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Coma corrector questions

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#1 xanadu30

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Posted 02 March 2021 - 12:17 AM

Hello all, I recently purchased an Orion 6" Newtonian Astrograph, and see that in order to take descent images I am in need of a coma corrector.  I understand how and why coma correctors work, but am confused as to how / where I add this piece of equipment to my imaging train.  Currently I have a DSLR with a T ring and 1.25" adapter going into a 2" to 1.25" adapter into my 2" focuser.  In order to incorporate a coma corrector, where does this fit into my imaging train?   



#2 ngc7319_20

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Posted 02 March 2021 - 01:30 AM

Presumably you will have a 2" coma corrector...  So it is Orion 6" > coma corrector > T-ring > camera ---- assuming the coma corrector will accept a "T" connection.

 

The       coma corrector > T-ring > camera       assembly gets dropped into the focuser.

 

Many coma correctors include a T-connection.  Here in photo the Astro-Tech coma corrector includes a 48mm to T adapter pictured at the lower right.  In this case the chain is something like:

 

coma corrector lens > 48mm to T adapter > T-ring > camera

 

AT coma.jpg .


Edited by ngc7319_20, 02 March 2021 - 01:36 AM.


#3 Phil Sherman

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Posted 02 March 2021 - 12:03 PM

Coma correctors are designed to have a specific distance between the corrector and your imaging chip. This distance is almost always 55mm. The T adapter for your camera will position the imaging chip 55mm from the front flange of the adapter. This should mate perfectly with the coma corrector.


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#4 xanadu30

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Posted 02 March 2021 - 03:01 PM

Presumably you will have a 2" coma corrector...  So it is Orion 6" > coma corrector > T-ring > camera ---- assuming the coma corrector will accept a "T" connection.

 

The       coma corrector > T-ring > camera       assembly gets dropped into the focuser.

 

Many coma correctors include a T-connection.  Here in photo the Astro-Tech coma corrector includes a 48mm to T adapter pictured at the lower right.  In this case the chain is something like:

 

coma corrector lens > 48mm to T adapter > T-ring > camera

 

attachicon.gifAT coma.jpg.

Thanks.  So, the large piece of the three shown above is not used?  Is this for eyepiece use?



#5 ngc7319_20

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Posted 03 March 2021 - 03:42 AM

Thanks.  So, the large piece of the three shown above is not used?  Is this for eyepiece use?

Correct --  the large piece that says "Astro Tech" with thumbscrews is not used for imaging.  It is only to hold 2" eyepieces in visual mode.




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