Thread: Calculating/maintaining back focus
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Old 22-09-2017, 12:28 PM
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Atmos (Colin)
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Join Date: Aug 2011
Location: Melbourne
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Adding filters ADDS to the optical back focus but SUBTRACTS from the mechanical.

A flattener that has a 55mm back focus, when adding a 1mm filter you calculate it from a 55.33mm optical back focus.
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