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MillimeterIntroducing Leitner's Cinematography Corner
Oct 9, 2009 12:00 PM, By D.W. Leitner
Interchangeable lenses on a 1/3in. camcorder.
Editor's note: This is the first of D.W. Leitner's columns on cinematography. Check back each week for reviews, blogs, notes, and opinions from our longtime contributing editor, who is also an award-winning director, producer, and cinematographer of independent films showcased at film festivals like Sundance and Berlin. Check out Leitner's Cinematography Corner in its new home
Digital is not a cause. Not the shortcut some have made it out to be. It is a present-day means to innovation, that's all. Not an end in itself.
The Cinematography Corner will be my ongoing effort to steer discussion of new technology away from starry-eyed worship of all things digital and back to established filmmaking practices. We live in a solid-state world from which there's no turning back, but with these short entries I intend to build on a century of cinematographic art and craft rather than throw the baby out with the bathwater.
Back in the late 1970s and 1980s when documentaries and indie features were shot on 16mm, it was conventional for an Arri SR or Aaton owner to possess a basic lens package of two zooms plus a fast wide-angle prime lens. Typically this included a wide-angle Angénieux 9.5-57mm zoom, a longer Angénieux 12-120mm zoom, and a 5.9mm T/1.9 Angénieux prime or, later, 9.5mm T/1.3 Carl Zeiss Super Speed.
The reason for the wide-angle prime is obvious: to have a fast lens that can deliver a wider angle-of-view than either zoom can. But why two zooms?
No single zoom can be truly wide-angle at one end and truly telephoto at the other.
Now as then, wide-angle zoom design is an optical challenge, which is why they're less common and more expensive. But simply increasing zoom ratio is no solution either. A mild 3x zoom (sometimes called a "variable prime") will always yield higher-quality images at a faster aperture than a 10x zoom, which in turn will always outperform a 20x zoom. To bend these rules requires weight, size, and intricate design—i.e., use of fluorite elements, exotic glasses, and complex aspheric surfaces—which entails cost.
If you shoot documentaries, you need a wide-angle zoom for close coverage of people or large architectural interiors. If you shoot stage performances or sporting events, you also need a longer zoom for close-ups of faraway action.
Shooting 16mm in the early 1980s, the answer was a pair of zooms, as noted above. By the late 1980s, 2/3in. zooms for pro ENG camcorders got around this problem by incorporating a 2x extender, which was a built-in glass diopter (single lens element) flipped into the optical path at the rear of the zoom to double its focal lengths. Using the 2x extender, an 8.5-119mm ENG zoom became 17-238mm.
Convenient, no argument, but why didn't 2x extenders show up on 16mm zooms? Degraded optical performance, that's why—including loss of contrast, resolution, field evenness, and introduction of color fringing. Easily gotten away with in low-resolution NTSC, easily visible in higher-resolution 16mm and today's HD.
Continue the discussion on “Crosstalk” the Millimeter Forum.