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Orion Field Flattener for Short Refractors 400-650mm

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#1 joelin

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Posted 21 October 2019 - 12:58 AM

When using this, does the back focus ever vary from the recommended 55mm based on the focal length or ratio of the refractor?

 

if I want to use it for a shorter focal length of 360mm, can I still get good results by varying the back focus length to be higher or lower.?



#2 Migwan

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Posted 21 October 2019 - 07:41 AM

FF are geared toward specific fl, so I wouldn't.    This one probably more what you are looking for.  Link   You'll have to check it out for size and fit.   Good luck.

 

jd



#3 joelin

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Posted 21 October 2019 - 11:56 AM

It seems like they work for a range

The one I purchased says 400-660mm

#4 RandallK

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Posted 21 October 2019 - 12:02 PM

I believe the 55mm backfocus remains the same (I have one for my 80mm apo refractor).




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