which 2" star diagonal?

[lulu57]

I have a Celestron 8se and my Televue Ethos 13mm does not fit particularly snugly in the 1.25" star diagonal.

It seems to be hanging on by the skin of its teeth.

In another thread (I forget which one) someone recommended that I should get a 2" star diagonal, which will hold the Ethos more securely.

Well, I've been checking them out.

Some cost as little as £60, while the Televue 2" is £240ish. I know you get what you pay for, but what price could I reasonably drop to whilst still retaining a good quality image?

Ta in advance.

[Ben Ritchie]

I have the Astro-Physics MaxBright, which is as good as they come, but - to be honest - I think the differences are probably so subtle as to be invisible. The best buy I ever come across was the William Optics 2" 97% "enhanced reflectivity" diagonal, well made, great value at under £50 used and any differences between 97% and the 99% dielectrics are negligable to the naked eye.

Dielectrics are supposedly more robust for cleaning, but how often do you clean a diagonal anyway?

So i'd suggest avoiding the cheapest, which apparently can show a few issues - I don't know, i've never owned one - but anything reasonably made is fine IMHO.

[lulu57]

Ta for advice.

I think my problem is more difficult than it would seem.

And I think I'm going to have to use idiot language to explain it, so I am preparing to lose all my credibility...

My scope is a Schmidt-Cassegrain, so the part of the diagonal that's going to fit in the scope has to be plastic and threaded. (So far, so lucid).

The difficulty is the eye piece end. My Televue Ethos has one notch cut into it, to fit over one screw on a star diagonal. This works fine on my 4se, because there is only one screw on the in-built star diagonal. However, the 8se has two screws on the star diagonal, so the TV Ethos only fits half way in: I can still secure it with the screws on the Ethos itself, but it isn't very happy.

So, I need to find a 2" star diagonal, adapted for a SCT at the scope end, and with only one screw at the eyepiece end - or the Ethos won't fit.

I've looked at a few, but can not seem to find the Cinderella fit I'm looking for.

There must be a simple answer to this - surely there are loads of people with an 8se and an Ethos who have worked this one out...

I think I'm having a blonde moment...

[Merlin66]

Lulu,

The Meade 2" UHTC diagonal has the SCT thread at the scope side and one screw at the eyepiece end ( at least mine does) Sounds what you're looking for..... Check out the buy and sale pages they usually have one.

[KathGarvey]

Hi LuluI have the WO 2" Dielectric Diagonal, which comes with one screw at the eyepiece end, and comes with the SCT connecter adaptor included.

I got mine from FLO, it is a solid piece of kit

RegardsKath [/]

[ianmwatson]

Hello,

I have a celestron 6" sct and an ethos.

I also have a 2" william optics diagonal, i had to buy a sct screw in adapter though. In my case I removed the visual back it came fitted with and ditched it. Then fitted the diagonal with screw in adapter directly to the rear of the scope (it's what's left when you unscrew the visual back, should be around 2" diameter).

If you haven't already got a 2" diagonal for a refractor or whatever you can buy one ready to go on your sct, as others have said.

Couldn't you just remove one screw from the existing diagonal though? Having said that, you're right to worry about security.

I didn't understand why you said the part had to be plastic.

[John]

Lulu,

Half way down this page:

http://www.scopesnskies.com/second-user-bargains.html

The Antares SCT diagonal is pretty good quality and would do the trick. The non-SCT one would do as well but you would need to use an SCT Thread to 2" push fit adaptor which cost about £15 as well. I've used both types on a Celestron SCT and they work well.

John

PS: Just realised you are using an Ethos - you might want to look for a diagonal with a compression ring fitting - they hold eyepieces more firmly and don't mark them so much. The Telescope House Revelation 2" diagonals are about £80 and have that feature.

J

[lulu57]

What a jolly helpful lot you are - thanks a lot!

[Dangerous-Dave]

I own the 2" Skywatcher Deluxe Di-Electric and it's a nice diagonal, and available at a knock down 88 quid.

If I were you I would get a SCT thread to 2" push-fit adaptor, then you can buy a push-fit diagonal which will work with any type of scope, not just SCTs.

[GazOC]

I agree with Dave, its worth paying a little extra for the flexibility.

[philsail1]

Yes, I agree too - I have a "Williams Optics" 2" diagonal and SCT adapter. This combination will give you that added flexibility with eyepieces, and widely differing fields of view.

Regards,

philsail1

[Tiny]

Telescope House are selling the 2" 99% reflective Revelation dielectric Quartz for under £80.

[Merlin66]

I have both the 2" diagonals and the SCT threaded diagonals. The only problem with the 2" + SCT adaptor is the added back focus. Not a real issue for the optics of a SCT but it does mean that the eyepiece sits much further back and you need to watch the balance and clearance ( on a LX200 fork).

The SCT diagonal sits much tighter on the scope as the thread "locks" the body. Either way they both work.

BTW if you ever get an electronic zero shift focuser #1209 you'll need the 2" fittings!!!

[lulu57]

Yes, I agree too - I have a "Williams Optics" 2" diagonal and SCT adapter. This combination will give you that added flexibility with eyepieces, and widely differing fields of view.

Regards,

philsail1

Ordered one - it's on its way! (to get stuck in the snow...)

[johninderby]

Good move, the thought of an expensive eyepiece like the 13mm Ethos in a little 1.25" diagonal scares me ! Here's a pic of mine in a WO 2" diag. Much better mechanical stability.

John

(click to enlarge)

[lulu57]

Ah yes! It will be mine!! (Imagine demonic laughter here).

[ianmwatson]

I never did find out what the plastic bit was about, oh well it sounds like you got it sorted.

[lulu57]

I never did find out what the plastic bit was about, oh well it sounds like you got it sorted.

I like to maintain an air of mystery.....

Got my lovely WO 2" diagonal today.

Set it up with my TV Ethos. As Keats said, "A thing of beauty is a joy forever."

I'm just going to look at it for a bit.

[Tiny]

You are supposed to look through it - not at it.

But I know what you mean some bits of kit are pure artworks - the only sort we can afford.

[ianmwatson]

I was just about to unintentionally repeat tiny's post. I love my ethos too, and i have the comfort of knowing it cost me 50p more than the scope and mount that's currently attached to it (the C6-S, CG5).

Anyway, I hope you enjoy viewing your new diagonal, I mean the view through your new diagonal.

[lulu57]

Have just put Bristol's stockpile of salt on my backyard.

Am determined to get out tonight and use my new toy.

(You watch it cloud over).

[lulu57]

I played with my new toy tonight.

I'm quite besotted.

[John]

I played with my new toy tonight.

I'm quite besotted.

Careful Lulu - you are showing signs of becoming an equipment junkie - like me .

So it was YOU who used up the road salt in the Bristol area was it ????. No wonder the side roads around me (Portishead) are such a mess !.

Seriously, it's amazing how you develop a "taste" for quality equipment - the Tele Vue stuff is just so nice - that black and green livery, the multi-coatings, the "heft" of the things - fortunately they don't just look nice - the Naglers and Ethos (Ethi ?) are stunning pieces of kit - just wait until you get the great globular cluster M13 in the Ethos with your C8 SCT - mind blowing :shock: .

John