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In a message dated 98-04-29 02:15:15 EDT, [EMAIL PROTECTED] writes:
> To clear up any confusion on why you lose exactly one F stop with a 1.4x
> converter and exactly 2 F stops with a 2x converter, you have to understand
> that this is from the light fall-off (the light has to travel a farther
> distance, and falls off as it travels and covers more area) from the
> increased distance from the lens to the film plane.
Dave's right about this, and the actual number is 1.414. It's a natural
logorithimic principle. To work it the other way, with audio one speaker will
give you so many decibels at a given distance. Add another identical speaker
producing identical sounds, and it will only be 1.414 times as loud.
This number and the math related to it is found throughout physics.
....Mike
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