Lens coatings

Lens coating technology is a subject that fuels animated discussions. Credible information about coatings is scarce, which is no surprise considering that data about a lens maker’s unique coating is a preciously guarded secret. One is, therefore, forced to rely on observation and experimentation.

Generally speaking, the practice of coating lenses, invented in Germany in the 1930s, became more common after WWII. Until the late 1950s most lenses appear to have been single-coated and this seems to have been the norm at a time when color film was a niche interest. As color film gained popularity during the 1960s, many lens makers began experimenting with multiple coatings. Coating in multiple layers seems to have truly taken off sometime in the second half of the 1960s. By then, interest in photography was becoming a mass consumer phenomenon and color film held the dominant position among both consumers and pros, while black and white photography had been relegated to the sidelines.

It is at approximately that time that many lens makers began using the expression "multi-coated" in reference to superior coatings formulated with color photography in mind. I suspect this term gave consumers the misleading impression that lenses made before "multi-coated" ones were, implicitly, "single-coated", whereas they may have had "only" 2 or 3 coatings, instead of 5, 6, or 7.

There is no agreement about when the first multi-coated Hexanons appeared. The often repeated view is that Hexanon lenses with the gold-amber colored coating (1965-67) are single coated and better adapted for back and white photography, while the ones with the later blue-purple Color Dynamic Coating (1968 on) are multi-coated and optimized for color film. Earlier Hexanons, however, often exhibit properties that are proper to multi-coated lenses. A closer examination of the coatings of many Hexanon lenses of the 1965-68 period (and even some of the F-mount era – 1960-65) reveals reflections of more than one color – a sure sign that more than one type of coating was applied, if not necessarily on the same glass surface.

With the introduction of Konica’s Color Dynamic Coating around 1968, Hexanons earned a reputation for beautiful color rendition, unique image vividness and very good flare control. It wasn’t long before Hexanons began to be referred to as the "slide shooter’s lenses". Konica’s Color Dynamic Coating was improved progressively throughout the seventies: This evolution can be observed in the performance of Konica’s 5 Hexanon UC lenses and in most other Konica lenses from the late seventies and early eighties, which show a even better control of flare than their counterparts from the early seventies.

The dominant hues of coatings on most Hexanon lenses are the following (the colors shown are an approximation):

1.         ████     Gray  (most F-mount lenses – 1960-1965),

2.         ████     Straw  (some F-mount telephoto lenses – 1960-1965),

3.         ████     Amber  (early AR-mount lenses – 1965-1968),

4.         ████     Purple  (Color Dynamic Coating – 1968-1988),

5.         ████     Green  (UC lenses – 1975-1981),

6.         ████     Pink  (some Tokina-built zooms – 1978-1988).