Magazine article American Cinematographer

Cine-Style vs. Still-Style Optics

Magazine article American Cinematographer

Cine-Style vs. Still-Style Optics

Article excerpt

Welcome to Shot Craft, ACs new section for emerging cinematographers, which will focus on tools, techniques, and tricks of the trade.

In the world of photographic lenses, there are four major categories of optics: those manufactured for still cameras, those for electronic news gathering (ENG) or electronic field production (EFP) cameras, those for studio broadcast cameras, and those for cinema cameras. You'll rarely, if ever, see anyone trying to use a broadcast studio lens or an ENG lens on a cinema production, but the modern age has blurred the line between still and cine lenses. Thanks to the rise of HDSLR cameras and mid-range digital cinema cameras, the need for affordable cine-style lenses has opened the door for a new category of, relatively speaking, affordable cine optics. In addition, with large-sensor - i.e., larger than Super 35mm - digital cinema cameras, the demand for lenses with larger covering power is very high.

When newer filmmakers are investing in their first gear, the price tag of cinema-style lenses can be daunting and leave many questioning, "Is it worth it?"

The simple answer is: Yes. Let's talk about why. And for the moment, let's forget the glass itself and instead look at the differences between the two styles of lenses, focusing on what they're manufactured to do.

The first - and possibly biggest - difference between cinema-style and still-style lenses is the focus scale. Modern still lenses are designed to be compart and lightweight; they're also, primarily, designed for autofocus. And in order to meet the demands of modern DSLR cameras, they have to be super-fast at focusing. To realize that, the focus travel of the lens is cut down to a minimum so that the lens doesn't have to move very far to find focus.

Let's talk about this in terms of rotational degrees. In other words, how many degrees does the focusing ring rotate from minimum object distance to infinity? On many modern still lenses, this might be as little as 15-20 degrees, which is great for the autofocus mechanism as it means the motor doesn't have to rotate the focus movement far to find precise focus. However, for manual focusing, this can be a nightmare. With such a limited degree of travel, there's only space for a few distance markings on the lens - if the lens has markings at all! These days, many still lenses don't even have a visible focus scale, as they're 100percent autofocus or focus-by-eye; when they do have a scale, you might only find markings for 4', 7', 20' and infinity, which doesn't exactly allow for precision.

When you're shooting a fairly close subject at a wide aperture, your depth of field can be as small as an inch (or less), and there's no way to know where 5'2" falls between the 4' and 7' markers. Furthermore, if the subject moves - which sometimes happens in motion pictures - adjusting critical focus based solely on the focus scale of the lens is nearly impossible. Even if you're adjusting focus by looking at a sharp image on a monitor, the focusing ring's degree of travel is so small that keeping the subject sharp is an absolutely Herculean effort.

Enter the cine lens. The first thing a cine-style lens does is to significantly expand the focus scale and its rotational degree. Many modern cine lenses now have 300 degrees or more of rotation on the focusing ring. This allows for substantially more room for calibrated markings, especially in the dose-focus distances. You'll often see cine-style lenses marked for 3', 3'3", 3'6", 3'9", 4' and so on. The expansion of the focus scale and addition of critical focus marks make it considerably easier to find focus and smoothly hold and adjust focus as your subject moves. Note that there isn't a difference in the amount the optical elements within the lens actually travel; there is just a compression or expansion of the amount of travel of the focus control. Think of it like a gear system where the full rotation of a small gear might move a larger gear only a fraction of its full circumference. …

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