Light meters and DOF

J

Jackooo

Member
Hi,

A question i have always wondered.... say for example i go to shoot a scene on film and take a light meter reading and for example the light meter says to set me shutter speed 1/350 and the apeture at 5.6 giving me a shallow DOF, what is the rule about adjust the iris.... say to 11? what would i have to set the shutter speed at?

Thanks!!
 
Lets make it simple. If the light meter says you need 45 degrees of shutter for f5.6 you would need twice as much light for f8 or four times as much light for f11 In other words 90 degree shutter or 180 degree shutter opening. Each f stop is either twice as much light or half as much light depending which way you change it . Same for the shutter.
 
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And to simplify this even more, you would never really adjust your shutter in correlation to t-stop, when shooting film. The only time this would happen is if you are going for very dramatic effect. Still however, it is nice to know the fundamentals of the formulas.
 
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