Thread: My first Horsehead
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  #13  
Old 21-11-2021, 08:52 PM
Startrek (Martin)
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Startrek is offline 		 
Join Date: Dec 2017
Location: Sydney and South Coast NSW
Posts: 6,065
Tony,
Further to Raymo’s comments, have a read of Craig Starks ( Stark Labs ) write up on Aperture, Focal Ratio etc...

http://www.stark-labs.com/help/blog/...ioAperture.php

A great read

Cheers
Martin
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