I had all but forgotten the
Sunny f16 rule. This technique was used with great success by photographers for decades.
I'm not going to explain the rule it's done on the link provided above. I Can say that if a beginner wants to learn how to manually set exposure, using this rule will move you in that direction very quicky. This rule isn't infallible it is however a great starting point for manually controlling exposure settings.
Above all it's very simple to understand and use:
- Recognize the type light you're photographing in
- Set you aperture according to the light you recognize
- Ensure your shutter speed and ISO match
There are considerations such as DOF, higher ISO needed, or a faster shutter speed to stop action but making those adjustments are as easy as counting clicks.
Example on a sunny day taking a portrait you may wish to have a shallower depth of field. If you just set your aperture to F4 to get the DOF you want without changing your other settings you'd get a beautifully blown out image.
Normally the rule is:
- ISO - 100
- Shutter Speed : 100
- f Stop - 16
Adjusting the rule to get a proper exposure will give you the same exposure as the rule above (for sunny) but with the DOF you want. if you change one adjustment you must move another in the opposite direction to maintain the same exposure.
Sunny F16 rule changed for DOF
- ISO - 100 (no change)
- f Stop - 4 (DOF)
- Shutter Speed to 1600
The above settings are the same exposure at ISO 100 (f16 & Tv 100 = f4 + tv 1600) you've just added DOF for the portrait. There is chart at the link above. As well there may be times when you need to increse or decrease exposure setting by a stop or partial stop to obtain proper exposure using the cameras meter.
As I said the rule isn't set in stone but it provides an excellent starting point as well as the opportunity to see how each adjustment interacts with the other.
Here are two samples both using this rule the sky photo required an adjustment to the ISO by 1/3 stop (my K30 is set up to allow the 1/3 adjustment) to ISO 125 to get the camera meter to the center position. These photo's are JPEG straight out of camera, resized, and a partial exif posted with a script.
They are for illustration purposes only: Very bright and cold day- the first just after noon and the second around 1:15 PM. In both cases I made the initial sunny and bright sunny settings in my home before going out to shoot.