Sunny 16 Rule

In class we talked a little bit about how to know where to set your aperture and shutter speed when taking photos in manual mode. Here’s a basic rule of thumb for shooting outdoors.


When caught without a meter, one can use the “Sunny 16 Rule” as a guide for exposure. There are two steps to the rule, as outlined below: 
STEP 1: Set your shutter speed equal to your ISO/film speed.  (i.e., Shutter = ISO/Film Speed) 
Please note that in most cases, the shutter speed will NOT EXACTLY EQUAL ISO/film speed, but will be set as close as possible to the film speed. It’s simply easier to remember the rule as “Shutter = ISO/Film Speed.” 
STEP 2: Set your aperture equal to f/16 for sunny sky. 
What if it’s not sunny? If slightly overcast, open one stop to f/11. If overcast, open two stops to f/8. If deeply overcast, open three stops to f/5.6.

How do I distinguish between slightly overcast, overcast and heavy overcast?

Examine the shadow detail. If shadows are distinct but soft around the edges, then it’s slightly overcast. If shadows are not distinct, but still visible – very soft – then it’s overcast. If there are no shadows at all, then it’s heavy overcast.

The chart below provides a useful summary: 


Lighting Conditions Shadow Detail  

Sunny   Distinct  

Slight Overcast   Soft around edges 

Overcast  Barely visible 

Heavy Overcast No shadows  

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