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C9.25 or C9.25 Edge HD

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#1 dcm_guitar

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Posted 17 May 2021 - 02:12 PM

I'm trying to figure out a galaxy OTA solution.....

 

As we all know, NOTHING is available.  However, I can get a hold of a C9.25 XLT.  It is not the Edge version.  My understanding is that the non-Edge has no mirror lock, no cooling vents and, of course, does not have the correction out to the edge of the image.  I'd prefer the Edge, but they just are not available.

 

Will I have satisfactory imaging performance (APS-C OSC camera and full frame mono with filter wheel) with the non-Edge and a corrector?  Is finding the correct back focus going to be tricky?

 

Would you get the C9.25 now or wait until the C9.25 Edge HD comes available at some unknown future date?



#2 kraegar

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Posted 17 May 2021 - 02:18 PM

Personally I'd get in an order with someplace and wait it out for the Edge.  Here's an image I took with my C8 XLT + the f6.3 reducer/corrector:

 

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I was guiding with an OAG, and my guiding was tight.  The stars are all egg shaped and point to the middle.  I think if it'd been on an edge HD that would have been a much nicer image.

 

Edit: If the edge scopes were available now I'd have yolo'd one this spring, too.


Edited by kraegar, 17 May 2021 - 02:19 PM.


#3 KTAZ

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Posted 17 May 2021 - 02:19 PM

If you are an advanced imager, I'd wait for the HD.

 

I own the XLT and am happy with my images; however the reducer does not flatten the field nearly as much as the HD version. As a result I am always cropping with my APS-C. As I progress in my capabilities, I foresee moving to the HD once they become available again and prices stabilize.

 

Furthermore, with the XLT you pretty much have to use the reducer to get reasonable stars. At full FL, the stars in the OAG guide scope are truly "seagulls" and contribute to less than optimal tracking. Multistar guiding is very difficult with those types of stars. I don't even attempt full FL at this point.



#4 rgsalinger

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Posted 17 May 2021 - 02:32 PM

If the XLT is used, buy it and then sell it when you can get an Edge. If not then wait it out. There are too many targets that need the full FOV of a long focal length scope.

Rgrds-Ross


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#5 John O'Grady

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Posted 17 May 2021 - 03:21 PM

If the XLT is used, buy it and then sell it when you can get an Edge. If not then wait it out. There are too many targets that need the full FOV of a long focal length scope.

Rgrds-Ross

Wise advice here. I really liked the C9.25XLT that I used to own.  

 

 

Will I have satisfactory imaging performance (APS-C OSC camera and full frame mono with filter wheel) with the non-Edge and a corrector?

I have owned both and in my opinion, the standard XLT version performs well for imaging up to APS-C sized sensors.  There's a bit of fiddling needed with back focus to zero it in for the XLT with the 0.63x reducer.

 

The EDGE works extremely well with both APS-C & full frame.  The celestron standard camera T-adapter does an excellent job dialing in back focus BUT make sure you get the model with 48mm threads to reduce vignetting.    It works with any camera that's already set to a 55mm backfocus.  Both ZWO & (now) QHY have adapters available for their cameras which greatly simplify configuring the camera to a 55mm backfocus.

 

I've found for both my QHY128C and QHY268M cameras, installing supplied adapters (one being a blade series camera adapter from Cyclop optics) for 55mm backfocus hits the sweat spot for the EDGE 0.7x focal reducer.  I have not imaged with the C9 EDGE at f/10 and likely never will given the pixel scale I'm already sampling at. 

 

What's even better, is that I now have three OTA's configured for 55mm backfocus and two cameras with a backfocus of 55m.  So I can move either camera to anyone OTA and the field will be flat.  bounce.gif

 

Hope this is helpful.

 

John



#6 dcm_guitar

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Posted 17 May 2021 - 03:36 PM

All. THANKS!!!!  This was quite helpful.  Greatly appreciated!




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