Mention should be made here of the misconception many photographers have regarding coatings and color correction. As I have stated in earlier articles, color correction has nothing to do with coatings. This is accomplished solely by the choice of suitable dispersions of the glass elements employed. While it is true that color work my be adversely effected by the use of uncoated lenses, this is entirely due to flair from the uncoated surfaces, not to the lack of color correction. In fact many photographers continue to use Dagor type lenses for color work, and find the flair levels to be acceptable.
Many photographers question the feasibility of having an older lens coated.
Indeed, many lenses were retro coated during the fifties and sixties by firms such as Burke and James and others. One aspect of the typical single layer coating is just how it is applied. When the first coatings were applied, they were simply vacuum deposited, and the mechanical strength of such a coating was only fair. It was soon discovered that by baking such a coating, the film became denser and tougher. When lenses were retro coated, baking was often impractical due to cemented surfaces in the lens which would melt and become separated.