Some people are happy to shoot with lenses and think only of the results, but it can also be fascinating to think about how such complex, precision pieces of engineering are made. Some insight is provided by Dave Etchells over at Imaging Resource, who has just posted a story about his visit to Sigma's factory in Aizu, Japan. Etchells follows the process from shaping the lens surfaces, to polishing, assembly and testing.

However, no matter how hard you try, you can't make every lens perfect - as Lensrentals Roger Cicala explains in his recent blog post. He looks at lens production from the perspective of manufacturability and engineering tolerances, and what's done to mitigate against the unavoidable inconsistencies they bring.

Lens polishing at Sigma's Aizu factory - photo from Imaging Resource

The two articles make an interesting pair - the efforts made to make a lens as 'perfect' as possible and the reasons why that'll always be just out of reach.