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the shoulder of a ff/fr ?

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4 replies to this topic

#1 Dirtydrywaller

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Posted 22 April 2021 - 06:57 PM

hi

where exactly would the shoulder of a field flattener/focal reducer be located.

 

im trying to get 55mm for the camera.

 

thank you.



#2 ZL4PLM

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Posted 22 April 2021 - 07:15 PM

usually from the start of the threads on the rear - which reducer are you using ?


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#3 Dirtydrywaller

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Posted 25 April 2021 - 12:06 AM

usually from the start of the threads on the rear - which reducer are you using

its a astrotech 0.8 ff/fr

 

https://www.astronom...actor-3516.html



#4 ZL4PLM

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Posted 29 April 2021 - 06:36 PM

its a astrotech 0.8 ff/fr

 

https://www.astronom...actor-3516.html

yup from the start of the threads on the rear 



#5 TAS

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Posted 30 April 2021 - 09:27 AM

 

I have the same focal reducer and had the same question. I contacted Astronomics.

Their reply was that the 55mm is measured from the shoulder of the focal reducer.

 

This my setup with an ASI385.

Note that the gage itself is not 55mm but is the spacing when the sensor is correctly spaced @55mm. 

 

TAS

AstroTech .8FR 55mm spacing
 
AstroTech .8FR Gage And 1.6 extension assy

Edited by TAS, 30 April 2021 - 09:41 AM.



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