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Wide Angle Astrophotography

Beginner Astrophotography Equipment Refractor
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#1 ryan_pablo

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Posted 20 October 2021 - 10:04 AM

Hi all. Newbie here and I looking to building my first deep sky set up. I want to start out with a wide angle refractor telescope (preferably a triplet refractor). My goals are to capture the California Nebula, Heart and Soul Nebula, Andromeda Galaxy, Veil Nebula, and more. I am leaning towards the Radian Raptor 61 or the William Optic 71GT. I like how they both come with a flattener and are around the same price. I am favoring the 71GT but I am curious if that might be too much of a focal length to capture my desired objects. Any suggestions? Thank you.



#2 Simcal

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Posted 20 October 2021 - 10:14 AM

Hi Ryan, play around with this imaging calculator here:  https://astronomy.to.../field_of_view/

 

You can enter telescope or pick from a list, enter imaging camera, and the target object and it will frame it up for you. waytogo.gif


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#3 ryan_pablo

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Posted 20 October 2021 - 10:23 AM

Hi Ryan, play around with this imaging calculator here:  https://astronomy.to.../field_of_view/

 

You can enter telescope or pick from a list, enter imaging camera, and the target object and it will frame it up for you. waytogo.gif

Thank you! I'll play around on this site to weigh my options. 



#4 SilverLitz

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Posted 20 October 2021 - 03:18 PM

It is the combo of camera (sensor size & pixel size) and scope (FL & quality image circle size).  Think FoV and image scale of the combo.  Most of the scopes do not do full-frame well, even if they quote 44mm image circles, as the stars get wanky or the vignetting gets noticeable.  I have recently found that vignetting that normally corrects well can give calibration problems with moon wash conditions. 

 

If you want to go full-frame camera size ($$$$), you will need the the high $$$$ scopes (A-P, Tak FSQ, Tak TOA, TEC, CFF, higher end SV SVX, TV) to cover the sensor well.  For most scopes it seems that APS-C is the good wide FoV sweet spot, with ZWO 2600 or QHY268 being the pick of the litter.

 

For very large targets (Cygnus Loop, Question Mark, Heart+Soul), my combo is a QHY268M with a Vixen FL55ss reduced to 237mm.  Previously, I used a Samyang 135mm f/2 lens with a 183mm, but the FL55ss/268 is much better.  For large targets, such as M31, I use an Esprit 100 reduced to 413mm with the QHY268.  M31 could also fit with a 300mm FL lens with the 183 camera.

 

The alternatives to the Vixen FL55ss would be WO RedCat 51 at 250mm FL or the Radian Raptor 61/Sharpstar 61 EDPH (basically the same) with their reducer at 275mm FL.  Either of these are lower priced than the FL55ss.  If you go the Raptor 61/Sharpstar 61 route, be aware that they have CA issues with their FR/FF.  The Vixen FL55ss has advantages of using fluorite and the flexibility of 2 flat FLs: 237mm at f/4.3 or 312mm at f/5.7, with its FF+FR package.  However, the Vixen FL55ss is less convenient when it comes to integrating into an M48 image train, requiring an extra adapter.



#5 pyrasanth

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Posted 20 October 2021 - 04:19 PM

The RASA options are also very good with medium sensor cameras and above. The RASA 11" requires quite a decent mount but is more forgiving with backfocus and camera choice.


Edited by pyrasanth, 20 October 2021 - 04:20 PM.



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