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Edge 8hd & asi224

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#1 skat

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Posted 03 August 2020 - 09:31 PM

Hello,

I have an Edge 8hd and recently ordered a zwo asi224mc (does not come with any extensions).  My question has to do with mounting the camera with the proper back focus distance.  The 8hd b/f distance is 133mm.  I have the 8hd t-adapter (78mm).  The asi224 has b/f of 12.5mm.  So 133 - 78 - 12.5 = 42.5mm.  The sequence I think I need is:  telescope - hd t-adapter - m42-48 adaptor- zwo 21mm extension - zwo 21mm extension - ???? - asi224.  This will get me to 132.5mm (counting the 12.5mm of the asi224) but not sure how or if the asi224 will screw into the back of the last 21mm extension.  Do I need another 42-48 adapter between the last 21mm and 224?  Does this chain make sense?  Is there a better way to do this?  Any input will be greatly appreciated.

 

Thank You



#2 Alien Observatory

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Posted 03 August 2020 - 10:03 PM

At F10, as I remember, when I  had an Edge 8",  just a Celestron SCT to T Thread adapter and a 15 to 25 mm T Thread spacer is all that is needed. Do not stress out about the exact measurement as you have a telescope focus available to make it "just a ball park measurement".  The ZWO 21mm T  Thread spacer is exactly what is needed with the Celestron SCT to T Thread adapter...Pat Utah smile.gif

 

https://agenaastro.c...pter-93633a.htm


Edited by Alien Observatory, 03 August 2020 - 10:38 PM.


#3 orionic

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Posted 04 August 2020 - 12:15 AM

I'll admit I know very little about this, but for the Edge HD I think this is the one you're supposed to use

https://www.celestro...dapter-edgehd-8

although perhaps it doesn't matter as long as you add spacers as needed to get the right back focus distance.

 

I have used the 224 with my Edge 8 HD, although never at f/10.  I don't think I have ever used the exact recommended back focus distance due to obstruction with the mount.



#4 GazingOli

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Posted 04 August 2020 - 05:49 AM

You can simply use a set of spacers like this:

 

https://www.bresser....n-Tube-Set.html

 

It comes with SCT 2" thread adapter. Simple as can be - try how much space you need.

 

20200521_001756k.jpg

 

I am using a Click Lock instead with 2" barrel. But it works either way.

 

CS.Oli


Edited by GazingOli, 04 August 2020 - 05:51 AM.


#5 skat

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Posted 04 August 2020 - 10:16 PM

Thank you all for the replies.  Orionic, that's exactly the adapter I have now.  I wasn't sure if the telescope's focus was used since no one ever mentioned it in all the searches I have done trying to find the right answer.  An extension spacer kit is something I will search for.

 

Thanks again for all your suggestions.

Steve



#6 skat

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Posted 10 August 2020 - 02:35 PM

I would like to add that I found a set of spacers rings that helped solve my problem.  Agena Astro has a spacer set ( Blue Fireball PAAR-BF-S-SET1) that are all M42.  Hope this helps.




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