The change from FD to EX lenses was
not the first time that Canon changed its lens mount. The venerable Canon FD series of lenses got it's start,
way back in 1959, with the introduction of the Canon R series. Previous
Canon cameras, with interchangeable lenses, had used threaded lenses, which
screwed into a threaded mount on the camera. Predictably, these were known
as screw mount lenses. The screw mount lenses gave photographers a great
deal of flexibility, particularly when combined with the SLR type of camera.
The problem with the screw mount lens, was that the lens had to be turned,
and turned, and turned. This was not a problem back before lenses were
integrated with the camera metering system, but as soon as through the
lens, and then full aperture metering were introduced, a bit more was asked
of the new lenses.
The lens itself integrated with the camera body at four places. There was a stop down lever, which was tripped by the camera to close the diaphragm during the moment of exposure. There was the aperture indicator, which linked to the camera's meter, and indicated the aperture setting on the lens. Then there was the full aperture pin, which also linked to the camera's meter, and was used to set the full open aperture, for full aperture metering. This last pin, was what set the FD lenses apart from earlier versions. Without it, the camera metering system would have no way of knowing what the full aperture was, and would thus be unable to meter properly, except with the lens stopped down. All of these linkages are mechanical linkages, and there are no electrical linkages between the lens and the camera body. To the right of the photo of the camera body, can be seen the lever which links to the aperture indicator on the lens. At the bottom of the camera, just under the light box, is the lever that stops the lens down, by engaging the stop down lever on the lens. The corresponding controls on the lens itself, are labeled in the photo below.
There was quite the rivalry going on, between Canon and Nikon, as there still is. Both companies constantly harped on the superiority of their respective optics; but Canon also advocated the physical superiority of its mounting system. The competing Nikon system had the aperture indicating link on the upper outside of the lens. This exposed a thin and somewhat delicate metal sliver to the world, elements, dirt, and rough handling. It also made it possible for the link to be damaged while the lenses were carried or stored. Bumping or dropping a Nikon lens could damage the pin. The usual response from Nikon was that this was a non issue, and that the indexing pin was more than strong enough to stand up to "normal" use. However, it should be noted that Nikon did eventually introduce a new line of cameras and lenses which had no external indexing pin.
As far as optical quality went, the systems of both companies were so good, that there was probably little or no difference between them. It was a moot point anyway, for most photographers. Unless you were a professional, or were wealthy, you did not use company lenses. Most photographers would buy their cameras with a 50mm to 58mm normal lens, and then go to aftermarket companies for the rest of their lens system. So for most of us, our lenses used the Canon or Nikon mount; but were made by Tokina, Vivitar, Tamron, or perhaps Rokina. Though ti woudl make a purist cringe to hear it, these aftermarket lenses were not so inferior, if att all, to teh factory lenses. Of course this depended on the brand. I had very good results with Tokina lenses, but would not take a Rokina as a gift. In some cases, teh aftermarket companies actually pushed the factory to develop better lenses. Tokina introduced a series of very fast lenses, including a 200 mm F2 lens, and an 80 - 200 mm F2.8 zoom, which forced Canon to develop a series of fast lenses of its own.
Older FD lenses had a silver mounting ring. This was eventually changed to black, in order to match the rest of the lens, and to match the all black camera bodies which Canon introduced on most of its models in the eighties. Eventually an improved version was offered, which had a locking pin, and was a true bayonet mount. Many Canon owners did not consider this to be an improvement. In theory, the older style mount could be tightened up, to compensate for mount wear. In practice, your shutter, diaphragm and other moving parts would wear out long before the mount ever got loose.
An improved mount lens is shown next to an old style mount, in the photo to the left. There si really not much of a difference, in looks. The new style mount is on the 85mm lens, while the 80 - 200 mm zoom has the older style mount. For most users, the new style was slightly easier to mount. The new style mount also had a small lock. This was to prevent the lens from unscrewing itself, and to give the user a positive indication that the lens was completely mounted. This latch is shown in the photo below, of one of the improved mount lenses. In practice, the lenses never unscrewed themselves, or worked loose. With both types of lens mounting systems, a red dot on the lens mount was aligned with a red dot on the camera body, for mounting. On the older style lenses, attaching the lens would unlock the mounting ring, and would even set it to turning a bit, so that it would not fall off of the camera, before the mounting ring could be turned.
In 1987, Canon introduced its new EX autofocus lenses. The two lines coexisted for a time, but in 1992 canon production of FD lenses ceased. It is a shame, really, because these were and continue to be excellent lenses. They were replaced, by the new EX lenses, in order to provide autofocus capability to the new line of Canon cameras. I hate autofocus, and can not tell you how many pictures have been ruined, by the auto system selecting the wrong spot on which to focus. What with these cameras having no focusing aids in the viewfinder, and no easy way to manually focus, the mistake is often not noticed until too late.
The new EX lenses are completely electronic, and have no mechanical linkages to the camera body. This is just the opposite approach to that taken by the FD series of lenses. This would make it impossible to design an all mechanical camera, using this lens mount. So, for better or worse, modern photographers are shackled to their batteries.
The old FD mounting system, and the great series of true photographers cameras, which was built around them, will be mourned by most traditional photographers. The one upside to their replacement is that you can get these truly great lenses at bargain basement prices. Of course, they can only be used with the older style F and A series cameras, and there are no digital models available for this mounting system. For a time, a company called Siliconfilm was offering a digital back for a standard 35mm camera. Sadly, they took too long, and the development of the digital SLR, by several mainstream camera companies passed them by. To bad really, because I would love a digital version of the old F-1, or FTb. These cameras used the most complex and capable computing system ever designed, to set exposure and focus - the human brain. Though a bit more effort was required, the results could be far better than today's 8 bit wonders.