EdgeHD 9.25 first light

[kosborn (Kevin)]

Hi all,

I haven't been doing a great deal of astrophotography lately, and haven't been visiting here much at all. I thought I'd post this one though. I've been craving focal length for a little while, and in my dreams, explored the Planewave CDK 12.5 and Sidereal Trading's version of the CFF Ritchey–Chrétien (isn't that a work of art!). Both are expensive (particularly the Planewave), and the thought of collimating the RC really scares me! So instead, I got hold of a Celestron EdgeHD 9.25. I had decided I'd never own a Schmidt-Cassegrain, but it's easy to collimate and cheaper than the other options and seemed like the best solution. First light at native focal length (2350mm) is NGC 300 with an ASI 2600mm and Antlia filters. The stars are a bit bloated, mostly due to poor tracking I think, and back focus needs to be tweaked a bit, but overall, I'm happy with it. To see the funky stars at the edges and equipment and exposures details, more is on Astrobin.

[CaptainCook (Gary)]

That looks really nice...where's the astrobin link please?

[kosborn (Kevin)]

Originally Posted by CaptainCook

That looks really nice...where's the astrobin link please?

Thanks! Apologies, Astrobin link is https://www.astrobin.com/053sie/

[Startrek (Martin)]

Hi Kevin,
Yes it’s been a while
A great result for your first light
Well done 👍
I assume you’re running Gain 0 on the 2600MM for broadband ?

Cheers
Martin

[kosborn (Kevin)]

Originally Posted by Startrek

Hi Kevin,
Yes it’s been a while
A great result for your first light
Well done 👍
I assume you’re running Gain 0 on the 2600MM for broadband ?

Cheers
Martin

Thanks Martin. I'm actually running at gain 100 with 120s exposures for lum and 180s exposures for rgb as the scope at native focal length is f/10 (compared to f/5 for my Newtonian). Would you suggest reducing the gain?

Kevin

[Dave882 (David)]

This is fantastic Kevin. Lovely resolution in those spiral arms. I love long fl imaging (and viewing!!) - it's so rewarding once you sort out the gremlins. Some funky star shapes/chromaticism at the edges is pretty common for dso imaging with scts and can be reduced with careful tweeking of backspacing and collimation - but very hard to eliminate entirely (wouldn't we all love to have the finances for a cdk lol)

[Startrek (Martin)]

Originally Posted by kosborn

Thanks Martin. I'm actually running at gain 100 with 120s exposures for lum and 180s exposures for rgb as the scope at native focal length is f/10 (compared to f/5 for my Newtonian). Would you suggest reducing the gain?

Kevin

Hi Kevin,
Gain 0 does give you a deeper well and more DR , it might help your fine detail and control the larger stars ??
Give it a try ?
I’ve always gone Gain 0 for Broadband and Gain 100 HCG for Narrowband with both 2600MC and 2600MM in Sydney B7/8 and South Coast B3.
I just followed a heap of folk on CN when I bought my cameras and they had good results at focal lengths , f5 to f10

Martin

[strongmanmike (Michael)]

Ah, missed commenting on this one Kevin, I really like the colour balance on this, nice job. Yeah, the stars are maaaybe a little SCT'ish but not that bad, really only noticeable at full res, overall a pleasing image, you must be quite happy

Mike