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Archive 2009 · F-stop theory question

  
 
amacks
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p.1 #1 · F-stop theory question


I think I understand the basic reason why marked F stops start to become meaningless at macro distances, but I have a related question. Does the skew, that is the amount larger the actual f-stop number is from the marked number, increase or decrease with longer focal lenghts?
That is, if I have a 60mm f2.8 and a 100mmf2.8, both focused to make an object appear 1:1, which will be more skewed from the marked f-stop?
a



Nov 03, 2009 at 12:53 PM
LordV
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p.1 #2 · F-stop theory question


AFAIK the Fstop "skew" is mainly linked to magnification not focal length.
Apparent F= F * (1+M) where M is the magnification.

Brian v.



Nov 03, 2009 at 01:05 PM
amacks
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p.1 #3 · F-stop theory question


How is magnification described for that formula? is it the usual macro 1:1 as a fraction or
A



Nov 03, 2009 at 01:19 PM
Dalantech
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p.1 #4 · F-stop theory question


amacks wrote:
How is magnification described for that formula? is it the usual macro 1:1 as a fraction or
A


Just as a whole number, so 1:1 would be 1, 2:1 would be 2, etc.



Nov 03, 2009 at 02:33 PM





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