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Celestron Celestron 1.25" Telescope Prism Star Diagonal # 94115-A

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#1 Stopforths

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Posted 25 July 2021 - 02:30 PM

Does anyone know if this prism is coated or not.  Doesn't say this in specs online???


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#2 Sky Muse

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Posted 25 July 2021 - 03:09 PM

Does anyone know if this prism is coated or not.  Doesn't say this in specs online???

Yes, it is...

 

Celestron 94115-Ab.jpg

 

I then coated my own with jet-black, matte paint, onto carefully selected areas, to improve contrast.


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#3 Stopforths

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Posted 25 July 2021 - 03:48 PM

Thanks for that appreciate it.   Just ordered one.  I'll definitely be blacking it out like you have.  Just prefer prisms to mirrors for binoviewers and planetary detail by a whisker and recall the one I used to have was a good performer..

 

 

 

Phil B


Edited by Stopforths, 25 July 2021 - 05:40 PM.

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#4 Stopforths

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Posted 28 July 2021 - 02:58 AM

It arrived lovely coatings fit and finish ok too.  last owned one decades back and this looks to be better coated etc.


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#5 Phil Barker

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Posted 28 July 2021 - 01:33 PM

Well Well Well or 3 holes in the ground as my friend used to say.

 

The Celestron prism was given a light test last night and here's what I found versus a dielectric gso.

 

At times I didn't know which one I was using most of the time it was dark and I didn't have my glasses on.  This will be familar to some of you over lol.gif

 

Both perfromed well on jupiter and the moon.  On jupiter I really noticed when the volume was up ie 216 times one showed a light haze and it was light and one clearly didn't.  The prism was frankly completly free of this and the mirror had it.   I have 2 versions of the gso dielectric another with a .965 insert and it was the same as its sibling.

 

The colours looked a tiny bit better ie easier to make out some colours in the Celestron prism .

 

Brightness couldn't tell.  Both handled high power well I was using a mewlon 180C a fine scope.

 

The moon was amazing in both couldn't pick a difference there although a hint of a better balanced colour in the prism.  No CA on the limb in either I could make out.

 

I then tried the trusty Celestron binoviewer with 2 17mm televue plossls and a 1.7 extender lens.

 

Some very slight CA on the limb showedwhen  prism used and less when mirror diagonal used.  

 

Nice views.   No night and day difference.

 

The celestron seems a nice piece of equipment for the price.  Lovely coatings doesn't loose any light it seems and the views are fine at higher ie over 200 x.

 

The clouds and early start stopped me from doing more but I'm happy with the very reasonable priced Celestron prism and wondering why more of us don't just use one and switch to a mirror diagonal??? 


Edited by Phil Barker, 28 July 2021 - 06:56 PM.

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#6 Sky Muse

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Posted 28 July 2021 - 04:13 PM

Thanks for that appreciate it.   Just ordered one.  I'll definitely be blacking it out like you have.  Just prefer prisms to mirrors for binoviewers and planetary detail by a whisker and recall the one I used to have was a good performer..

 

 

 

Phil B

You can see what I did to mine here...

 

https://www.cloudyni...kened-flocked/ 



#7 SteveG

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Posted 28 July 2021 - 07:11 PM

I’ve had the same experience with my Celestron prism. It now lives in the focuser of my ED100.


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#8 Stopforths

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Posted 29 July 2021 - 02:23 PM

Had 2 sessions last night with the prism in my fc100.  Its an older version so no binoviewing possible but using it directly couldn't see any issue with brightness sharpness CA they both performed well on venus and several other targets.  The correction is superb in the old florite f8 no CA on Venus in focus amazing!!

 

I spent some time on Omega Centaurus with both prisms and a william optics 16mm and 7mm UWAN

 

They are fantastic eyepieces I could not see any improvement in either diagonal and certainly one didn't seem brighter.  I've done this before with a standard diagonal and the dielectric and the dielectric GSO was brighter and noticeable so using a skywatcher Mak.  Later on  Saturn  using a hi Or at 200 x (4mm) I was getting superb views using both diagonals  still think colour a little bit better in the prism.   

 

Its a good product easy to clean works ok one issue I think may occur is the screws for holding the eyepieces are threaded into plastic so bight have to retap that later on I do a lot of observing.


Edited by Stopforths, 29 July 2021 - 02:24 PM.



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