Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

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astroshot
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Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

Post by astroshot »

As some of you are aware, I have both a Coronado SM90 filter and a Daystar 0.6A T-Scanner. Today, following a suggestion by Mark, I decided to try combine both filters. Below is a short report:

Coronado SM90
First, to describe my thoughts on this filter, I use it with a BF15. I really like this filter as it gives a nice even level of illumination across the disc. Aside from using it with my TEC140 refractor in my observatory, I also enjoy using it with my Skywatcher 102mm f/5 refractor. The SM90 simply threads directly on to the front of the scope - no additional adapter required. I'm surprised Skywatcher do not advertise this (accidental?) feature of their scope. I bought the scope s/h for less than the cost of an adapter! ;-) Makes for a great grab-n-go setup. After shortening the OTA a little, I always use the scope with my WO binoviewers, 20mm eyepieces and 1.6x optical nosepiece. Makes for really comfortable viewing with a nice bright image.

Daystar 0.6A T-Scanner
I use this filter exclusively on my TEC140 due to the optical configuration required. At the front of the scope I use a Baader 135mm D-ERF which sits in a cell over the dew shield, resulting in an effective aperture of 125mm. In the focuser, I have the following:
extension tube / etalon / 4x powermate / diagonal / eyepiece or camera. For purposes of today's test, I used a Televue 2" 56mm Plossl to give a low magnification due to the 4m focal length.
It makes for a long complex setup at the rear of the scope. However, it gives a nice reasonably bright image and a noticeable improvement in resolution over the SM90 due to the increase in aperture.

Coronado - Daystar Combo
SO, with the SM90 on the front, I attached the Daystar and associated equipment on the back of the TEC140 - didn't use the BF15. Immediately, I noticed two things:
1. Noticeable improvement in image contrast and much narrower bandwidth on the central portion of the image. The filament which is currently lying across the centre of the SUn's disc was noticeably darker. Panning across the disc, other filaments came into view that I hadn't noticed with either filter on their own. So, as a double-stack arrangement, it certainly worked.
2. Notice how I said "central portion" above - it's like the inner say 40% has that level of detail. The remainder was noticeably brighter and not as contrasty.
I tried to put my DMK41 on it, but the central portion was so dim due to both filters in action that it needed a long exposure (say 1/8th sec) to get a reasonably bright image on my screen. In fairness, it was also a bit hazy, but that doesn't fuilly account for the dim image. Perhaps a combo best used visually.

After that, I tried to use the Daystar with the SM90 but without the use of the powermate.
In this case, the filament on the disc could be seen. However, it wasn't as detailed or as contrasty as the view with the SM90 and BF15. So, no advantage in using the Daystar in that configuration.


Michael in Kildare, Ireland.
TEC140
Coronado Solarmax 90
Daystar 0.6A T-Scanner
Baader Cool-Ceramic Safety Herschel Wedge
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Re: Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

Post by swisswalter »

Hi Michael

thank you very much for your detailed report.

So the conclusion is, you robbed me an option. As soon as it gets to doublestacking and hires, I'm always out of light. 1/8 of a second is a nogo


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Re: Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

Post by astroshot »



So the conclusion is, you robbed me an option. As soon as it gets to doublestacking and hires, I'm always out of light. 1/8 of a second is a nogo

Correct. Non runner, at least with this combo anyway.


Michael in Kildare, Ireland.
TEC140
Coronado Solarmax 90
Daystar 0.6A T-Scanner
Baader Cool-Ceramic Safety Herschel Wedge
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Re: Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

Post by marktownley »

Oh well, worth a try. Useful to know Michael :)


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Re: Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

Post by astroshot »

I tried observing with both filters again recently.
Starting to like it. Noticeably narrower bandpass.
Detail pops into view that otherwise may not be apparent with a single filter.


Michael in Kildare, Ireland.
TEC140
Coronado Solarmax 90
Daystar 0.6A T-Scanner
Baader Cool-Ceramic Safety Herschel Wedge
Pedro

Re: Thoughts on Coronado SM90 and Daystar 0.65A T-Scanner

Post by Pedro »

Nice report Michael,

The SM90 also threads directly on to the front a TV101 (old and new models).


I will keep it for future reference. Thanks

Pedro


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