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Several images come to mind when the subject of lenses for sports coverage comes up: One is the extreme close-up of a player from a hundred or more yards away; the other is of a camera operator and his camera-lens combination, bundled up against a cold, driving rainstorm. Both define the challenges facing those who build lenses for sports coverage.
The largest zoom ratio lenses in use for sports today are at or just beyond 100x. In building such lenses the manufacturers face myriad hurdles—including the physical laws of light—to deal with.
(click thumbnail)A Canon DIGISUPER100xs, outfitted with the Vinten Vector 950.“The longer you go, the darker the lens becomes,” said Dave Waddell, marketing manager for Fujinon, in describing the need for more light to deliver a bright enough image to the camera’s sensors. Because that can take larger diameter optics, it can add tremendously to weight.
WHO’S ZOOMIN’ WHAT
Related to that is what’s known as f/stop ramping, where a zoom lens is more sensitive to light at the wide end of its zoom range than at the telephoto end, according to Gordon Tubbs, director of marketing at Canon USA.
“The more zoom ratio you add to a lens, the more ramping,” he said. “That’s pure physics.”
Two other factors weigh in as well. “With longer focal lengths, optical quality typically deteriorates due to chromatic aberration and diffraction,” said Jean-Marc Bouchut, technical manager for Thales Angenieux. Chromatic aberration is caused by different wavelengths of light bending at different angles as they go through lens elements; diffraction is the tendency of a beam of parallel light to spread out as it passes through a circular aperture, and is more pronounced as the lens is stopped down.
Overcoming these challenges takes a lot of careful design work and a lot of glass, creating the large box lenses seen mounted on cameras at sports venues. Optical engineers at all three companies are working to improve the quality of their long zoom-range lenses and reduce the size and weight.
But should we expect to see even longer zoom-range lenses in the near future? Tubbs at Canon and Waddell at Fujinon, which make a 100x and a 101x lens respectively, report that the limit may have been reached for the time being.
“I think from a lens format length aspect, versus cost, versus stability, I think that’s all we need to go for sports,” said Waddell. He noted that “even the larger sports trucks are not putting all maximum zoom-range lenses on their trucks, typically they drop back to 86x or 87x lenses for the rest of their big lenses.”
Tubbs said there’s nothing with technology today that would stop a lens to go further than that. “We don’t have any plans to do that now, but at some point in the future when the market re-quires it, or we think the market would require it, we could develop a lens that has a longer zoom-ratio than 100x,” he said.
(click thumbnail)Frank Lazar with NFL Films uses the Fujinon HA25x11.5 BE lens.Beyond the lens itself, there are limitations to what it takes to operate a long telephoto lens. “We can provide the telephoto power,” said Bouchut, “[but if the shots] reach a point where they can’t perfectly track the action, they can choose to shoot wider in order to keep the action in the frame.”
KEEPING IT STABLE
By their very nature, sports venues include tens of thousands of rabid sports fans, which can create vibrations in the venue structure that are transmitted through the camera mount to the lens itself, making it nearly impossible for the operator to hold a steady shot. The answer from lensmakers is lens stabilization.
Fujinon not only built stabilization into its longer zoom-range lenses, it also offers a sandwich stabilizer that can mount between a non-stabilized lens and the camera to bring stabilization to older lenses.
Canon has collaborated with fluid-head maker Vinten to develop interaction between the head and the lens stabilizer, “where their optical encoders talk to our lens, and help the stabilizer work better,” Tubbs said.
Information from the fluid head helps the stabilizer determine the difference between vibration itself, and an intended move of the camera by the operator, which allows the stabilizer to dampen vibration while keeping it from fighting the operator trying to follow the action.
Bouchet said Angenieux’s crystal ball shows “features that are now being developed would include greater interaction between the lens and the camera to optimize optical quality, in addition to a built-in electronic zoom function on the camera.”
All of this lens performance design would be for naught if the lenses couldn’t deliver great images day-in and day-out, year after year.
(click thumbnail)Token Creek Productions employs Thales Angenieux’s 62x9.5 AIF OB lenses aboard the company’s 30-foot mobile production unit “Millennium” for a variety of sports productions.“To be honest with you, that’s what makes or breaks long term relationships with customers,” said Tubbs. “If it can’t stand up to [tough day-to-day usage and transport], it doesn’t matter how good the lens is optically.”
Treatment of lenses and other broadcast remote equipment is a cultural thing, according to Waddell, and it doesn’t reflect well on those of us in North America.
“We have to make them very rugged, especially in the United States, where you have different people taking the lenses apart after each shoot, unlike in Europe, and moreso in Japan, where you have the same people doing it each time,” he said. “In Japan you’ll see they have white gloves on and they’re gingerly taking the lens off, placing it in the container and so on.”
By contrast, in the United States, “you have these freelancers who jerk the thing off and throw it in the box, throw it in the belly of the truck, and just leave.”
One practice Waddell noted—putting the lens away in a rain-soaked packing crate—requires just as much moisture-proofing as operating the lens in a rainstorm.
Tubbs says moisture is not as much of a concern at Canon. “All of our lenses that we build today are internal focus,” said Tubbs. “With internal focus systems, moisture and condensation are not an issue.”
Angenieux lenses are filled and sealed with nitrogen and have humidity-absorbing cartridges that can be replaced when saturated, according to Bouchut.
Waddell said Fujinon’s sports lenses not only have a compartment for desiccant drying packs, “but the way the lens is designed, whenever you go through focus and the focus elements move, it displaces the air in the lens.” He said a fogged lens can be quickly cleared by rolling through focus a few times.
Sports lenses may temporarily be parked at the limit of around 100-times, but if history is any indicator, that barrier will be broken. In the meantime, optical engineers at the three companies continue to try new glass, new coatings, new designs to increase optical quality and bring down the weight of existing zoom lenses, while keeping them rugged enough for even Americans to use.
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