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1ST Light for the C9.25 white light filter.


Pete Presland

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Been wondering what the C9.25 would be like for white light imaging. So i finally "bit the bullet" and bought an A4 sheet of Baader 3.8 Solar film.  Made a half decent filter, and used lots of masking tape for todays test run.

The conditions were not great, but I think the set up has potential for those days of excellent seeing and large Sunspots. 

The preview doesn't look much, but clicking on full resolution will hopefully shows what i mean. 

Baader 3.8 Astro-film, C9.25, Asi290mm, x1.8 Barlow.

1510326962_2022_04_2410.021stlightC9_25.thumb.png.cc74bd5b8e14972b497705fce344416a.png

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Very nice image Pete! 

Ags - Thing I remember from trying WL for the first time with an SCT was how difficult the Sun was to find without a well aligned finder. Worth getting some solar film for your finder if you don’t have a proper solar finder for your C6

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5 hours ago, neil phillips said:

Congrats on getting the C9.25  on the game. A good first light. Nice detail

What size is the filter Pete. ive ordered some 3.8 OD for my newt. but with be stopped down to around 7.5

M

About the same, 190mm aperture.  I might try and squeeze another 10mm maybe.  

The central obstruction is huge on my c9.25, I guess this makes quite a difference as well.

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6 hours ago, Pete Presland said:

About the same, 190mm aperture.  I might try and squeeze another 10mm maybe.  

The central obstruction is huge on my c9.25, I guess this makes quite a difference as well.

Cheers for the info. Yes its losing some to the tape or glue onto the cardboard. what did you do tape  ? how will you squeeze another 10mm out ? 

After trying to get the cell ready today. Ive realized it doesnt have to be taped or glued.  So guessing you meant just widen the hole

Edited by neil phillips
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14 hours ago, neil phillips said:

Cheers for the info. Yes its losing some to the tape or glue onto the cardboard. what did you do tape  ? how will you squeeze another 10mm out ? 

After trying to get the cell ready today. Ive realized it doesnt have to be taped or glued.  So guessing you meant just widen the hole

yes i am going to open the aperture up another 10mm in diameter. Which gives me 5mm still either side at the narrowest dimension (210mm) to fix the film in position. 

I did a few calculations to see the difference between the aperture sizes, in terms of area.  Any errors i am blaming the online calculators!

The Evostar 120mm has an area of 45,238mm

The 200mm aperture filter is 125,663mm, minus the 90mm central obstruction (45,238mm) on the C9.25, gives me an area of 100,217mm. well over a 50% increase. 

 

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