13 The light meter doesn’t work. Now What?



  • Learn how to use the F 16 Rule
  • Download a light meter app on your phone

What is the Sunny 16 rule?

Sunny 16 or F 16 Rule

Sunny 16 rule allows the photographer to determine the correct exposure while shooting outdoors with natural daylight. You can estimate the correct exposure without a light meter.

The rule says: On a sunny day (distinct shadows) set your F stop at F 16 and your shutter speed at the number closer to the ISO (film speed) you are using.

For example, if you are using 400 ASA film your correct exposure on a sunny day is:

F 16 @ 1/500 (F-stop 16 and shutter speed 1/500 sec)

If ISO is 200 (F-stop 16 and shutter speed 1/250 sec)

If ISO 125 or 100 (F-stop 16 and shutter speed 1/125 sec)

Make sure you are photographing with the sun on your back and not facing the camera.

Why is it useful?

This is a great rule to understand and apply when you photograph outdoors during daytime with natural light. It works very well and you can bracket your exposures, which means taking a few extra photos of the same scene by making exposures + one or – one stop.

” During the day, I don’t need a light meter. It is only when light changes very quickly at dusk or when I’m in another country, in the desert, or in the snow. But I guess first, and then I check. It is good training.” Henri Cartier- Bresson

When you use the Sunny 16 rule you ignore what your light meter is telling you to do. Set your camera to manual mode.

Reasons you may have to use the F 16 rule:
  • your lightmeter is not working properly
  • your camera doesn’t have one or it is out of batteries
  • you’re just interested to understand lighting and doing it yourself
 Soon you will look out your window and instead of saying “It’s a sunny day ” or “a cloudy day” you will smile and say it is a sunny F 16 day …… or frown and say it’s a nasty F 4 day.

Light meter Applications on your phone

Download Light meter apps on your smartphone.

There are many free to download  but we suggest you pay about $10 to get a reliable one and skip the advertisements.

A good one we use is: Pocket Light Meter for IOS and Lux Meter for Android.




Icon for the Creative Commons Attribution 4.0 International License

Photography: What, How, Why Copyright © 2023 by Maria Politarhos and Randy Matusow is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

Share This Book