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Takahashi e-180 + ASI6200 Back focus?

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#1 drice

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Posted 31 October 2024 - 12:33 PM

Hello, I am trying to connect my ASI6200 and EFW to my Takahashi E-180.  Details are hard to find. Many ZWO products seem to be lacking in documentation. Takahashi says the scope has 56mm back focus. The ZWO 6200 cameras says 55mm. Not sure if one replaces the other or use the difference? 

 

Main issue is it would seem that you would connect the ASI6200 + EFWheel + spacer rings + E-180 scope @ the corrector lens which is 54mm female. The spacer rings end as female as well. Male to male adapter needed? 

 

Anyone got this figured out? Thanks.  -Derryl

 

 

Attached Thumbnails

  • 6200-55mm-backfocus-solution-2-2.jpg


#2 orion899

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Posted 31 October 2024 - 02:09 PM

Hello Darryl,
just set this up last week after getting 54mm filter drawer
from Agena Astro. Backspace is 56.2 mm I had a thin .2 spacer around that came
with one of the Zwo cameras, only problem is it’s 42mm so I had to cut it to try
and make it work. Your camera has the same 17.5 mm as my 2600 and the filter
drawer is the same 20mm as your EFW

Here’s the diagram

Attached Thumbnails

  • IMG_2024-10-31-145759.jpeg
  • IMG_2024-10-31-145349.jpeg

Edited by orion899, 31 October 2024 - 02:10 PM.


#3 joshman

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Posted 31 October 2024 - 04:02 PM

The Backfocus requirement is a property of the optics, in this case the E-180.

 

55mm is a common backfocus design, so ZWO demonstrate how to achieve with their system.



#4 drice

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Posted 31 October 2024 - 04:20 PM

Hello orion899, thanks for the chart and info.  It's not quite clear on the connection to the Tak, did you have to use a male-to-male adapter? Also, shouldn't the filter drawer be directly next to the camera? Thanks.  -Derryl



#5 drmark67

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Posted 31 October 2024 - 04:24 PM

Hi Darryl 

My e180 manual specifies 56 mm exactly and that is what I have found to be best. I have experimented with .1 mm changes and there is noticeable coma at 56.2 mm, your specific e180 may be different, and yes, the e180 is extremely sensitive to back focus changes.

Additionally, you will likely need a male to male adaptor in your imaging train.

Hope this helps.


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#6 orion899

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Posted 31 October 2024 - 07:15 PM

[quote name="drice" post="13772643" timestamp="1730409637

Hello orion899, thanks for the chart and info.  It's not quite clear on the connection to the Tak, did you have to use a male-to-male adapter? Also, shouldn't the filter drawer be directly next to the camera? Thanks.  -Derryl
[/quote]
Ya got me Derryl,
When I put that together I just got an order from Agena and was trying
to get the proper backspaces on the
Epsilon and a fsq85. 42, 48, 54, and 56 mm sizes.
Anyway here’s a few more pics. Being this is what I had went from 54 male scope
end 16.5 length to drawer 54 male scope end to a 54 to 48 male to male which with the 17.5 camera gives the 56 mm backspace.
In my research there is multiple references to 56.2 for backspace. Before I got the 54mm drawer that seemed to work but I’m
not that experienced.
O yeah I reversed the filter drawer.
Mike

Attached Thumbnails

  • IMG_2024-10-31-195606.jpeg
  • IMG_2024-10-31-195636.jpeg

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