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Thread: Telescope, 2" diagonal vs 1.25 diagonal on an 8" NexStar SE SCT. Big advantage?

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    HokieScope's Avatar
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    Default Telescope, 2" diagonal vs 1.25 diagonal on an 8" NexStar SE SCT. Big advantage?



    Getting ready to buy the 8" NexStar SCT and want to determine the best accessories.

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    olegvj's Avatar
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    I have this wonderful 8SE and have invested in 1.25" filters etc. It has very sharp focus and all, but I disliked its stock diagonal because it is a big piece of glass (prism!) and creates blue/red bands around bright objects when in slight disallign.
    I have read all those hyper-puper-hilarious 5-star reviews about William Optics 1.25 diagonal and put my money into it. AND, voila!

    Oosh.. when I got my 1.25 William diagonal.. I greatly stunned with disappointment and sisbelief of this poorly constructed pice of shit. I am myself an engineer and certainly would have thrown away if I would construct such a junk!
    1. It has FAR FAR FAR long barrels, so with any filter screwed to the input barrel it will HIT (REALLY, HIT!!!) the glass of the Celestreon focal reducer!!! This is INCREADIBLE!!
    2. Its output barrel is about 5 mm longer than Celestron stock diadonal (see 1. - I have to screw input barrel another 5 mm further to not hit the glass.. NUISANCE! BAD! BAD! BAD! Willam Optics!!)
    So, I have to screw my main mirror FAR FAR FAR away of its normal position to attain any focus. I am sure that such off-normal focus will mean very diminished optic quality.
    3. I put my Hyperion into its output barrel. When I start to screw it, the EP skews! Not just a bit, but 2-4 degrees! Owh, oh this is unbelievable... thrown money and how they can sell such GARBAGE??
    Nexstar 8SE + Hyperion Zoom 8-24mm MarkIII + Opticstar
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    Hokie:

    I own and use both a Nexstar 8i (same as the newer model ..8Se) and a CPC1100...

    I run a Denkmeier S1 2" diagonal on both ... BUT in all honestly I seriously doubt that replacing the stock OEM Diagonal will let your eyeballs "see" any difference...you eyes are just not going to be able to take advantage of the slight increase in reflectability ...

    I find Olegvis post interesting as I never saw any false color with either scopes original diagonal ... I do not use a Willimas Optics diagonal but I am not about to say his experience is not normal or unheard of ..

    All of my lower powered eyepieces (25 mm and higher power) continue to be in 1.25 inch format and all of my lower power eyepieces (26 and lower power ) are in 2 inch format mainly to give me a "hair" and I do mean "hair" wider FOV

    I like 2 inch Diagnals..BUT I sure would NOT invest in any diagonal until you have used the scope for no less then 6 months ..and that would be too soon in my opinion...

    a good Solid Observation Chair will serve you 10 times more VISUALLY then the diagonal ...(notice i said visually..because the chair is for your eyes not your tail end or legs or back..).

    What you will most definitely need at first is a dew shield and an external power source like a power tank...Both are necessities.

    Bob G
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    One advantage of 2" diagonals is they screw on to the back of the OTA which is more secure than how 1.25" diagonals are mounted/secure, usually with two thumb screws.
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    Quote Originally Posted by kingmeow View Post
    One advantage of 2" diagonals is they screw on to the back of the OTA which is more secure than how 1.25" diagonals are mounted/secure, usually with two thumb screws.
    Not all 2in diagnoals are screw backs ...Stellarvue does not make a screw back diagnoal but there diagnoals are top notch equipment Look here ... http://www.astronomyforum.net/astron...-dsc08663.html
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    Oh, I was emotional yesterday, sorry! After Friday relaxation..
    About false color - I was very surprised and saddned when I saw it in my SE8. First I thought that my scope is broken (though collimation is very good).
    Then I googled for some 8SE images and many of them have same blue band from one side and red from other, e.g.
    Lunar B / CelestronImages.com - astrophotography with optics from Celestron Telescopes.
    Jupiter with a HD video camera / CelestronImages.com - astrophotography with optics from Celestron Telescopes.
    Jupiter / CelestronImages.com - astrophotography with optics from Celestron Telescopes.
    Why a reflector would have color banding? I suppose this may be from a glass prizm or EP which are slightly tilted. I did not yet have a chance to test my new WO 1.25 diagonal (I hope that it will be better than my first opinion of it!)
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    I didn't follow Bob327's advice and purchased the 2" diagonal a week after I received my 8SE - just couldn't wait to check out some 2" eyepieces. I purchased a GSO 2" 90-deg 99% Dielectric Mirror Diagonal for SCTs - attached to the back of the OTA. I have been happy with it so far - but I don't have anything to compare it to.

    My collection to date:

    Celestron 7AH Power Tank
    Celestron dew shield
    GSO 2" diagonal & GSO 2" 2x ED Barlow Lens
    Celestron 1 1/4" Barlow
    Celestron eyepiece kit filters
    GSO 8x50mm RACI
    Bob's knobs
    Hand Control Mounting Bracket (JMI)
    Eyepieces: Astro Tech Titan Type II ED 40mm, GTO Proxima 31mm, Meade QX 30mm, Meade 5000 SWA 20mm & 24mm, Hyperion 17mm.

    I have not had a chance to try out the Hyperion or Proxima yet - cloudy weather in the north east.

    Based upon my experience and eyepiece collection to date I don't think I'll be using the Barlow much. It is a monster compared to the Celestron 1 1/4" Barlow. I purchased the Celestron eyepiece kit when I purchased the 8SE (came as part of a package deal) and have given most of the eyepieces to my son who has an Orion SkyQuest XT8i Dobsonian telescope - helped him expand his collection. The carrying case has come in hand for storing my eyepieces and I have used a few of the filters - full moon is blinding.

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    Norskeob:

    I have NO problem with your choices I just advise playing with the OEM scope for a couple of months.

    Your choices are fine.... in fact they are more then fine...

    Bob G

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    Default Re: Telescope, 2" diagonal vs 1.25 diagonal on an 8" NexStar SE SCT. Big advantage?

    I bought the Celestron Evo 8" and the star diagonal is poorly collimated, and i dont think that the OEM celestron star diagonal is a good quality piece.

    Do you recomend changing it?

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    Default Re: Telescope, 2" diagonal vs 1.25 diagonal on an 8" NexStar SE SCT. Big advantage?

    Quote Originally Posted by olegvj View Post
    Oosh.. when I got my 1.25 William diagonal.. I greatly stunned with disappointment and sisbelief of this poorly constructed pice of shit.
    Oleg,

    I'm surprised to read this. I have a 2" William Optics diagonal that I use with my short tube refractor. It oozes class. One of the best bits of kit that I own.
    Are you sure that your one hasn't simply been damaged in some way before it got to you?

    Alec.
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