Experience with Sunny 16
I'm sure this question has come up before, but I would like to hear different folks' experience with the Sunny 16 rule. I lived in Pennsylvania when I first became aware of exposure, and nothing was ever Sunny 16. The best you could hope for with the sun directly behind you at mid-day was Sunny 11; Sunny 8 was pretty common. Then I moved to Texas, and the summer sun directly behind would meter f16, but f11 was still more common. On trips to the Rockies, the Sunny 16 rule (as displayed on the back of my Olympus S II's) worked out right, and I could feel the increased sun's intensity on the back of my neck. I also saw f16 on trips to Hawaii. So for many years I was content to interpret Sunny 16 as a "brightest possible sun" rule, often seen in the tropics and a mile or more up in the Rockies, occassionally seen in Texas, never in Appalachians.
I recently got back from a trip to England, in September. Two weeks before the equinox, at latitudes above 50 degrees, essentially at sea level I was concerned that the 100VS film would be pushing its practical limits. But the meter showed otherwise. England was metering a full stop faster than I would have expected in Texas. The processed film proved the meter was correct.
What have other people observed about Sunny 16 at various locations?
There's sun in England? Wow!
Sunny 16 works here but I use a meter.
Here in Tasmania I have had reasonable success with sunny 16 using neg film, both colour and mono bur haven't used it for slide.
I regularly get Sunny-16 in Australia, even when it's not summer. I found though that Europe (Prague and St Petersburg) was metering at about f/13 so I have a bunch of slides that are about half a stop dark. And even slight haze of high-level cloud will reduce the visible light here to f/11.
For a quick comparison of daylight (and UV) intensities, consider that you can spend a day in full sun in Europe with little or no effect, maybe the beginning of a tan and a bit of warm feeling in the cheeks. In Australia, that "warming" takes 10 minutes; an hour will get you a painful burn, 4 hours will burn you bad enough that you can't sleep and 6 hours will require hospitalisation. So there are definitely geographical differences in sunlight intensity, especially if you want to shoot (UV-sensitive) alt processes.
If there aren't any clouds at all, and the time is between 10 AM and 4 PM, Sunny 16 is certainly close enough for me to use with print film. It gets tricky here in winter though, with our usual snow cover. Then, it's Sunny f22!
Kent in SD
i usually get sunny 11 here in new england
but i don't really worry about rules cause
the reason they are there is to break'em.
my film doesn't seem to suffer, so i just
remember the light conditions and expose
according to experience, not steadfast rules
I live in England and yep, there is a sun up there somewhere...
As I understand it (and maybe I don't) the atmosphere acts as a big UV filter and the more atmosphere the sun's rays have to penetrate the less UV it contains. Consequently at higher latitudes when the sun never gets very high in the sky the rays have to penetrate a lot more atmosphere than when the sun is overhead in mid summer at the equator. This means that at the moment it would be impossible for me to get a sun tan (and my cyanotypes take ages) but I can walk about in the day time without bumping into things ;-)
When I went on a summer holiday to the Yosemite I over-exposed everything. Using my own calculated film speed and trusty meter I failed to allow for the fact that the brightest light at 9, 000+ feet in clear air that far south the light must have been much more actinic than anything I was used to...
I suppose it will also depend on the film and equipment you use. Maybe a lens with a lot of glass in it and a uv filter on the front might not show much difference compared to an unfiltered, uncoated triplet?
I usually go with sunny 11 on decent days here in Seattle - for those 3 months a year. There rest of the time I fall back to metering as I have trouble with the shades of overcast the rest of the year. ;)
I use the rule somewhat but mostly I stop up twice from whatever the rule tells me in sunlight. Then again, I don't really use the rule I just kind of get a feel for what the light is and follow my gut. Works most of the time. Most.