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New scope test: 2-pane NorthAmerican/Pelican mosaic

astrophotography CMOS dso refractor
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#1 OldManSky

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Posted 15 July 2020 - 10:34 PM

I admit it - I have a tiny imaging chip (ZWO ASI183mm-pro).  But I crave wide-field nebula shots, especially in the summer.

To get as wide a field as possible, I picked up a new imaging refractor last week -- the Sharpstar 61EDPH-II.  The Sharpstar 61 has been out for a while as a doublet, just recently they upgraded to the "II" model, making it triplet refractor.  With the designed-for-it 0.8x reducer/flattener, it becomes a 275mm FL f/4.5 wide-field triplet APO.

 

I got it all assembled and mounted on top of my GT71 refractor, which is now acting as guide scope.  Had two mostly clear nights Monday and Tuesday, so I gave the new refractor a test with a 2-pane mosaic in Cygnus.  Monday night I did the Pelican Nebula side, 2 hours of Ha and 1 hour each of G and B.  Tuesday night the same time but on the North  American nebula side.  Got them all calibrated and registered and assembled today.

I'm pretty happy with the new little super-wide-field refractor!  I used the standard 55mm backfocus distance from the flattener/reducer, not accounting for my filters, and it's clear it needs just a bit more distance back to get a totally flat field, but it's close.  And I'm pretty happy with the 2-night 8-hour test shot below.  Looking forward to the rest of summer/fall and lots of wide fields!

 

Thanks for looking, comments & criticisms appreciated.

 

Attached Thumbnails

  • 61edphii_firstlight_2pane_small.jpg

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#2 sunnyday

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Posted 15 July 2020 - 10:36 PM

the depth of this photo is incredible, very nice details, bravo and thank you.


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#3 yzhzhang

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Posted 16 July 2020 - 02:06 AM

Turns out pretty good, Congrats!

 

It does appear to me a bit of purple stars and seems more on the pelican side. Is that focusing on that night, or the CA under-correction?


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#4 imtl

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Posted 16 July 2020 - 02:24 AM

It might be more to the fact that he is doing HaGB and not HaRGB.



#5 OldManSky

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Posted 16 July 2020 - 03:41 AM

Turns out pretty good, Congrats!

 

It does appear to me a bit of purple stars and seems more on the pelican side. Is that focusing on that night, or the CA under-correction?

Focusing on that night.  I began earlier that first night (when the target was just about 30 deg. altitude) than the second night.  




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