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Field flattener for 120mm f/8.3

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#1 joelin

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Posted 14 October 2019 - 12:47 PM

Is there such a thing as a field flattener for 120mm f/8.3

 

Its an achromat so not ideal for imaging, but maybe if I can use a field flattener and a minus violet filter that would help. 



#2 sg6

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Posted 14 October 2019 - 01:08 PM

May find a flattener, they were specified by f number, not focal length for some reason.

As to the minus violet that means it blocks some red and some blue, so result is yellowish.

Likely not worth it for imaging, cameras tend to see the colors more.

 

Really is a case of just accept the situation, tweek the focus to get the best you can.

Has the scope got a 2 speed focuser?

 

Rotten side is you need an ED or an apo.




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