Sunny 16 Rule for Celtic Lands

 I've been away trying out exotic film stocks for a while and I decided it was time to post something photographic.

One of the things I have been thinking a lot about is taking film shots with old cameras that lack built in light meters. These cameras were designed to be used without such a thing and, if you get hold of a Kodak camera manual from the 50s or 60s you'll see how folk took good pictures with them.

The basic Sunny 16 rule that was used to judge exposures, worked pretty well for most situations that relied on natural light. If you found yourself indoors or taking pictures at night, the recommendation was to use a flash.

So the Sunny 16 rule as set by Kodak, based in Rochester, NY, at latitude 43°N, goes like this.

  • Set the shutter speed of the camera to match the ISO rating of the film. For example, if you are using Fomapan's 200 ISO Creative film, set the shutter to 1/200s.
  •  Look at the sky.
    • If the sun is shining brightly in a clear blue sky, set the lens aperture to f/16 (hence the Sunny 16 rule).
    • If it is a bit hazy, set the aperture to f/11 (one f-stop more than f/16).
    • If it is actually cloudy but still bright, set the aperture to f/8.
    • If it is completely overcast, set the aperture to f/5.6.
  • Check the location.
    • If the subject is outside but under shade, increase the exposure by one f-stop. For example, if it is hazy but the subject is sitting under a tree, don't use f/11, use f/8.
    • If the subject is indoors but lit by a window, increase the exposure by two f-stops. For example go from f/16 (sunny outside) to f/8.
    • If the subject is in a particularly bright location, like on a sandy beach or in a field of snow, decrease the exposure by one f-stop. So a sunny day on the beach needs you to go from f/16 to f/22. Some old cameras can't go to f/22, so you leave the aperture on f/16 and speed up the exposure by one f-stop. So, the 1/100s that is set of an ISO 100 film would become 1/200s on a beach or out in the snow and the aperture setting would remain unchanged.
    • If the subject is side-lit, increase the exposure by one f-stop.
    • If the subject is backlit, increase the exposure by two f-stops.
  • Check the subject
    • If the subject is bright (a person wearing white clothes for example) decrease the exposure by one f-stop. So, on a cloudy day, go from f/8 to f/11.
    • If the subject is dark (black clothes) increase the exposure by one f-stop, like f/8 to f/5.6.
  • You also have to allow for how high up in the sky is the sun. So the golden hour near dusk or dawn can demand an increase of  two f-stops from the basic rule and one f-stop is needed in the late afternoon or early evening.
And there you have it.

Now, I don't live in sunny continental climate up-state New York. I live in semi-Scandinavian Scotland at almost 60°N. The sunny 16 rule is actually calculated assuming the sun is directly overhead as if you are on the equator at noon. At 60°N, the sun's light illuminates the ground only half as bright as it would in the tropics. So it's like applying the morning and afternoon correction to the original rule. The basic table of f/numbers needs to start at sunny 11 with f/11. Not so easy to memorise.

There are also another few tweaks to add in the Celtic lands which are home to many levels of rain. When it is overcast and actually raining you lose some light too. This is why 400 ISO film is very popular among Celtic film photographers. 

So, as a service to film photographers visiting Scotland, Ireland and Wales, I present the Celtic film photography guide to exposing film.

  • Set the shutter speed of the camera to match the ISO rating of the film and then slow it by one f-stop. So 100 ISO film exposes at 1/50s, 200 ISO at 1/100s and 400 ISO at 1/200s.
  • Look at the sky and consult this table to set the lens aperture:

f/16    Sunny clear sky 

f/11    Hazy

f/8    Cloudy bright

f/5.6    Overcast

f/4    Overcast with smir (a cross between rain and mist)

f/2.8    Overcast with showery rain

f/2    Overcast with Glasgow Fair rain (enough to flood road junctions within 30 minutes) 

 Any worse and you should be seeking shelter, not taking photographs.

  • Adjust as usual for location, subject and time of day.
So, welcome to the Celtic lands and enjoy your photography. 



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