Would love some advice on diagonals...

[Stratis]

Hi, first post on this forum so on my best behaviour

I've recently got back into the hobby after waking up and realising I wasn't so poor anymore.... I've been writing some equipment reviews on my experiences for this site, hopefully have those posted in a few days. I'm the proud owner of an Aquila ST80, a SkyWatcher 127 and now finally the ubiquitous C9.25 SCT, purchased from a member of this very forum!

The C9.25 is on my HEQ-5 and I couldn't be happier with it.... once I figured out that the previous owner had rotated the secondary 180deg out of phase anyway. Once that was put right and collimation achieved, the scope has given me views I could barely have imagined and is quiet enough on the HEQ5 to run next to my neighbour's open window without waking anybody up. I'm thrilled to bits with it , and with the f/6.3 focal reducer the views are so sharp and bright it's hard to believe.... I've literally just come from observing Jupiter and even in a 15mm UWA it was gorgeous.

My new problem is field of view; I only have 1.25" eyepieces of varying (sub-£60) quality, and plan to begin replacing them steadily with 2" equivalents, but before I can do this I need a solid SCT-fit 2" diagonal. There are so many options even within this narrow bracket that I am genuinely mystified as to how to proceed, and it isn't something I'd like to get wrong.

To be clear; price is not exactly an object, as long as the extra cash is well invested. A TeleVue Everbrite is £280-ish and I'd happily spend that if someone who's used one can assure me of the value of it. At the moment I'm looking at two general upgrade paths;

• Go Expensive; there are a wide range of models between £100 and £150 from Williams Optics, TS and Antares all with dielectric coatings.
  
• Go Premium; this naturally means seeking out a Denkmeier, Baader, AP or (gasp) TeleVue. From what I can gather I will pay upwards of £200-£300 for these.
  

My dilemma, and I would prefer genuine field experience to conjecture, is the genuine improvement that the premiums offer in terms of image quality. I would like, for the moment, to exclude the concept of vignetting from the decision as I may very well be using a bigger scope this time next year and the rear aperture of the 9.25" may not be an issue forever. Do the premium diagonals truly offer wider FoV/better viewing than the still rather expensive conventional brands? I have read comments that the cheaper diagonals, despite their premium construction, suffer from internal field stoppage that limits their effectiveness against the Everbrite and MaxBrights of the world... is there any truth to this?

I would very greatly appreciate some guidance from people who've used these diagonals.... is it worth sinking the extra hundred into the purchase or are they just prestige pieces?

[Stratis]

Oops, forgot to put; whichever option, are there any particular brands/models that come well recommended over the others in the group?

[Rockrae78]

I have the Williams Optics dialectic diagonal with SCT adapter (bought from FLO for £115) and I couldn't be happier with it.

It's very solidly built. The diagonal that came with my CPC800 is IMO very flimsy and I always felt a bit worried when using my (fairly hefty) Baader Hyperion EPs with it. The WO diagonal is really sturdy and takes the weight of the EPs with ease. I've even tried it with a 2" Barlow and Baader Hyperion EP and again, no problem dealing with the weight.

I must admit though, I don't use the SCT adapter. It doesn't seem to fit flush and makes a horrible noise when attaching it to the scope. I bought a Baader 2" click-stop CL-SC clamp to use with it instead.

http://www.harrisontelescopes.co.uk/cgi-bin/sh000001.pl?WD=click%20baader&PN=Baader_2_ClickLock_CL%2dSC%2dClamp%2ehtml#a2956220

This does add more length onto the back, but there is still enough clearance on my scope but you may want to check the clearance space on your scope to make sure it will all fit.

HTH.

[Grotemobile]

I just think they are just prestige pieces.

http://www.firstligh...r-diagonal.html

These are just as good.I dont think you will notice

any difference through this, or one costing double

the price.

Steve.

[Pig]

There is loads of room on my 925 for a 2" diagonal even with the Baader Steeltrack fully extended there is still around 22mm clearance.

[Mark in Macc]

I would second using the Baader Clicklock system as a visual back and getting a pushfit diagonal. As you are using an equatorial mount, the position of the eyepiece will end up all over the place and you will end up constantly unscrewing the SCT fit to reposition the diagonal/eyepiece. The Clicklock system makes this so much easier. I bought an Ascension dielectric diagonal from Opticstar for £80 and have been very happy with it. It copes very well with my 2" Explore Scientific monsters.

[John]

I have a Tele Vue Everbright 2" and a Revelation 2" Dielectric Quartz which is the same diagonal as Pig pictures above. The Tele Vue retails at £241 and the Revelation at £97. I've owned them both for a couple of years now and I really cannot tell the diffference between them optically. Mechanically the Tele Vue is machined from a single block of alloy and finished to a higher standard.

Having used lots of diagonal types over the years it's one area where I don't feel investing in the ultra premium types brings any tangible performance benefits. £100 or so will get you something that will do an excellent job for you.

[Wolfgangwand]

I have and use both the WO 2" Carbon diagonal and TV 2" Everbright and can find no difference in performance visually . I did think the TV gave a slightly more natural light but im quite sure that i thought that way purely because i had read so . IMO visually the WO is superb and i would not pay for the TV for this alone.

[Stratis]

Thank you all so much for the advice, there's no substitute for people actually having the kit!

I'm glad to hear there are no apparent issues with the WO diagonals, think that may well be my next addition. A Crayford of some description would also be nice, was concerned about backfocus on the 925 but I guess that isn't an issue? Focusing has been difficult with this scope for some reason, 'sneaking up' seems to involve 1/16th or 1/32nd turns of the focus knob on planetary targets which can be a real chore so perhaps I'll chuck a dual-speed in there.

Has nobody ever noticed FoV reduction then? I'm hoping the answer is no as it could potentially save me £150

[Clockwork_Orange]

For whats its worth if you choose to go down the Revelation route, Telescope House are doing the 2" Dielectric at the moment at £99 and throwing in a Meade 30mm QX.

Its in the Mega Deals section.

Regards

John

[Stratis]

For whats its worth if you choose to go down the Revelation route, Telescope House are doing the 2" Dielectric at the moment at £99 and throwing in a Meade 30mm QX.

Gentlemen.... if you'll excuse me....

[Rockrae78]

Ahem... I'm a lady don't you know!

Well, I'm female at least... Perhaps not so ladylike!

[Wolfgangwand]

I've noticed no reduction with FOV although I can't say I was particularly looking for any , would imagine it to be minuscule and how you frame /choose magnification of target. Like most things with this hobbies equipment there's ALWAYS an item slightly better but at what cost . Don't worry though with these diagonals you'll be on to a winner.

[Stratis]

Ahem... I'm a lady don't you know!

Well, I'm female at least... Perhaps not so ladylike!

My sincerest apologies, I do tend to assume that anyone carrying a tube around is a man

I think I understand why Telescope House are offering the QX eyepiece with the diagonal...

http://www.astromart.com/articles/article.asp?article_id=564

A great many seem to consider the 26mm and 30mm QX line to be among the worst eyepieces ever made! I'm still grateful to Clockwork_Orange for the post and it remains an amazing deal... nothing beats free after all... but it's clear that the QX in anything shorter than f/10 won't cut a lot of ice. This precludes my ST80, my 127 can't accept 2" EPs and the 9.25" won't be able to use the focal reducer. Still... might consider throwing it onto fleabay to recoup some costs...

Does anyone have any hard data on the internal field stoppage of these 2" diagonals?

[lardy]

I have a Tele Vue Everbright 2" and a Revelation 2" Dielectric Quartz which is the same diagonal as Pig pictures above. The Tele Vue retails at £241 and the Revelation at £97. I've owned them both for a couple of years now and I really cannot tell the diffference between them optically. Mechanically the Tele Vue is machined from a single block of alloy and finished to a higher standard.

Posted by John

I'm with John on this ... I too have the Everbright and the Revelation and the Revelation gets my thumbs up

Mark

[Rockrae78]

My sincerest apologies, I do tend to assume that anyone carrying a tube around is a man

I get that a lot! Especially with a name like Rae!

[kerrylewis]

I get the opposite being male and coked Kerry most people assume it's a female only name!

BTW I have the WO 2" diagonal with my 925 as recommended by FLO but I have not done any comparisons. Very happy with it though

Kerry

[kerrylewis]

Called not coked!

[Pig]

Thank you all so much for the advice, there's no substitute for people actually having the kit!

Focusing has been difficult with this scope for some reason, 'sneaking up' seems to involve 1/16th or 1/32nd turns of the focus knob on planetary targets which can be a real chore so perhaps I'll chuck a dual-speed in there.

Has nobody ever noticed FoV reduction then? I'm hoping the answer is no as it could potentially save me £150

A dual speed focuser was one of my best investments, mine certainly helps to hit that sweet spot better than any other piece of equipment

[Pig]

Called not coked!

Very scary mistake to make only one letter away from oblivion

[kerrylewis]

I also invested in the Motofocus. I think that they are perhaps overpriced for what they do but the ability to adjust focus without touching the scope is a great advantage especially when trying to get the best out of a planet view.

Carefully checking that the spellchecker has not misinterpreted my dodgy typing

[Stratis]

Wow.... so my shopping list for the weekend has expanded thanks to all this great advice.

So I'm looking at the Revelation push-fit 2" quartz-dielectric (plus that QX eyepiece from Telescope House), Starlight Microfocuser if my sodastream-cap mod somehow doesn't revolutionise backyard astronomy, and a solid SCT adapter (Baader Clicklock probably) to stop my binoviewers falling out.

Still vaguely tempted by the WIlliams Optics carbon on FLO, but it's £115 and I can't work out why.

[Pig]

Wow.... so my shopping list for the weekend has expanded thanks to all this great advice.

So I'm looking at the Revelation push-fit 2" quartz-dielectric (plus that QX eyepiece from Telescope House), Starlight Microfocuser if my sodastream-cap mod somehow doesn't revolutionise backyard astronomy, and a solid SCT adapter (Baader Clicklock probably) to stop my binoviewers falling out.

Still vaguely tempted by the WIlliams Optics carbon on FLO, but it's £115 and I can't work out why.

It is because it is a very good looking Diagonal, it has the bling factor I was going to get one but there was no stock anywhere at the time

[Stratis]

It is because it is a very good looking Diagonal, it has the bling factor I was going to get one but there was no stock anywhere at the time

My only concern with it is the added focal length on the WO.... the Revelation seems shorter.

[John]

My only concern with it is the added focal length on the WO.... the Revelation seems shorter.

Not enough difference to trouble an SCT I would have thought - they have lots of focus travel.