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Finding Scopes That Are Well Corrected For Ca-K Imaging

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David_The_Bears_Fan
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Finding Scopes That Are Well Corrected For Ca-K Imaging

Post by David_The_Bears_Fan » Sat Feb 23, 2019 9:57 am

Simple question, when looking at potential new scopes is there a way to tell if it will be sufficiently well corrected for Ca-K imaging? My assumption is the only reliable way to tell is to try it, which is kind of limiting. Thinking of moving from my achro Skywatcher Evostar to something like an F/10ish ED but whatever I buy must work for Ca-K imaging.
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Kit: Skywatcher Evostar 120 on Celestron CG-4 / Coronado PST / Lunt B1200 Ca-K Module / Lacerta Herschel Wedge/ Canon 1100D & 77D / ZWO ASI178MM & 120MC-S / QHY5-II Mono

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Re: Finding Scopes That Are Well Corrected For Ca-K Imaging

Post by marktownley » Sat Feb 23, 2019 1:27 pm

I think you will struggle to improve on what you have without spending big bucks...
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Re: Finding Scopes That Are Well Corrected For Ca-K Imaging

Post by christian viladrich » Sat Feb 23, 2019 8:05 pm

Maybe a 150 mm F/8 (or 10) Newtonian telescope with a sub-aperture ERF in front of the secondary mirror is the way to go.
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Re: Finding Scopes That Are Well Corrected For Ca-K Imaging

Post by bart1805 » Sat Feb 23, 2019 8:56 pm

Hi David,
Here is an interesting thread about this question:
viewtopic.php?f=10&t=25115&hilit=small+scopes+cak
If money is no problem I would go for a TOA 130 or 150. A nice entry, often offered secondhand, is a Synta 100mm ED f/9.
CS! Bart.

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Re: Finding Scopes That Are Well Corrected For Ca-K Imaging

Post by David_The_Bears_Fan » Sat Feb 23, 2019 11:02 pm

Thanks Guys
@Mark - Had crossed my mind. I was actually considering the upgrade to try and up the quality of my white light images (removing some of the losses caused by chromatic aberration) but do not want to adversely impact my Calcium imaging.
@Bart - great thread with some interesting links, thanks.
David

Kit: Skywatcher Evostar 120 on Celestron CG-4 / Coronado PST / Lunt B1200 Ca-K Module / Lacerta Herschel Wedge/ Canon 1100D & 77D / ZWO ASI178MM & 120MC-S / QHY5-II Mono

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Re: Finding Scopes That Are Well Corrected For Ca-K Imaging

Post by marktownley » Sun Feb 24, 2019 5:00 am

The other way to look at this is to improve the overall quality of the data you are are recording; you could get a SSM http://astrograph.net/epages/www_astrog ... ccessories

Does the 178 camera support binning? The native pixel size is small and suited to short focal ratios, binning would increase the fps and sensitivity, reducing exposure time.

Going above the 120mm aperture you have already, the seeing is always going to be the biggest factor.

Are you using a continuum and UV filter with your whitelights?
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