Fran Scott learns how glass is made in a factory. The raw materials are described, together with the use of soda ash to lower the melting point, making it easier to form into useful shapes.

This relaxing video provides a behind-the-scenes look at Sigma's factory in Japan, showing the full assembly process of its 70-200mm lens.

He created a blue ceramic material, which was glazed. The lens was attached and run through a kiln to fuse the glass and ceramic together, leaving a round aperture of 4 millimeters through which ...