Light, as much in photography as in movie-making, is the foundation of our work. We have to work with light, know all of its secrets, and learn techniques to manipulate it. This is why it is essential to learn as much as we can about the technologies available to us. In several other articles, we talk in detail about light and its use on set, exploring topics such as different types of lights, and differences between cinematographic and photographic lighting. Here, however, we focus on mastering camera operations, not so much for technical reasons, but rather for the infinite expressive opportunities they offer.
1. A camera sensor
2. A roll of film as used in certain movie cameras
A first important clarification to make is the difference between digital and analog cameras. We can see the digital camera as the evolution of the analog camera. Indeed, film is gradually being replaced by digital sensors, using technology we continue to invest in, with progressive and continuous improvements in performance. However, photographic film has not yet been replaced altogether, and still has many fans. In any case, it is essential to understand both media. So let’s focus our attention on four aspects at the foundation of the photographic technique:
- Film or digital
Film or digital media?
Let us start by listing the merits and defects of both film and digital media, in order to get a first glimpse of the revolution in act of recent years.
Advantages of film:
- Different formats
- Higher equivalent resolution than digital
- Long lifespan (around 500 years in black and white, 150 in color)
- Pleasure of handling a physical negative
Disadvantages of film:
- Higher cost
- Laborious to develop
- If you get a shot wrong, you waste film
- Limited number of shots
Advantages of digital:
- High reproducibility
- Virtually unlimited number of shots
- Easy post-production processing
Disadvantages of digital:
- Relatively lower resolution
- Lifespan depends on the digital media on which it is stored
- There is no physical negative to handle
This term, also referred to as ‘speed’, represents the sensitivity of the film or sensor to light, generally classified as Slow, Medium, Fast or Ultra-fast, as indicated below:
- Slow: ASA rating no higher than 50
- Medium: ASA rating between 50 and 160
- Fast: ASA rating between 160 and 800
- Ultra-Fast: ASA rating above 800
A slow film requires more light in order to register an image, meaning that exposure time must also be greater. On the other hand, it produces excellent definition, and the resulting image can be enlarged considerably without loss of detail. Conversely, the main advantage of using ultra-fast film is that it requires very little light, though there is a risk the image may appear to have a ‘grainy’ quality, whose digital counterpart is referred to as ‘noise’. Without dwelling on the technical definition of ‘graininess’, suffice it to say that it results in a lack of clarity in the image.
On a digital camera, sensor sensitivity can be quickly and easily set in camera settings. The basic principle remains the same, the lower the sensitivity, the greater the required exposure or quantity of light. The jump from one sensitivity setting to another almost always corresponds to twice the value of the previous one, with sensitivities commonly expressed in ISO values, such as 100, 200, 400, 800, 1600, 3200, 6400, and so on.
The shutter is the camera’s opening and closing mechanism, controlling exposure time, the time light is allowed to pass through and fall onto the film or sensor. This time, referred to as ‘exposure time’ or ‘shutter speed’, is measured in fractions of a second, with standard values such as 1/8000, 1/4000, 1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1s, and so on.
Aperture is the mechanism regulating the amount of light passing through the camera while the shutter is open. This variable is expressed as the ratio of focal length to aperture diameter in ‘f-numbers’, usually marked on lens rings with the letter ‘f’. F1 indicates a fully open aperture, f22 an almost entirely closed aperture. The transition from one aperture to another is referred to as a ‘stop’. Photographers generally think in transitions of 1 stop, or ½ at most, while cinematographers are used to thinking in thirds of a stop, which explains the use of the letter ‘t’, instead of ‘f’, on video camera lenses. This setting also affects the so-called ‘depth of field’, the area of an image in which objects are in focus. As the f-number increases, the depth of field also increases, meaning that despite offering opportunities for artistic effects, a compromise between the quantity of light and depth of field must be sought. Indeed, on each transition from one f-number to another, or one stop to another, the light entering the camera doubles. The greater the aperture, the greater the light intensity, but the shallower the depth of field.
The same effect can be seen in the iris of the human eye. In low light conditions, the iris is completely open, allowing clear vision up close but sacrificing clarity at a distance. Conversely, the greater the amount of light, the more the iris will tend to close, offering better vision of objects at a distance.