Brushing Up on the Sunny 16 Rule

With digital cameras today, there's almost never a need to “guess” or estimate exposure settings. Even so, you may eventually find yourself having to ignore your light meter and take the situation into your own hands. Or perhaps you'll end up falling for film and buying an old camera without a light meter. Either way, having the ability to set exposure without the assistance of a meter is a good skill to acquire.

USING THE SUNNY 16 RULE

1. Gauge Your Light
   For the Sunny 16 Rule to work, you'll first need a sunny day. The rule can also work with other lighting situations such as cloudy and overcast — take a look at the next list for those.
2. Set Your F-Number
   Set your f-number to f/16. If you don't have strong sunlight, use the next list to determine your starting f-number.
3. Set Your Shutter Speed
   Take note of your ISO or film speed (let's call it “X”). Now set your shutter speed to 1/X. So at ISO 400, you'd use a shutter speed of 1/400 seconds.
4. Adjust With Reciprocals
   You may want to use different shutter speeds or f-numbers. You can adjust one as long as you adjust the other accordingly. Opening up by one full f-number requires cutting your shutter speed in half (and visa versa).

VARIATIONS ON SUNNY 16

1. f/16 for Sunny
2. f/11 for Slight Overcast
3. f/8 for Overcast
4. f/5.6 for Heavy Overcast
5. f/4 for Sunset

F-STOP GUIDE

Since most cameras offer full stops, half stops, and third stops, you'll need to have a handle on which ones are full stops so you can use the rule of reciprocals to change your f-number and shutter speed. Here's a list of full f-stops.

f/1 – f/1.4 – f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11 – f/16 – f/22 – f/32 – f/45

But you don't need to memorize these numbers — there's an easy little trick to them. You actually just need to remember two numbers: 1 and 1.4. These are the first two full stops in the list. Double them and you get the next two in the list. Double those and you get the next two numbers. Check it out:

1.0 – 2.0 – 4.0 – 8.0 – 16 – 32
— 1.4 – 2.8 – 5.6 – 11 – 22 – 45

You'll notice that twice 5.6 isn't exactly 11 and twice 22 isn't 45. This is because the bigger numbers are rounded and the starting number isn't exactly 1.4 — it's 1.41421356… or the square root of 2.

Further Reading

Here are some additional resources having to do with Sunny 16 Rule and exposure.

• Sunny 16 Rule on Wikipedia
• Sunny 16 Rule on Camera Review
• Understanding Exposure on Luminous Landscape
• Exposure Demostrated on DIYPhotography.net
• Exposure and Stops on dPS

The rule really works — if you don't believe it, go try it out with any camera that has manual controls. I've been using the rule with my 1956 Minolta Autocord Twin Lens Reflex (no light meter) and it performs flawlessly.