If you know about the Sunny 16 Rule, also called the Sunny f/16 rule then you’ve either been in photography a long time or are a student of the craft.
Sunny 16 is older than most of you reading this and reaches back to a time when the light meter was hanging around your neck instead of being inside the camera. It is one of those old standards slowly being consigned to history by the introduction of multi-point intelligent metering systems, though it will still be relevant to people serious about learning manual photography.
For those of you determined to learn manual shooting, and I salute and encourage that desire, Sunny 16 is how you get your settings in the ballpark for shooting outside. The rule says for outside in full daylight start with f/16 and set the shutter speed to the inverse of your ISO.
So outside in the sun, start with f/16 and if you’re using ISO 200, set your shutter speed to 1/200th of a second. If your ISO is 400, then use 1/400th of a second and so on.
It’s one of those guidelines that every old photographer knows and is fairly accurate for outdoor exposures. You can even use it as a starting point for partly cloudy and overcast days. For a partly cloudy day you might keep the ISO/shutter speed the same and open the aperture to f/11. For a cloudy day go with f/8 or, if you’re worried about depth of field, leave the aperture at f/11 or f/16 and cut the shutter speed in half. So for a partly cloudy day you might leave the aperture at f/16 and the ISO at 200, but use 1/100th of a second shutter speed instead of 1/200th for a sunny day.
Also keep in mind your shutter speed selection can also depend on your lens. If you have a 300mm lens, you don’t want to use a shutter speed less than 1/300th of a second to avoid motion artifacts. For a 500mm lens your lowest shutter speed would be 1/500th of a second. Make adjustments to the other variables accordingly.
Set your camera on “M” or manual mode and give it a try, I think you’ll find it’s kind of fun. You might even catch yourself leaving the camera set to “M” for progressively longer periods of time.
DSLR cameras today are marvels of sophistication and yet, for so many photos the “perfect” exposure is not always the most technically accurate one. So far no camera manufacturer has figured out how to duplicate your creative genius and I don’t think they ever will.