:

That looks a steal at £49.99...

I like my red Altair Lightwave but it's £20 more and tbh I'm increasingly sceptical paying more for premium branded dielectric diagonals actually gets you more performance... I also have a Skywatcher. It does the job in the 102 Skymax.

 

Edited by ScouseSpaceCadet
£20
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I had the same scope and the 6" f/8 version and I used the 2" Skywatcher Dielectric mirror diagonal (the same one that comes with the SW ED scopes) with them and it worked great. The altair 1.25" premium diagonal is very good as well for under £70. The Tak Prism 1,25" is excellent as mentioned above but my favourite with refractors at the moment is the Baader T2 90deg prism, it costs about £75 but you also need to get a nosepiece and eyepiece holder. If you're on a budget and not that bothered about using the 2" eyepiece you have, I would just get a Skywatcher 1.25" Dielectric diagonal which retail around £50, I've seen them being sold used for around £35.

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10 minutes ago, Franklin said:

I stand corrected, cheers John. If they've gone up that much you could get the Baader. Although they've probably gone up as well?

Some of the SW stuff is now going for silly prices. The Baader prism hasn’t gone up much so may be a good time to buy one.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p604_T2-diagonal-prism-90----T2---1-25--connection-on-both-sides.html

Edited by johninderby
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You get a lot of add-on options with the Baader range, but they're more expensive than that Svbony.

2 hours ago, Zermelo said:

I doubt that you could beat that price for a dielectric mirror

OK, I've now seen that the "similar items" section at the bottom of that Amazon listing includes some that claim to be dielectrics for less than the Svbony, from brands I'm not familiar with. But personally I wouldn't take the chance, whereas I would be happy with the Svbony. As @ScouseSpaceCadet says, it's good value with the way prices have risen over the last year or two.

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7 hours ago, Zermelo said:

I'll have to check my $50 2" dielectric Amazon diagonal against that one.  The biggest problem with it is that the 2" compression ring is mounted too high and forces eyepieces with undercuts up at an angle.  Otherwise, it works just fine.

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