The upcoming Canon 40mm f/2.8 has a designation of STM on the lens. What does this mean? What are the advantages of having it and does it replace an older technology? We have a terminology thread ...
In the Canon EF 25-105mm f/4 L USM IS lens specs, it says that the lens coating is "Super Spectra Coating". What is the Super Spectra Coating and how it differs from other types of coating?