Skywatcher ED 90 + pst mod II

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Cyrille

Skywatcher ED 90 + pst mod II

Post by Cyrille »

Hello,

This my first post :D .
I would like to share the mod II I did by following all the great information you provided into this forum.
Hope that will help other too.

First the Refractor :
Following the great advice of Oliver Smie, I choose a skywatcher accuter 90/900 ED.
It is a great ed refractor that cost less than the ed 80....300€
The link :
http://www.astroversand.com/Skywatcher1 ... O-ED-9.htm
I bought this refractor and ship it to Oliver. He adapted it for a prominence viewer and for H-Alpha :

So this tube is used for :
- prominence viewer (done by Oliver)
- h-Alpha, with pst mod
- Deep-sky & planets.
In all mode, I am using this refractor for visual only with a binoviewer.
DSO and planet views are excellent. Chromatic aberrations are better corrected than with a 80ED.

About the configuration for the Sun H-alpha views :
- a Belpotik ERF
Image
- a skywatcher 1:10 focuser to replace the default one (not mandatory)
- a x1.8 Siebert optic corrector for the binoviewer head. It is a dobson corrector for bino.
Its performance are excellent. This corrector gives great result with the pst and the default 5mm blocking filter.
Image
That means that with this corrector it is not required to put the 5mm filter at each eyepiece.

The tube has been cut so I can use the refractor focuser with the bino head + the x1.8 corrector and with the etalon around 700mm (700 = 900mm-200mm) +/- 4mm.

About the pst mod II:
1.25 eyepiece holder + 2'' 14mm extension + 2'' to Sct adaptor + 1'' sct extension + Etalon + 2'' pst nose
Image
I used some teflon tape to fix the 1'' sct extension to the etalon.

About the diagonal :
I modified a celestron 1.25 diagonal, put the 5mm pst filter as eyepiece holder and place a KG5+a mini ref at the nose of the diagonal. With the siebert corrector I can get view into the bino without vignetting.
But at this focal (900) eye positioning is more critical.
So most of the time, I am using a BF15 I own and let the 5mm diagonal for a 60mm solarmax. Witht he BF15, views are brighter and my eye positioning is simpler.

About the eyepieces :
On the pst alone : 30mm ploss = full view of the sun with h-Alpha on 90% of the disk.
With the 90 ED : I am using a pair of Radian 18mm. The result a tremendous :full h-alpha into the fov. With 30mm Ploss, views are great but only a parts of the view is full of h-alpha details.

About the results :
I do not do photo. I can only share my feelings.
Day to day usage :
I have to wait 20mn before getting the best views. This time is required to get the same temperature across all the elements. This setup remembers me my old TScanner and I am very happy with it.
Comparaison with a Daystar.
I own a 0.5 TScanner that has been transformed with the new ION housing. It has 30mm clear aperture.
I am using a MARKV bino head with it.
Image
I found that the result with the pst mod II provides more contrast and pleasant view than with the daystar without the requirement to put my head under a carpet to make the black around.
But the clearer the sky is, the longer my eyes adaptation is and greater and subtil the details with the daystar are.

Final result :
Image
If you already own a pst, considering the price, this mod cost less than 1000€ to get a 90mm H-alpha refractor.
My own opinion : it is a bargain and nothing can compete because at the same time you will get a marvelous lightweight travel telescope for night and days.

Thanks for all your helps and great previous post !
Greetings,
Cyrille


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Re: Skywatcher ED 90 + pst mod II

Post by Merlin66 »

Good to hear from a happy PST mod user.
Neat set up.


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Re: Skywatcher ED 90 + pst mod II

Post by marktownley »

A great setup and a great write up! Thanks!


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Re: Skywatcher ED 90 + pst mod II

Post by Carbon60 »

Looking good there, Cyrille. Nice set-up.

Welcome to this wonderful site.

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
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Cyrille

Re: Skywatcher ED 90 + pst mod II

Post by Cyrille »

Thanks for yours welcomes !

Cyrille


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Re: Skywatcher ED 90 + pst mod II

Post by MapleRidge »

You have a great set of equipment there, and a nice write-up about the systems too.

Brian


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Re: Skywatcher ED 90 + pst mod II

Post by swisswalter »

Hi Cyrille

thank you for sharing and welcome to that wonderful site. Have sun and fun


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
Cyrille

Re: Skywatcher ED 90 + pst mod II

Post by Cyrille »

Hi,

To try to give a small idea of the FOV with bino head+18mm+x1.8 corrector and result of the mod
I made a single shot of the sun last friday with my canon 600 + x5 power mate.
It was a quick&dirty setup :
- I used the DM4 mount of the previous picture (az mount, no tracking),
- Coarse focus because the mount was not tracking,
- No flat/dark/ etc...,
- The etalon was at 70mm too far from its best position,
- Histogram adjustment + resize.
Image

Cyrille


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Re: Skywatcher ED 90 + pst mod II

Post by marktownley »

Not a bad start!


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Re: Skywatcher ED 90 + pst mod II

Post by swisswalter »

Hi Cyrille

that looks promising


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: Skywatcher ED 90 + pst mod II

Post by Merlin66 »

Cyrille,
When you achieve the optimum spacing of the etalon to the prime focus -200mm Majic happens!!!!
The Crayford should not be used, but "locked into final position" - you will need an additional focuser between the etalon and the eyepiece/ CCD.


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
Cyrille

Re: Skywatcher ED 90 + pst mod II

Post by Cyrille »

Thanks for your encouragement !
Now I have to read again all yours previous post :D

Cyrille


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