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Zoom in on Zoom Lenses – The How and Why

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By: The Cooke Team  |   3 Lesezeit

An introduction to cine zoom lenses

The Zoom Lens – the lens that afforded filmmakers new techniques, the lens that revolutionised news gathering, the lens that can be just as good as a prime? Perhaps… let’s deep dive into the history of the zoom and how it has developed over the decades.

If you consult the trusted American Cinematographer Manual then ‘by definition a PROFESSIONAL zoom lens is a precision optical/mechanical system, which can change its field of view without noticeably changing its aperture or focus.’ In physical design this is made possible by the use of complex cams and followers which control precisely designed and manufactured optical components.

Zoom lenses are frequently more intricate in their design, as well as physically bulkier and weightier compared to prime lenses. The intricacy of their optics makes it challenging to produce a zoom lens without some compromise in image quality. Traditionally, it was commonly believed that zoom lenses fell short optically when compared to prime lenses. This was largely due to varying image aberrations across the zoom range.

However, in the realm of modern zoom lenses from reliable manufactures this is no longer the scenario. A well-crafted contemporary zoom lens such as the Cooke Varotal/i FF can match the performance of a prime lens. There will however be added size and weight. This is primarily attributed to factors such as the higher count of optical elements and more complex design considerations to achieve similar precision and aberration correction as an equivalent prime lens.

This being said, the gains from utilizing zoom lenses abound – you’re not limited to the set focal lengths of your prime lens set – if you’re in a location where the shooting space prohibits ideal camera placement then a zoom lens can get you much closer to the most suitable framing than a prime set could. If working on a remote head or crane there’s more options for flexibility without having to loose time changing lenses. Then there’s the creative possibilities; adding speed to action through zooming in, revealing the vastness of a space a character is inhabiting through zooming out. Giving the camera a “roaming” style perspective reminiscent of newsreel footage or even the ever popular Dolly Zoom effect. The increase in quality over the years has also led to the real possibility of using a zoom as a “variable prime” without compromise of clarity.

Cinema zoom lenses became popular in the 1960s and 70s. To begin with, zooming within a shot was frequently employed and some may feel it was overused which lead to a dated reputation. But like any technology, if used to support the story and emotions it can be an incredibly useful tool.

The range of a zoom can be very short while others may have a significantly longer range. A matched set of zooms ideally gives you a crossover between ranges for increased flexibility and usability. Zoom ranges can be noted by the specific range (such as 30-95mm) or by a ratio (such as 10:1) or a multiplier (10x), the longest focal length in both these cases being 10-times longer than the widest.

 

The History of 35mm Zooms – Back to 1932

The history of zoom lens technology is inherently linked to the Cooke brand. Arthur Warmisham was a pioneering optical engineer who joined Taylor, Taylor & Hobson out of school in 1912, becoming director of optical design and research ten years later. He oversaw the revolutionary Cooke Varo, released in 1932.

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Cooke Varo Zoom
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Arthur Warmisham

The Cooke Varo 40-120mm f/5.6 was the first non-telescopic complex zoom lens for 35mm motion picture photography. Although it represented a major advancement in zoom lenses it was essentially a bulky aluminium box. The lens came equipped with a special saddle that attached to a standard tripod plate. This saddle then held the lens and camera, ensuring correct alignment. As well as being bulky it had fixed focus – set at the hyperfocal distance of 150ft. Closer focusing then was achieve with screw on diopters allowing focusing from 30ft to 1ft as needed. Changing the aperture involved engaging a clutch-like mechanism with one knob whilst a second altered the iris – the focal length was changed by a rotating crank.

The Varo synched the iris to the zoom mechanism so that it varied constantly during zoom to maintain exposure. Whilst other zooms of the time operated around f/8 or f/11 the Varo gave a consistent f/5.6 across the whole range but also allowed for operation at f/4.5 from 40 to 85mm and even f/3.5 from 40 to 50mm. The lens was picked up by the Department of the Army Air Corps for aerial reconnaissance photography. Motion picture use included Love Me Tonight (1932, director Rouben Mamoulian, cinematographer Victor Milner ASC) and King Kong (1933)

 

 

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King Kong (1933)
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Above - Zoom shot from King Kong (1933), Below a still from King Kong. Cinematography by Edwin G. Linden ASC, J.O. Taylor ASC and Vernon L. Walker, ASC

By the early 1970s the aptly named Gordon Cook had designed the Taylor-Hobson Cooke Varotal 5:1 20-100mm T3.1 zoom, previewed at the 1970 Photokina trade show and released by Rank Precision industries the next year. It was the first zoom lens that was made with a sealed front focus unit and fixed front element that eliminated the risk of dirt and moisture being drawn into the lens and allowed for easy fitting of matte boxes and filter holders. This advanced technology achieved new standards in shadowed area definition, light transmission and durability, in addition to giving ghost and flare-free characteristics. The Varotal was the first 35mm cine zoom to feature internal-focusing and using Cooke’s proprietary Varomag “wide-band” anti-reflective coatings the lens achieved a transmission of 80% – very impressive for the time.

In production until the late 1980s the Varotal 20-100mm was a staple lens amongst the leading filmmakers of this time. Stanley Kubrick employed thirty six zoom shots in Barry Lyndon (1975, cinematographer John Alcott BSC) utilising the 20-100mm on this shoot. The most common type was the reverse zoom, beginning in a close up and then pulling back slowly to gradually reveal more and more context, ending sometimes in vast landscape shots. Visually this reduces the character’s significance as the shot develops.

 

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A Kubrick zoom, The Shining (1980, cinematographer John Alcott BSC)
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Barry Lyndon Reverse Zoom (1975, cinematographer John Alcott BSC)

Not a company to rest on its laurels Cooke (as Rank Taylor Hobson) released their next zoom in the summer of 1975 at the Film ’75 convention held in London’s Royal Lancaster Hotel. This was to be the Cine Varotal 25-250mm f/3.6 (T4). This lens would be updated several times in the future. Just three years later the record breaking-ly fast Super Cine Varotal was launched offering the same zoom range but with a maximum aperture of f/2.8 (T3.1) which would remain unmatched for years.

This lens was used on by cinematographer Geoffrey Unsworth BSC on Superman (1978, dir. Richard Donner). For lots of the flying work the actor Christopher Reeve would remain stationary against a large blue screen and zoom-ins and outs were employed to alter his size in frame within the shot, one composited photochemically this gave the effect of Reeve flying away or towards the background plates.

 

The Cine Varotal was updated to the MarkII version in 1983 which benefited from improved optical performance, rating the zoom at T3.9. The 10:1 design was revised for a final time in 1992, under the name Cinetal MarkIII, which rated the lens at T3.7.

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The 10:1 25-250mm designs over the years
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The 10:1 25-250mm designs over the years

Rounding out their zoom series over the years, Cooke released a Wide-Angle Varotal 14-70mm T3.1 in 1986. Created by using a specially-designed, front-positioned aspheric element on the 1971 20-100mm lens to create this wider version. 1988 saw the launch of the 18-100mm T3 Varotal at the Photokina convention in Cologne, Germany. This lens was colour matched with to be released Cinetal MarkIII zoom and Cooke S4 prime lens set. So this future proofing combined with a range and speed that allowed entire features to be shot on the one lens led to this zoom in particular becoming must have glass for many cinematographers over the years. It’s still a popular lens today paired with digital sensors for a more vintage look.

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Double Page Spread of the 14-70 Varotal
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Double Page Spreads of the 18-100 Varotal

And of Gordon Cook? Well in February 1989 he was informed that he’d be receiving the Gordon E. Sawyer Award from the Academy of Motion Picture Arts and Sciences. Given to “an individual in the motion picture industry whose technological contributions have brought credit to the industry”. Gordon spent a week exploring the California coastline with his wife Joan along with enjoying the Oscar buzz and reception.

 

 

Jumping back to 1981 an honorary mention must go to the Cooke Varopanchro. Released in 1981 the 20-60mm T3.1 zoom gave optical performance comparable to prime lenses of the age. It also became popular to rear-convert the lens to anamorphic, giving a 40-120mm T4.5 version. This was used extensively by cinematographer Alan Hume BSC on Return of the Jedi (1983, d. Richard Marquand)

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Star Wars: Return of the Jedi
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Star Wars: Return of the Jedi

Bringing us up to the present day when it comes to 35mm Zooms, Cooke released the CXX S4/i Zoom in 2004. The ‘CXX’ refers to the release of the lens during the company’s 120th year! Cutting exactly with the S4 primes and matching their speed this zoom featured nearly no breathing and minimal flare along with a close focus of just 18 inches.

Technicalities and Creative Elements of Zoom Lenses

Whilst “zooming”, ever-changing the field of view during shot, is still a popular technique, today the zoom lens is also used as a variable prime. When considering which zoom lens to employ you must consider the range and close focus. The latter of which can quite regularly be not so extreme as the prime lens equivalent. This being said modern zooms such as the Cooke Varotal/i FF alleviate some of these concerns.

When considering exposure you should be thinking in terms of photometric aperture (T-stops). Zooms are much more likely to suffer from a loss in light transmission within the larger number of optical elements that are encased inside them. Don’t just trust that a photographic zoom with a given f-stop value will give you this reliably throughout its range as a T-stop but instead lean towards manufactures that have the proven consistent exposure and focus found in cinema zoom lenses.

Zooming can be achieved electronically or manually with operators usually picking what feels best for the scene emotionally. A slow consistent zoom can have a foreboding effect whilst an ever-varying manual zoom can lead to a spontaneous style more synonymous with documentary. If wanting to zoom smoothly a favoured device is the Preston Cinema Systems Micro Force – with a fine setting speed control and the option to set in and out points of the zoom range along with dampening this is a very versatile piece of equipment. For smoother zooms (electronically or manually) a good tip is to zoom through your entire focal length range a couple of times before making a take in order to distribute the lubrication within the zoom cams and bearings.

Each camera movement should have a purpose. Simply having access to a zoom function doesn’t mean it should always be used. The technique of zooming in and out, often known as „tromboning,“ which originated from 8mm amateurs and became popular among professionals, should only be employed when it serves the production’s specific needs.

Another technique, known as „searching“ is borrowed from televised sports coverage like baseball. It starts with a wide-angle view of the scene and zooms in when there’s a significant play or action. Conversely, the zoom-out movement, often used in commercials and films, can create a powerful impact when executed correctly. This technique involves starting with a narrow field of view and then zooming out to reveal another element relevant to the story.

Creating intimacy with a moving subject can be achieved by matching the zoom rate to the subject’s movement towards or away from the camera. This method maintains the subject’s size while showcasing changing perspectives due to alterations in the subject-background relationship. The focal length of the lens dictates the angle of view, which determines the picture’s width and height.

Zoom lenses can also convey speed. A rapid zoom from a wide angle to a close-up shot of a fast-moving subject intensifies the subject’s motion. Proper zoom techniques can even make still objects appear to be in motion by altering image size, creating the illusion of movement within a sequence such as in the Superman example.

Historical Sidebar – 16mm Zooms

Up until this point we’ve been focusing on zooms for the 35mm format, however it’s interesting to touch on 16mm as well. From its early days the format was widely adopted for home movies, documentaries and later on news television work. Zoom lenses have been part of the language of this format since its earliest days; for the smaller crews the ability to adjust focal length instantly was crucial for capturing life unfolding naturally in front of the camera.

The smaller image circle of 16mm allowed the zoom lenses that were manufactured to in turn be more nimble and Cooke were at the forefront in this world also. Just before the resurgence of Super16 in 1975, Rank Taylor Hobson introduced the Varokinetal (CVK) 9-50mm T2.5 zoom for standard 16mm cameras. Unveiled at the British Kinematograph Film ’75 convention in London, it was hailed as „the world’s first 16mm motion picture zoom lens capable of achieving image quality, resolution, and contrast usually associated with 35mm lenses, but at a significantly reduced cost.“

In 1981/82 the design was updated to cover Super16 and the Cooke Varokinetal 10.4-52mm T2.8 was born. It was first used by Curtis Clark ASC for The Draughtsman’s Contract (1982, dir. Peter Greenaway). In 1983 the now very rare Cooke 3×10 (10-30mm, T1.5) was released. Manufactured by “downsizing” the Varopanchro 20-60mm T3.1 the lens was used in more modern times by Ed Lachman ASC on portions of Carol (2015, dir. Todd Haynes) which earnt him an Oscar nomination.

 

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16mm Zoom Brochures Varokinetal
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16mm Zoom Brochures Varopanchro

Use Study – The Dolly Zoom!

Filmmakers have always been innovative when it comes to finding new ways to use technologies. This was definitely the case with the dolly zoom or contra zoom. The aim of the now iconic technique is for the viewer to perceive a change in size of the background whilst the foreground remains consistent, this can be the background growing in size and detail and overwhelming the foreground or the foreground dominating it’s previous setting as the background becomes reduced.

The effect is carried out by “dollying”, or tracking, in whilst zooming out or the reverse; zooming in whilst dollying out. A simple idea in theory but a successful execution requires strong communication between the camera operator and dolly grip as well as a smooth reliable lens that doesn’t draw undue attention to the technique through the introduction of vignetting or other characteristics that don’t remain consistent throughout the shot.

Visionary Alfred Hitchcock first conceived of the shot whilst filming his 1940’s film Rebecca but he was unable fully achieve his vision. Clearly the shot stuck with him though as eighteen years later he achieved the shot for the film Vertigo. It is believed that Hitchcock instructed Paramount second-unit cameraman Irmin Roberts to assist him in creating a shot that put the viewer in mind of being in a drunk state post fainting at a party!

Used sparingly the technique can be incredibly effective in representing emotional or tonal shifts and showing to the audience that a major turning point in the story is taking place. It can also suggest a feeling of “falling-away-from-oneself” or to suggest that a character is undergoing a realization that causes them to reassess everything they had previously believed.

Notable examples include in Steven Spielberg’s Jaws (1975, cinematographer Bill Butler ASC) when protagonist Martin Brody realises there’s a shark near the beach – this is on the speedier end of the examples. Conversely over fifteen seconds in Martin Scorsese’s Goodfellas (1990, cinematographer Michael Ballhaus ASC) during a scene between Henry and Jimmy in a diner Henry’s paranoia grows. The camera tracks back whilst the lens zooms in, the background outside growing and literally closing in on the two characters inside.

 

The technique has even made its way across to animation, most notably in Pixar films Ratatouille (2007, director Brad Bird) and the Toy Story series where the freedom of computer animation allows for “impossible” shots such as tracking out far beyond where you’d be able to in live action film.

 

The Future of Zooms

It’s clear then that zoom lenses are a versatile tool that have aided the art of filmmaking creatively over the years as well as pushing the boundaries of what is possible on a technical and manufacturing level. Whilst previous concerns around image quality when compared to primes were valid, even with semi-modern high quality optics this is no longer an issue and with digital cameras continuing to perform better and better in low light situations the reduced T-stop a zoom usually offers compared to a prime is a lot more manageable as well.

With ever more demanding schedules and the requirement to shoot multiple cameras for more sequences than ever before the zoom is undoubtedly here to stay and is an essential part of a camera package on higher end films. On smaller productions the right zooms offer great flexibility and nimbleness to the filmmakers whilst still allowing the cinematographer to add character and expression to the images.

The zoom lens has sometimes gone under-appreciated but in a world of never-ending options of prime lens sets, zooms can offer the filmmaker a whole new world of techniques and creative opportunities instead of just offering another look.

With large format sensors becoming ever more prevalent Cooke have once again stepped up to the plate. The latest offering being the Varotal/i FF zoom lens series. Covering a focal length range of 19-215mm across three lenses, with incredibly useful overlaps, and matching the S7 and S8 primes the lenses are true Zoomable Primes with all the benefits of modern optic design including Cooke’s /i Technology and offering an almost total absence of breathing, chromatic aberration and distortion.

 

If you’d like to learn more about the history of lenses ‘The Cine Lens Manual’ is a great resource.  Cooke spoke with the authors Jay Holben and Christopher Probst, ASC, you can see those interviews here.