Saturday, June 14, 2014

Exposure w/o Metering - Part 1

This will be a multi-part story about the technique of taking properly manually exposed photographs without the use of any light metering device.

30+ years ago, I heard about the technique called "sunny 16". However, being relatively young that time, with film being expensive and a heavy burden on my pocket money, I did not dare to use it, in particular since I was mainly shooting color slide film, which demands spot on exposure.
Consequently, I bough a relatively inexpensive light meter, a "Gossen Bissix 2" which did a great job, I still have it to the present day.
The light meter was used essentially only to measure the illumination, not the light reflected from the scene, thereby being independent from the color/brightness of the scene itself. Actually, I bought the light meter for exactly that, not sure if I used it ever for metering the scene itself.

Although the light meter did a great job, it costs additional time to take an accurate meter reading. Some shots were gone before the lighting was determined. To the time of expensive film, I thought "tough luck, no photo now, more luck next time"...

Today, I do not rely on pocket money any longer, I got my own income now ;-) So I decided to finally buy a camera which is able bring back the good old manual times, Fujifilm's X100S. The X100S is probably the best camera I ever owned, for sure it is the best compact point&shoot available on the market, which is definitely reflected by it's financial resistance, being somewhat a short circuit in the wallet.  Right, today, I could even afford to shoot more film, but where can you buy film today?!

Back to the topic: the "sunny 16" rule.

Exposure
The rule is pretty simple:
  • On a sunny cloudless day,
  • mid day between 9am and 3pm local time,
  • the exposure time is the inverse of the ISO sensitivity
  • at an aperture of f/16
  • when the sun is directly behind the photographer.
What does that mean? In essence, this is what a light meter does, when used for measuring the illumination of a scene. A light meter, with the diffuser/filter closed, pointed at the sun a mid day on a cloudless day, should read f/16 for 1s/100 with an ISO of 100. In the film days, ISO100 was a pretty normal film to use. A shutter time of s/100, however, did not exist. The closest to s/100 is s/125, which consequently is the shutter speed in this example.

However, there might be adaptations to this rule, e.g. if you wanted a shallower depth of field. Using an aperture of f/16 creates a very wide D.o.F., which is good for landscape photos, but may ruin a portrait. With a camera of those days, the shortest shutter time was s/1000, which would reflect an aperture of f/5.6 for an exposure equivalent to the example above, creating a shallower depth of field however.

Depth of Field
In general, whenever you need to open the aperture by 1 stop, the exposure time needs to be divided by 2.
  • f/16 - s/125
  • f/11 - s/250
  • f/8 - s/500
  • f/5.6 - s/1000
The above aperture exposure time pair will result in the exact same exposure of the image, however, the depth of field will be very different.

So far, so good. I will end this post here, w/o any example pics...

Some of the constraints metioned, I will write about in further parts of this series. I also intend to show examples shot with the X100S with manual settings.

For now, I would like you to absorb the rule "sunny 16" and the equivalence in exposures.

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