By Nila Kartika Wati 
Canon has filed a patent for a groundbreaking 70-135mm f/2 zoom lens designed for full-frame mirrorless cameras, signaling a direct strategic response to the Sony FE 50-150mm f/2 GM that entered the market last year. This ambitious optical design features an internal-zoom mechanism with a fixed front group, positioning it as a significant potential competitor in the rapidly evolving landscape of high-performance professional optics. The numerical examples detailed in the patent filing, specifically JP 2026-144169 as reported by Canon Rumors, indicate a focal range from 72.10mm to 136.89mm with an aperture of f/2.05, and an optical length of 211mm from the front element to the sensor plane. These specifications place the potential Canon offering firmly in the same physical and performance class as Sony’s pioneering telephoto f/2 zoom.
The New Frontier of Fast Telephoto Zooms
The patent application, while containing several optical examples including designs for a 200-400mm f/4 and a 180-600mm f/6.3 lens, places particular emphasis on the f/2 zoom. This focus underscores Canon’s apparent intent to push the boundaries of what is optically achievable in a telephoto zoom. A lens spanning the short telephoto range up to 135mm at a constant f/2 aperture would uniquely cover classic portrait focal lengths such as 85mm, 105mm, and 135mm, offering a full stop wider aperture than even the fastest 70-200mm f/2.8 professional zooms. This provides a distinct advantage in terms of light gathering and depth-of-field control, an appeal that Sony has already successfully demonstrated with its 50-150mm f/2 GM since its release in June 2025.
The technical specifics outlined in the patent reveal an intricate design, characteristic of Canon’s L-series professional lenses. An internal zoom design means the lens length does not change when zooming, which contributes to better balance, improved weather sealing, and a more robust build quality. A fixed front group further aids in maintaining consistent optical performance and allows for easier use of large-diameter filters without requiring mechanical compensation during zoom operations. Such design choices are critical for lenses targeting demanding professional applications where reliability and optical precision are paramount.
A Race to Redefine Professional Optics
The development of a 70-135mm f/2 zoom lens by Canon is not merely an isolated technical endeavor but a pivotal move in an ongoing strategic competition to dominate the high-end mirrorless lens market. Canon, in fact, initiated this race for ultra-fast zoom lenses. In 2018, with the introduction of its inaugural full-frame mirrorless camera, the EOS R, Canon unveiled the RF 28-70mm f/2L USM. This lens was revolutionary, challenging the long-held industry belief that a full-frame f/2 zoom was impractical or economically unviable to produce. Weighing in at 1,430 grams and requiring 95mm filters, it was a substantial piece of glass but delivered unparalleled performance, quickly becoming a flagship optic for the RF system.
For six years, the Canon RF 28-70mm f/2L USM remained unchallenged in its specific niche. Sony, however, mounted a formidable response. In November 2024, Sony launched its FE 28-70mm f/2 GM, directly targeting Canon’s standard f/2 zoom. Sony’s offering, at 918 grams and priced at $2,899.99, presented a compelling alternative, notably lighter than its Canon counterpart. Building on this momentum, Sony further pushed the envelope in April 2025 with the release of the FE 50-150mm f/2 GM. This lens, an internal zoom design weighing 1,340 grams, also utilizing 95mm filters, and measuring 200mm in length, priced at $3,899, created a new segment: the fast telephoto zoom. This move left Canon with an f/2 standard zoom but no direct telephoto equivalent, creating a strategic gap in its professional lineup. The current patent filing is the first concrete public indication that Canon intends to address this gap and reassert its leadership in this high-performance category.
Engineering Marvels: Deconstructing the f/2 Telephoto Challenge
The engineering required to achieve a constant f/2 aperture across a telephoto zoom range is immensely complex, though the physics behind it might be "less absurd than it sounds," as the original analysis correctly points out. The primary optical challenge for a lens designer is the entrance pupil, which dictates the effective aperture size. This is calculated by dividing the focal length by the f-number. For a 135mm lens at f/2, the entrance pupil is 67.5mm. In comparison, a 70-200mm f/2.8 lens requires an entrance pupil of approximately 71.4mm at its long end (200mm / 2.8). This calculation illustrates that the front optic of an f/2 telephoto zoom does not necessarily have to be astronomically larger than an f/2.8 zoom at its longest end.
However, the real difficulty lies not in the front element’s diameter but in the subsequent optical groups, particularly the rear elements and the vast amount of glass required throughout the lens barrel to maintain that wide aperture across the entire zoom range. Achieving a constant f/2 aperture at the wide end (70mm) demands significantly large rear groups to capture and funnel sufficient light. This necessitates a sophisticated optical formula, often incorporating numerous exotic glass elements such as aspherical lenses to correct for spherical aberrations, ultra-low dispersion (UD) or super UD glass to combat chromatic aberrations, and fluorite elements to minimize secondary spectrum errors and reduce overall weight. The density and arrangement of these elements contribute substantially to the lens’s physical dimensions and weight. This explains why Canon’s 28-70mm f/2, despite stopping at 70mm, weighs a considerable amount, and why Sony’s 50-150mm, covering a shorter telephoto range than a typical 70-200mm, weighs almost as much as its f/2.8 counterparts. The internal zoom mechanism, while offering structural benefits, also adds to the complexity and glass count compared to external zoom designs.
The Practical Advantage: Why f/2 Matters
For professional photographers, particularly those in wedding, portrait, and event photography, the practical advantages of an f/2 telephoto zoom are significant and tangible. The primary benefit is the extra stop of light gathering capacity compared to an f/2.8 lens. This allows for shooting in lower light conditions with a lower ISO setting, thereby preserving image quality and reducing noise.
More critically, an f/2 aperture provides superior depth-of-field (DoF) control and background separation. Consider a subject positioned 3 meters away: a 135mm lens at f/2 yields approximately 6 centimeters of depth of field, creating an incredibly shallow plane of focus that isolates the subject beautifully. The same lens at f/2.8, while still shallow, would produce about 8 centimeters of DoF. This difference of 2 centimeters might seem minor numerically but translates into a visibly more pronounced background blur and subject separation, often referred to as "bokeh." This aesthetic quality is highly prized in portraiture, allowing photographers to create images with a distinct, dreamy quality that draws the viewer’s eye directly to the subject.
Furthermore, such a lens offers unprecedented versatility. Many wedding and portrait photographers currently carry multiple fast prime lenses to achieve these looks—for instance, an 85mm f/1.4 or f/1.2 for classic portraits and a 135mm f/1.8 or f/2 for tighter headshots and environmental portraits. A single 70-135mm f/2 zoom lens could potentially replace these multiple primes, streamlining a photographer’s kit, reducing weight, minimizing lens changes during a shoot, and allowing for faster adaptation to changing scenes and compositions. This efficiency can be a game-changer in fast-paced professional environments. The robust sales of Sony’s 50-150mm f/2 GM have already provided strong market validation for this concept, demonstrating a clear demand for such high-performance, versatile optics.
Historical Precedents and Evolving Technology
While full-frame f/2 telephoto zooms are a relatively recent phenomenon, the concept of fast telephoto zooms has a longer history on smaller sensor formats, where the optical challenges are somewhat less daunting due to the smaller image circle requirements. A notable early example is the Olympus Zuiko Digital ED 35-100mm f/2, launched in 2005 for the Four Thirds system. This lens, weighing 1,650 grams, offered a field of view equivalent to a 70-200mm lens on a full-frame camera, but with a depth of field equivalent to an f/4 lens on full-frame. This demonstrated the feasibility and appeal of such fast zooms within the constraints of smaller sensor formats.
More recently, in 2016, Sigma pushed the boundaries even further with its 50-100mm f/1.8 Art zoom, designed exclusively for APS-C sensors. This lens provided an aperture a third of a stop faster than f/2, achieving truly exceptional low-light performance and shallow depth of field for its format. These historical examples illustrate a continuous industry drive to achieve faster apertures in zoom lenses, with advancements in optical design, glass manufacturing, and computational modeling gradually enabling these achievements on larger, more demanding full-frame sensors. The transition to mirrorless systems, with their shorter flange distances, has further opened up new possibilities for lens designers, allowing for more compact and often faster optical formulas.
Strategic Implications and Market Dynamics
Canon’s patent filing for an RF 70-135mm f/2 lens carries significant strategic implications for the competitive landscape of the full-frame mirrorless market. If brought to production, this lens would not only fill a critical gap in Canon’s professional RF lineup but also intensify the direct rivalry with Sony, particularly in the high-profit, high-performance lens segment. It would allow Canon to offer a complementary telephoto f/2 zoom alongside its existing RF 28-70mm f/2L, potentially forming a powerful "f/2 trinity" if a wide-angle f/2 zoom (e.g., a 14-24mm f/2) were to materialize. This would provide Canon professionals with an unmatched set of fast zoom options, covering a vast range of focal lengths with consistent f/2 apertures.
Industry observers suggest that this move is indicative of Canon’s long-term strategy to leverage its optical engineering prowess and intellectual property to differentiate its mirrorless ecosystem. By offering unique, class-leading lenses, Canon aims to attract and retain professional photographers who prioritize absolute optical performance and creative flexibility. The success of Sony’s 50-150mm f/2 GM has already validated the market demand for such lenses, setting a clear benchmark for Canon to meet or exceed in terms of optical quality, build, and features.
From Patent to Product: The Road Ahead
It is crucial to remember that patents represent intellectual property and research and development efforts; they do not automatically guarantee commercial products. Canon, like all major camera manufacturers, files numerous optical designs, and only a fraction of these ultimately make it to market. For instance, a patent for a 24mm f/0.7 lens surfaced last year but has not yet materialized into a product. Therefore, while this 70-135mm f/2 patent is a strong indicator of Canon’s intentions and capabilities, its eventual release remains speculative.
However, several factors lend credence to the possibility of this lens reaching production. Canon Rumors notes that Canon has one more major announcement day scheduled before the end of 2026, with new lenses expected to round out the year. The surfacing of two f/2 zoom designs in recent filings (the 70-135mm and another potential f/2 zoom) suggests a concerted effort in this specific optical segment. If a 70-135mm f/2 lens is indeed among the forthcoming announcements, it will undoubtedly be priced competitively against Sony’s $3,899 FE 50-150mm f/2 GM and weighed against its 1,340-gram mass. These figures now represent the performance and value benchmarks that any Canon f/2 telephoto zoom must contend with in the professional market.
The Broader Vision: Canon’s Future in High-Performance Optics
This patent filing underscores Canon’s ongoing commitment to innovation in high-performance optics and its strategic vision for the RF mirrorless system. By investing heavily in R&D for such complex and demanding lenses, Canon aims to solidify its position as a leader in photographic technology. The potential introduction of an RF 70-135mm f/2L USM lens would not only enhance Canon’s professional offerings but also signal a broader industry trend towards pushing the boundaries of what is possible with mirrorless lens design. This relentless pursuit of optical excellence ultimately benefits photographers, providing them with more powerful tools to realize their creative visions and further blurring the lines between what was once achievable only with prime lenses and the versatility offered by zooms. The coming years will undoubtedly reveal whether this patent translates into another groundbreaking lens that reshapes the professional photography landscape.
