It’s often said that lenses will outlive cameras. This is accurate in virtually all circumstances. The advice to “invest in good glass” is something I’ve heard a lot. However, as manufacturers hinted to in the past, things change. Although the sentiment is accurate, not all camera lenses are composed entirely of glass. For many decades, top camera manufacturers have used plastic and plastic hybrid elements in both their consumer- and professional-grade lenses. Why is glass the most used material for lens elements? And at what point does a lens maker determine whether to include plastic or not?
Summary of Contents
‘Good Glass’: Is It Really Just Glass?
The Origins of Lenses
When Did Plastics Start to Be Found in Lenses?
Enhancements to Lens Production
Why Use Plastic Lenses in Most Smartphone Cameras?
Plastic vs. Glass
Camera lenses can’t only use plastic lens elements, can they?
Why Does Industry Prefer Glass?
Why Would You Use Plastic Lens Elements?
What Role Will Technology and Lens Manufacturing Play in the Future?
IS ‘GOOD GLASS’ JUST GLASS IN REALITY?
Most of the time, the main components of camera lenses are made of superior glass. Plastics may be molded over glass to create some of the inner, smaller lens elements, which are referred to as aspheric hybrid elements. For such lenses, an inner glass part is molded over with plastic. Plastic components make up the vast majority of smartphone camera lenses. These little plastic lenses, which can concentrate light on high-resolution sensors, are jammed into tenths of an inch. Such lenses can produce amazing photographs, so what’s preventing makers of contemporary DSLR and mirrorless lenses from doing the same?
EARLY LENSES’ HISTORY
Single element lenses weren’t discovered to be very useful in the early days of photography. They weren’t often used because of a number of optical issues including chromatic aberration. One of the pioneers in the development of achromatic lenses is regarded as Charles Chevalier. These were created for the daguerreotype cameras that Joseph Nicéphore Niépce and Louis Daguerre were developing at the time. Even more so than Joseph Petzval’s well-known portrait lenses, Chevalier’s lenses were regarded as being in great demand.
WHEN DID PLASTICS IN LENSES BEGIN TO BE USED?
In the early 1930s, Taylor Hobson of England became the first producer of telephoto lenses as ens manufacturing technology advanced quickly. In reality, Taylor Hobson was the parent firm of Cooke Optics, a well-known lens manufacturer. But on March 20, 1934, Peter Maurice Koch de Gooreynd and a guy by the name of Arthur William Kingston joined together to create the KGK Syndicate Ltd. First, they developed a Plexiglas-branded polymethyl methacrylate (PMMA) plastic optical lens from Rohm and Haas. To demonstrate how unlikely they were to break, Koch even performed a public demonstration of bouncing their lenses off a table.
Soon after, there was a rift between Kingston and Koch. Who among them invented the first plastic lens caused their partnership to break up. A few years later, Kingston founded the optics company Combined optics Industries Limited (COIL). Their area of expertise was the compression and injection molding of plastic optic components. With representatives in the UK, the USA, and China, COIL still exists today and portrays itself as a market leader in precise low-vision equipment.
ADVANCES IN THE MANUFACTURING OF LENSES
Around 1937, Dupont started offering industries access to Lucite, the company’s commercial form of acrylic. Soon after, PMMA and its variants were used often in the production of lenses. However, early plastic versions weren’t without flaws. Compared to their glass counterparts, they were more susceptible to scratches and discolouration.
In the year 1957, Kodak started employing mass-produced plastic aspheres in their viewfinder lenses. The 1959 Kodak Brownie 44a was the first commercially accessible camera with a plastic lens. Over the next ten years, Kodak manufactured almost 50 million Instamatic cameras with plastic lenses.
The quality of polymers used in optics increased along with their widespread use. The first hybrid aspheric zoom lens with glass components covered in resin was created by Tamron in 1993. This was their 28-200mm f/3.8-5.6 Nikon mount lens. Hank Nagashima, the company’s then-president of its American subsidiary, Tamron Industries, referred to it as “our first-ever and possibly the first like it in the world.” These resin coatings do away with the hours of polishing that are typically required to make each lens element. Additionally, it considerably lowers expenses.
WHY USE ONLY PLASTIC LENSES IN MOST SMARTPHONE CAMERAS?
High-end smartphones no longer have 12-megapixel resolution cameras, which were formerly common. The once-unimaginable 100-megapixel barrier has now been passed by smartphone cameras, with Samsung’s S20 Ultra’s main camera packing a staggering 108 megapixels. (The Mi 10i from Xiaomi has a same resolution.) Precision aspherical lenses constructed of optical glass are often needed to resolve such high-resolution sensors and provide clear pictures. For their lenses, at least, consumer and professional camera companies would do that. In order to fit smaller, thinner lenses into the smartphone’s limited inside area, manufacturers looked to plastic resources.
PLASTIC VS. GLASS
Complex forms may be readily created by injection molding plastic. This makes it far simpler to produce aspherical, ultra-thin plastic components than glass. Glass, however, outperforms plastic in several ways, including temperature stability, general strength, breaking resistance, and high refractive index. Nearly all seasoned photographers would agree that they wouldn’t settle for anything less than the best picture quality when choosing camera lenses. To make it, quality glass is needed. Although it doesn’t presently make up the bulk of most camera lenses, plastic is nevertheless present in some of them. Because there isn’t much room in smartphones for housing lenses, the only option is to use tiny plastic lenses.
Camera lenses can’t just use plastic lens components, right?
Would making your preferred telephoto lens entirely of plastic reduce its size and weight? For wildlife and sports photographers, it would be a present. The previous several decades have seen considerable advancements in plastic manufacturing because of the high demand for smartphone lenses.
WHY DO FABRICANTS CHOOSE GLASS?
Glass still has several advantages over plastic when it comes to creating lenses, however. It has a greater refractive index, stability at different temperatures, mechanical strength, and diversity. This explains why, despite the presence of certain plastic components, a DSLR or mirrorless camera lens does not primarily consist of plastic. They are not found in the lens’ front or back elements. You don’t want the first lens element that the light passes through or the final lens element that it passes through before it reaches the sensor to have a significant sensitivity to shape changes caused by humidity. These days, lenses’ front elements also contain a variety of coatings. Compared to plastic components, glass components may have a wider variety of coatings put to them. The high transition temperature of glass is to blame for this. Additionally, anti-reflection coatings on plastics tend to deteriorate more quickly than on glass.
This is also the reason why the majority of smartphone cameras cover the exterior plastic lens element with a protective layer of sapphire or gorilla glass. Additionally, glass lenses are far more robust. Furthermore, they do not readily develop strong static charges that draw dust. Last but not least, compared to their glass counterparts, plastic lenses just do not transmit light as well.
WHY AT ALL USE PLASTIC LENS ELEMENTS?
The characteristics of aspherical lens elements have a significant role in the utilization of glass. An aspherical lens does not by definition have a spherical form. Such a lens is mostly spherical, but its edges are bent in the opposite direction. Such components enable lenses to be used at wider aperture settings and significantly lessen the aberration that spherical lenses often exhibit. Plastic molding is a more efficient way for lens producers to create aspherical components. This contributes to a lens’s less weight. Aspherical components made of hybrid glass and plastic are often used by manufacturers to enhance the quality of the light they transmit. Nikon, for instance, offers two different aspherical lens types. The hybrid kind utilized in certain lens types is called PAG (Plastics on Aspherical Glass).
When it comes to professional photography, you have to spend more money to acquire precise results from your lenses since they are essential to your livelihood. Nearly many photographers would agree that sacrificing size and weight for excellent optical accuracy is a worthwhile trade-off.
WHAT TECHNOLOGY AND LENS MANUFACTURING CAN WE EXPECT IN THE FUTURE?
It all comes down to keeping the lenses small in a tiny gadget that spends a lot of time in your pocket when it comes to smartphones. Someday, we want to see professional cameras with a comparable level of mobility and comfort. One day, camera lenses may use some of the technological breakthroughs made in smartphone lenses. Using silicon nanostructure waveguides instead of smartphones’ plastic lenses is the goal of the Boston-based business Metalenz. They assert that one day, their technique will enable the direct attachment of lenses to sensors. If this technology can be applied to professional and small camera lenses, there may be a day when sports and wildlife photographers may carry their high-end equipment in their jacket pockets.
It seems that glass will continue to be the material of choice for lens elements since it is better at transmitting light to a sensor than plastic. But as technology advances, we could soon see all plastic lenses generating a picture quality that is at least on par with glass.