Diagonal Upgrade??

[ashworthacca]

Hi all, I have a Celestron Nexstar 5SE and was wondering if I should upgrade the supplied diagonal and if so what do you recommend?

I do like to use the scope on occasion for terrestrial viewing so one that corrects the view would be welcome.....do they do these?

I'm still pretty new to this so any guidance on which to consider and also what improvements this would bring would be much appreciated.

Regards

[MartinB]

Of all the upgrades possible changing the diagonal would probably be bottom of my list. I have used a Celestron diagonal supplied with an NS8 and found no improvement in view when I compared it with a premium William Optics one. I'm sure, if you worked really hard, you could tell a differennce in contrast and observable detail with a televue with fancy coatings and a basic model but not worth the £££s IMHO.

The ones with dialectric mirrors are more durable and may be worth getting if you haven't already got a diagonal. Brass compression rings are nicer to use than simple fixing screws to hold the EP.

You need an erecting prism if you want to fully correct the orientation. Mirror diagonals turn the image the right way up but left and right are still reversed. I don't know whether transmission is as good as the mirror varieties. For terrestial use a 45 degree design may be a more comfortable option.

[ashworthacca]

Thanks Martin, I think I may now just look to get a 45 degree erecting prism diagonal just for terrestrial viewing.

Many thanks

[Mark at Beaufort]

I have used an erecting diagonal on a 5" Nexstar in the past and the view of the night sky is not quite as good than with a standard star diagonal. In saying that sometimes an erecting diagonal can be helpful, especially if you are a beginner and trying to relate the sky through the EP in comparison to a sky map. In these cases an erecting diagonal can be a real bonus. Its just a matter of whether you purchase the 45 or 90 degree diagonal, and as already stated for terrestrial viewing, 45 degrees would be better. I think William Optics make a reasonable 45 degree erecting diagonal.

Mark

[ashworthacca]

Thanks Mark....that's interesting about the view of the night sky with an erecting diagonal not being as good as a standard one. Is there a specific reason this would be the case?

[Rossco72]

The Prism has more surfaces and more coatings for the light path to go through. With a good quality one, most of us would probably not notice but I believe it is just a matter of physics and the path the light has to take.

[Bigwings]

Is the supplied diagonal a prism of a mirror and what is the f number of the scope,if its f10 then you might as well stay with the prism if thats what it is.

[ashworthacca]

Is the supplied diagonal a prism of a mirror and what is the f number of the scope,if its f10 then you might as well stay with the prism if thats what it is.

Honestly don't know but yes the scope is f10.

[Bigwings]

I have an SE8 and that has a prism. It doesn't deteriorate like a mirror and just needs cleaning from time to time.

At f10 the color problems of the prism are not a problem which it would be on an f6 and below. I think you could better spend your dosh on something better than upgrading your prism diagonal if that's what it is.

David Hinds will be able to tell you what the scope comes with.

Clear skies

Mike

[ashworthacca]

Thanks Mike.

[Peter Drew]

I've just returned home from Tenerife where I had great views of Mars with a 8SE at 450X using the supplied prism diagonal so I wouldn't expect much improvement with an alternative. I also have a 45 degree erecting diagonal for terrestrial viewing. The standard 90 degree diagonal will give you an erect image but left to right reversal, the 45 uses a roof prism and will be fully image corrected. It is the difficulty of making a good roof prism that detracts slightly when used astronomically. A good one would cost lots!

[Jupiter Martin]

As said not really much point in upgrading. The supplied Diagonal will on average reflect 94% - 97% of light. A dialectic Diagonal will only increase this to 99%. You would be much better of upgrading your EP and a good set of filters IMHO

[ashworthacca]

yep...now well and truly convinced, my cash needs spending elsewhere.

Thanks for the help guys.

[ahlberto]

I have bougth a denkmeier S2 diagonal and was one of the best buys i ever made.Very good mecanic and yes,they are better visualy than the stock suplied.The compression rings are a must sice i dont like to have mi eyepieces marked with scratches.A william optics 2" dielectric diagonal isnt so exensive and is a good upgrade for a C8,for example.

[ahlberto]

I dont like to see mi answers censured by the moderators.If you dont like just erase all the reply,but dont censure or modify,please.This is gestapo behavor