Exposure

Here is a little basic noting I did on exposure from Cinematography: Theory and Practice by Blain Brown.

• Light is measured in foot candles (fc) or lux. A foot-candle is the light from a standard candle at a distance of one foot. One lux is the illumination produced by one standard candle from a distance of 1 meter. Typical T.V studios are about 1000 lux or 99 foot candles whilst a bright office has about 400 lux of illumination or 40 foot candles.
• The f/stop controls the size of the aperture on a camera and it measures in stops, a stop being a unit of light measurement. An increase in the amount of light by one stop means that there is twice as much light. A decrease of one stop mean that there is half as much light.
• F/stop numbers are actually fractions as they describe the ratio of the lens' focal length to the diameter of the entrance pupil so f/8 actually means 1/8; the diameter is 1/8 the focal length.
• Light becomes more intense, the closer one is to the light source. For example if the lamp is 10 feet from a subject increasing the distance from the subject to 16 feet will decrease illumination by two stops. This is called the inverse square law.

Below is what happened when I decided to play around with exposure. I set up my subject with an 800w readhead, five foot up, about 12ft away at an angle of about 30 degrees to his right. I started at f/2.8 and worked down in half stops to f/5.6. The light was also set to flood and the camera was set to 1080/25p with a 1/60 shutter speed.

I then did the same but this time with another 800w light. This time 5 feet up, about 10 feet from the subject and about 5 degrees to the subject's left.

After doing these shots I realized it wasn't about trying different exposures it was more about learning how to find the correct exposure.

• With incorrect exposure: the shadows may appear too bright and the highlights will appear too bright or "blown out" or the shadows will be too dark and not show enough detail and the highlights will appear too dark and only be a grey midtone.
• Correct exposure is about setting the f/stop so that it sits directly between the brightest highlight and the darkest shadow. Of course in scenes where the highlights and shadows are far apart this becomes problematic.
• A typical scene has seven stops of brightness; a contrast ratio of seven. Part of a cinematographer's job is ensuring that there is a suitable contrast ratio and setting the f/stop in the middle.
• Controlling the contrast is therefore mostly in the lighting techniques (hence why I bought that book).
• A good thing to remember is that white caucasian skin is usually about one stop lighter than the middle of the greyscale of a scene.

Here is a trailer for film Archipelago. The film is pretty poorly lit, especially for a full length feature. The whites are frequently blown out/close to being blown out and there are large patches of darkness in all the wrong places. The entire film is lit very flatly too. This film is of course designed to be highly realistic, capturing family life as we know it and the lighting does go well with the realism. In this film there are no great hurdles to overcome or crises to battle with, there are only a variety of disputes and discomforts, i.e a realistic representation of modern family life. I for one can't stand the lighting, it just makes me feel uncomfortable and tense. I suppose also that I probably don't like it because it goes hand in hand with the script which is so realistic it's boring and ultimately pretentious.