ENG and EFP
A typical ENG camera will come with a single ENG style zoom lens, which is designed to be used by a single operator. Thus, the focus ring on the camera will go from close focus to infinity focus with about 1/4 twist of the lens barrel. It works great for news shoots, largely due to the wide range of focus that a smaller 2/3″ camera lets you get away with. (The shot will look in focus even if you’re fairly far off on the focus setting.)
Cine-type lenses have a *lot* of focus ring travel, and are typically marked in very fine focus increments. They are designed to be used with a separate focus puller, a person who stands off to the side of the camera (or rides on the dolly along with the camera), and remotely drives the focus mechanism to make sure that the shot is focused. The ring on their remote focus device (we were using a Preston Cinema FIZ (Focus Iris Zoom) hand control) is marked with the same markings that are on the lens’ focus ring.
This is needed because the 35mm motion picture camera image causes a very narrow depth of field — if you’re not within a very close range, the shot will be fuzzy and the operator gets fired.
TV news always use zoom lenses, as they are very quick to set, but most feature film and episodic TV work uses a combination of zoom lenses and prime lenses. “Primes” have a single focal length: 15mm, 17mm, 24mm, 100mm, etc. A production will switch back and forth from one prime to another for various shots, going in for close-ups, etc.
A typical example would be starting out with a 18mm or a 24mm lens for the “wide” establishing shot, then switching to a 100mm or a 130mm lens for the close-up “portrait” shots. The longer lenses have much less distortion, so faces look more natural in close-up shots. If they used a wide lens, the actors” noses would look gigantic; not good.
Prime vs. Zoom
This of course begs the question — why don’t features just use zoom lenses if they are so quick? The basic answer is that until recently, it was hard to make a zoom lens that had the same quality as a prime lens, and even when you did they tend to be staggeringly heavy (60 lbs + for a modern Optimo zoom made by Angenieux.). This is fine on a crane or a jib arm, which is where you see the cine zooms with cine-style focus rings used, but in handheld or Steadicam type shots, the operator just can’t take the weight.
Prime lenses, since they just have a single focal length and far fewer “elements” (pieces of glass) in the lens, weigh less and make a better quality image than a cheap ENG-style zoom. They also have a lower F number and are thus “faster” — the F number tells you how much light makes it through the lens and onto the imager.
Faster lenses and higher camera sensitivities mean that you need to haul around fewer lights to get a good exposure, which translates to savings.
Typical ranges for modern digital cameras range from about 320 ISO for the Red, to 500 ISO for the new Arri. The next generation of cameras are coming in at the 1000 ISO mark, which was previously considered the domain of high speed film. The lack of noise and highlight handling in the new sensors make them extremely useful for compositing work, both in the greenscreen capture and in the background capture stages.