Canon Just Came Up With a Weird Idea for Lighter Lenses

Canon is looking into resin (plastic) lens elements as a way to make professional camera lenses lighter, according to a newly uncovered patent. The patent outlines designs for zoom lenses that use plastic optical elements to cut down on weight, potentially revolutionizing the build of heavy telephoto lenses.

Patent Reveals Resin Optics in Zoom Lens Design

The Japanese patent application specifically describes several zoom lens formulas (examples include a 28-105mm f/4 and a 24-35mm f/2) where some lens elements are made of resin rather than traditional glass​. In the patent text, Canon notes the key motivation: using resin elements can significantly reduce the weight of a lens​.

Large-aperture zoom lenses typically require many glass elements, which makes them heavy. By swapping some for plastic, the overall lens could be much lighter and more compact. This approach might enable, for instance, a big 70-200mm or 300mm prime to shed a noticeable amount of weight – a change that busy pros would certainly welcome during long shoots. The idea isn’t entirely new; some consumer-grade lenses and compact cameras have used plastic optics in the past to save cost or weight. But it’s rare in high-end professional lenses because of performance trade-offs.

Overcoming the Challenges of Plastic Elements

Canon’s patent acknowledges the well-known downsides of plastic elements. Resin lenses are sensitive to temperature and humidity, which can cause them to expand, contract, or even slightly deform, leading to focus shifts or increased optical aberrations​. In other words, a lens that works fine on a cool dry day might lose sharpness in hot or humid conditions if the plastic element changes shape. Nonetheless, Canon appears to be continuing down this path of research to make plastic viable for serious use.

According to the patent, Canon’s engineers propose novel methods to stabilize the performance of resin lenses despite environmental changes. One approach focuses on using high-dispersion plastic materials that are less prone to expansion from moisture. Another is an optical configuration trick: for example, placing a plastic element in a group with both positive and negative power lenses to balance out any focus changes if the plastic element swells or shrinks​. Essentially, if the plastic element’s focal length shifts, another element in the group counter-shifts to compensate. The patent describes designs aimed at keeping the lens’s focus constant across a range of temperatures.

The patent specifically mentions addressing moisture absorption. Plastic can absorb water from the air over time, which not only changes its shape slightly but can even alter its refractive index (how it bends light). Canon’s documents suggest strategies like special coatings or sandwiching the resin element between glass elements to isolate it from the environment. The goal is a “lightweight, small-sized zoom lens that retains consistent optical quality despite environmental changes.”

Implications for Photographers

For photographers, the prospect of lighter telephoto or zoom lenses is exciting. Take Canon’s popular 70-200mm f/2.8 lens, for example – a staple for sports and wildlife shooters but a beast to carry all day. A lighter version with the same optical quality would be a relief (literally). Wedding and event photographers, who often lug around multiple heavy lenses, would also benefit. If Canon extends this tech to super-telephoto primes (300mm, 400mm, etc.), it could drastically reduce fatigue for those on safari or shooting field sports.

That said, it’s important to note this is just a patent at this stage. Camera companies patent many ideas that never become commercial products. Canon is likely experimenting and prototyping to see if resin elements can truly match the performance of all-glass designs in the real world. Image quality remains paramount – no one will accept a lighter lens if it produces soft or distorted images. Canon will have to ensure that aberrations, whether the light passes through plastic or glass. Moreover, professionals might worry about long-term durability: will plastic elements cloud, yellow, or scratch more easily over years of heavy use? These are questions Canon would need to address before any RF L lens with plastic hits the market.

The patent, however, shows Canon’s intent to innovate. In an era where mirrorless cameras are shrinking camera bodies, lens size and weight have become the next frontier. Other brands have tackled weight with methods like diffractive optics or fluorite glass to reduce element count. Canon’s potential solution: use a different material altogether. If successful, resin-infused lenses could maintain top-notch performance while being significantly lighter – a true win-win for photographers. While we might not see a plastic-element lens on the shelf this year, don’t be surprised if in a few years, Canon announces an ultralight professional lens, proudly touting some advanced polymer optical elements. It would be a tangible result of this research, and a hint that the venerable lens-making process can still evolve in the quest for portability.