This Video of a Sigma Telephoto Lens Being Made is Weirdly Relaxing

If you’ve ever wondered why camera lenses are so expensive, you’ve come to the right place. Quality glass, particularly telephoto zooms, are hard on the wallet precisely because of the precision and care that goes into the manufacturing process.

This fascinating video shows the complete process of making a Sigma 70-200mm telephoto lens at the Sigma Aizu factory in Japan. Surprisingly, a lot of the work is still done manually or at least semi-manually. It’s also strangely relaxing to watch, almost like a ballet performance with intricate and perfect choreography.

How are Camera Lenses Made?

The journey begins with the rough grinding process, where raw glass material is shaped into the basic form of the lens. High-quality optical glass is the main raw material used in making camera lenses, and it is chosen for its clarity and ability to precisely refract light.

This glass is then polished to perfection, and technicians use specialized tools to check for imperfections by looking for Newton’s rings to make sure that the lens meets extremely high standards. The role of precision in camera lens manufacturing cannot be overstated, as even the slightest deviation can affect the image quality.

Lens Coatings to Enhance Image Quality

After polishing, the lens undergoes a visual inspection to detect scratches or dust, and any defects are addressed before moving to the coating process. The importance of the lens coating is evident here, as a thin layer of vaporized metal compound is applied at high temperatures to reduce glare, improve light transmission, and protect the lens from scratches and environmental damage.

Lens Bonding

Next, the lens bonding process combines concave and convex lenses to correct chromatic aberration, ensuring sharp, colour-accurate images. The lens is then treated with a black coating to prevent internal reflections and reduce light interference, further enhancing optical performance.

Once inspected, the lens is bonded to a plastic frame, known as a lens barrel, which is crafted through injection moulding using pellets melted at high temperatures. Metal components are precision-machined through cam processing and treated with chemicals to enhance corrosion resistance.

Final Assembly of the Lens

The lens undergoes painting and colour filling to make sure that the markings are clear. This is followed by assembling the parts, where all components are meticulously put together. Finally, the lens is subjected to rigorous tests for function, durability, and quality, including resolution checks using test charts. Then, it’s time for the finished lens to be packaged and shipped to photographers worldwide.

This detailed process shows just how much care goes into making a camera lens and proves Sigma’s commitment to excellence and innovation in optical engineering. Watch the video below; it’s quite incredible and will give you a new-found respect for your lenses!