I work with scientific imaging systems as well as commercial video cameras.
There is a distinct qualitative difference between programs shot on video and those shot on film. Most people can tell the difference, but not everyone notices it consciously. The lighting is indeed the most noticable factor, but because of the technical differences between film and video, the lighting requirements are different.
Modern videotape cameras are exclusively CCD cameras. The sensors convert photons to electrons with a linear response, i.e., the signal at each pixel is directly proportional to the number of photons received at that pixel on the sensor. After accounting for offsets and defects on the sensor, the number of electrons out divided by the number of photons in is a constant number.
Film cameras, on the other hand, use a photochemical emulsion on a clear substrate, e.g., film. The change in the opacity of a spot on the film is not linear, but logarithmic… ie, as more photons hit the same grain of emulsion, that grain changes opacity a little bit less. The first few photons change the opacity of the developed film more than the last few will.
This difference is important. It means that film can have a much greater dynamic range, or in other words it can record a much greater range of light and dark levels. This is also similar to how the eye responds to light, so it looks more natural. It also provides the director with a lot more options in how to light a scene and establish a “mood” in the scene.
The quality of film also provides more control to the director. The director has a wide choice of film stock, with different sensitivity to light (speed) and different responses to color (look at Three Kings vs Twelve Monkeys, or for Boomers, Duel in the Sun vs. Midnight Cowboy). These kinds of effects can be simulated on videotape, but they can’t match the impact of the effects from real film stock variations.
Different speeds of film also have different size “pixels” of emulsion, called grains. When they are large, you can almost make out individual grains… thus the “grainy” look. Additionally, these grains are randomly arranged and oriented, as opposed to the pixels on a CCD, which are all uniformly sized and shaped, and in an ordered rectangular grid. Thus, the CCD is susceptible to “aliasing” like when the local weatherman wears a checked tie and the image of the checks on the image sensor is about the same scale as the sensor’s pixels… resulting in that wild and crazy psychedelic effect.
Most TV dramas are shot on film and then transferred to tape for editing and broadcast. If digital effects are required, the film is digitized and then recorded to videotape after the computer effects are added.
Finally, the description of videotape being more “real” is entirely subjective. Part of it is the sharpness that is provided by the stark, flat lighting. It’s also a conditioned reaction, since most news stories are shot on video, whereas works of fiction are typically shot on film.
