Why are Canon lenses white?

Why White?

Have you ever wondered why exactly your coveted Canon lenses are white?  Why has Canon chosen to go with a white (or, off-white) motif for some of their lenses?  I was thinking the same thing recently and with a little digging I have found some interesting results.

First of all, and most importantly, not all Canon lenses get the signature white lacquer.  Most of their lenses are, in fact, black.  To answer the question of “why white?” we must go back in time to 1969.


A Short History Lesson

In the 1960’s Canon began experimenting with ways to increase the quality of the optical performance of their lenses. Traditional glass elements suffer from something called chromatic aberration, whereby the lens is not able to bring all the different wavelengths of light into the same focus.  Canon found that fluorite doesn’t suffer as much from these problems, is significantly lighter, and could be a huge leap forward in lens technology.

Problem

Fluorite in nature grows in very small crystals and therefore isn’t suitable for use in photographic lenses.

Solution

Canon started growing their own.  Before long they had perfected the process of growing large enough crystals to use in photographic lenses, and invented new techniques to grind the fragile fluorite into viable lens elements.  This process takes an extremely long time compared to traditional glass elements, and as you can imagine, increases the costs dramatically. In 1969 Canon debuted their first lens with a fluorite element with the FL-F 300mm f/5.6.


So What?

Well, as it happens, fluorite is extremely fragile and is more susceptible to heat expansion than traditional glass elements. If the fluorite elements in a lens get too hot, there’s a good chance they could crack or shatter from their expansion. Canon needed a solution to help disperse or negate the heat occurrence if they were going to make larger and larger fluorite elements.  So in 1976 they debuted the FD 600mm f/4.5 and FD 800mm f/5.6 which came sporting the all new white paint job.

Since then, nearly every lens produced by Canon with large fluorite elements, has gotten the signature white treatment. The white surface reflects direct sunlight and helps the lens from overheating and having its internal fluorite elements compromised by heat expansion.

Okay, So Why Are Some Lenses Black?

The obvious answer is, because they lack a fluorite element.  But that’s not entirely true.  Even since the beginning of fluorite use, lenses with smaller elements don’t suffer from the heat expansion problem like their large cousins. There have been quite a few examples of lenses with fluorite elements that were offered in the traditional black.  In more recent history, both the EF50-200mm f/3.5-4.5L and EF100-300mm f/5.6L had fluorite elements but were painted black.  In any case the reasoning behind this might be that the elements in the lens might not benefit at all from the white outer surface because they’re smaller and wont expand as much.

More likely is that they don’t need to be painted white because Canon lenses don’t have a hard stop at infinity focus. Its called floating infinity. Meaning the infinity point of the lens will float around the marker based on the relative heat of the lens.  Canon describes this as a heat-related feature to allow for the expansion of the elements when shooting in warmer conditions.

Some have argued that with current technology and manufacturing techniques that you don’t actually need to have the white reflective surface to help reduce heat expansion.  Painting the giant lenses white might actually be an ingenious marketing strategy by Canon to differentiate them from the competition.

What About Nikon?

Nikon, for unclear reasons, does not paint their fluorite lenses white.  They do indeed use fluorite as lens elements, and fluorine as a lens coating.  But for mysterious reasons, all of their lenses remain black, with their signature matte finish. I can only guess that Nikon doesn’t paint lenses white because because they don’t actually need to.  Nikon lenses also have a floating infinity, which might explain how they deal with heat expansion.

However, they also have a range of lenses that use don’t use fluorite at all, and instead employ Extra-low Dispersion (ED) glass which they claim offers all of the benefits, but none of the drawbacks of fluorite.


Bonus Trivia

There are no Canons in space.

In 2004, according to a NASA subcontractor, when NASA was asked what camera systems astronauts used in space, their reply was Kodak and Nikon exclusively. When questioned further, NASA revealed that the fluorite elements used in Canon lenses were unsuitable for the rigors of space launch, and suffered fractures from the vibrations therein. They mentioned that the fragile fluorite elements completely disintegrated due to the vibrations during launch. The Extra-low Dispersion (ED) glass, which is a mainstay in many Nikkor lenses, doesn’t suffer from the fracturing problem like fluorite does.  And NASA it seems, is content to keep using Nikkor lenses without the troublesome fluorite elements.

Canon does not currently make a super-telephoto lens without fluorite elements. 

 

© Copyright 2009-2016 Aperture Academy