The Pentax Forums has a dedicated group of members that swear by the Sunny 16 method of estimating exposure. Often enough the topic comes up in the context of meterless film cameras, but sometimes in regards to well-metered and highly automated digital cameras, particular if adapted lenses are in the mix. The common mantra might be "Sunny 16 is all I need".
For those that are still reading, there might be some question regarding the "Sunny 16" rule and how it is used. The basic rule goes something like this:
Sunny 16 Rule:Assuming bright midday light, shutter speed at f/16 aperture will be 1 over the ISO sensitivity/film speed.
Example:
At ISO 100, the shutter speed for f/16 would be 1/100s or whatever is closest. At f/11, the shutter would be 1/200s and so on.
There is a similar rule for photographing the face of the moon. It is called the "Lunny 11" (Looney 11?) rule and is based on the average albedo of the lunar surface in full sunlight. Of course, it is always in full sunlight.
That last brings us to underpinnings of why sunny 16 works.
Sunny 16 is just a different way of saying that midday light is about LV 15*
As such, there are extensions to Sunny 16 for any number of lighting situations where a particular LV is more or less characteristic. A good example of how far this can be taken might be Fred Parker's "Ultimate Exposure Calculator" Web page (
LINK).
About now, the more analytical reader will be thinking that Sunny 16 sounds hokey. How can a simply calculation work everywhere? The short answer is that it doesn't. Sunny 16 in its basic form only works in the lower-to-middle latitudes. When the subject comes up here on Pentax Forums, it is not unusual for folk that live in my region to joke that Sunny 11 is the best we usually manage with Sunny 8 being more common. Part of the reason is latitude and another part is a tendency to have high clouds even when the day is bright.
With that in mind, it occurred to me that it was summer solstice this last Saturday, June 20. The day was cloudless and I had enough time before solar noon to see if Sunny 16 would work at least once in the year. Good fortune was on my side as I took a reading of a slab of gray concrete at high noon and had it come in exactly at Sunny 16!
Yay! It works!
Steve
* LV (Light Value) is simply EV for ISO 100
Last edited by stevebrot; 06-25-2020 at 10:00 PM.