Mark S Abeln
Forum Pro
That's what I was thinking, as film speed definitions didn't stabilize until quite late in history.
According to Google books search, the earliest occurrence of the phrase "sunny 16 rule" is in 1980, by George Thomas Yeamans, and it was frequently repeated throughout the 1980s and 1990s.
This does not mean that the rule didn't appear in magazines, newsletters, or in conversations before 1980, or in some book not digitized and indexed by Google, nor does it mean that some variation of the phrase wasn't used, although searching for "sunny sixteen" or "rule of sunny 16" didn't come up with anything earlier.
I couldn't find anything before 1980 that referred to "sunny 22" but of course that isn't proof that the rule didn't exist
*****
There is an interesting rule of thumb from the old days, the "One, Three, Five, and Double Rule" or "1-3-5-10 rule" for outdoor exposure. Basically, take the shutter speed settings needed for a bright sunny day, and multiply that by 3 for a hazy day, 5 for a cloudy day, and 10 for an overcast day. This is found in American Photography, Volume 19, from the year 1925. Obviously this doesn't tell you what all your settings ought to be, but if you already have a good exposure for one, you can guess the others. It was noted that these values weren't quite accurate, but close enough.
Tabulated exposure values, such as found in a Wikipedia article, have a somewhat different series, 1-2-4-8, which gives a fractional stop difference of exposure from the 1-3-5-10 rule in each cloudy situation. The 1-2-4-8 rule is what's found printed inside of many Kodak film cartons, although there are variations—sometimes the "2" for hazy conditions is omitted, or sometimes varying shutter speeds are shown, with faster speeds for sunny conditions, or sunny beaches and snow.
I don't think you have wrapped your head around the idea behind Sunny 16, though -- it's not about setting exposure at f/16, it's about understanding scene luminance.
