TECHNICAL DIFFERENCES BETWEEN DIGITAL AND FILM CAMERAS
Traditionally, film cameras had set shutter speeds, usually from 1 second to 1/1000second. These were timed with a spring shutter, which did not allow interim settings between these speeds.
Lenses for film cameras, pre-auto focus, usually had a ring to set apertures, which often had clicks for making stop and half stop settings.
ISO (ASA) settings on film cameras are for film speeds. These are calibrated in 1/3 stops, since some films (e.g. Ilford FP4: 125 ISO) are not made at whole stop settings. The same ISO must be used for a whole film, but can be changed in digital cameras according to the light value present.
Film camera lenses were first made in prime focal lengths, ie. without zoom. The standard lens for 35mm cameras is 50mm, which gives the same angle of view as the human eye (45 degrees), and also shows the same perspective (for relative distances of different subjects) as the human eye.
NB: since the size of consumer digital cameras is 1.5x smaller than ‘full frame’ (whole 35mm film format), the ‘standard’ lens for these cameras is also 1.5x less than 50mm, or around 32mm. BUT: since 35mm constitutes a wide angle lens, which has the characteristic of exaggerating perspective, there is still more perspective distortion with a ‘normal’ focal length lens on a small chip camera, compared with a full frame camera system.
White Balance (WB) is the correct colour balance of the image relative to the colour temperature (degrees Kelvin) of the ambient or flash light source in the scene. Colour film is available only in two white balances: daylight and tungsten (changes for other light sources have to be made with lighting or camera filters). Digital cameras have settings for individual light sources; sun, cloud, overcast (shade), tungsten, florescent, flash and preset or custom, as well as auto white balance.
Film cameras record data on the film at one quality setting, usually relative to the ISO of the film (lower ISO films record finer colour and sharper detail). Digital cameras can be set to different File and Image sizes (quality), though it’s best to record data at the highest quality setting. Film also records colour, sharpness, saturation and contrast relative to the light source and subject, but digital cameras can be set at different ‘perameters’ or ‘picture styles’ for these characteristics.
Digital cameras offer features with the review image of photos just taken, including auto rotate and magnifying the image detail. Since film images are not available for viewing or printing until the film has been developed, there is no way to see or review the final image from a film camera before this stage. Professional photographers shooting film often use instant ‘Polaroid’ camera backs which allow them to review this image, though usually this isn’t available on 35mm format cameras.
Film records tone and colour most accurately using exposure to calculate shadow detail and development to render highlight detail. Digital media only has one process in exposure, except that shooting in ‘Raw’ (unprocessed) format allows for greater adjustment of things like exposure and white balance. It’s thought that film, properly exposed and processed, shows a greater tonal, colour and contrast range than digital for this reason, especially in black and white.
© James Bartholomew 2009
Email: james@jamesbartholomew.com
Photography Made Simple 
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