Every so often Canon brings out something that's just plain weird (e.g. the Photura); somethingthat doesn't fit with anything else they are doing at the time, and the EXEE is a perfect example. In the late 60s Canon was building up its F-series cameras with a run up to its top-of-the-line professional F-1. Meanwhile it had the serious-amateur market with the FT and its less expensive little brother, the TL. They took standard FL lenses. It was the way things were going.
But Canon brought out the EXEE, which was a throwback to an earlier time. It was a solid body that looked like all the other Canon F bodies, but it had a half-lens permanently mounted onto it. The idea was that user would have three interchangable halfs that could be attached, offering a standard 50mm lens, a 35mm, a 95mm lens, or a 125mm lens.
This camera was also sold as the Bell & Howell Auto 35 Reflex. B&H had imported Canon cameras for most of the 1960s, but when they parted company, B&H got a couple of Canon cameras branded solely under the B&H name. The lenses, however, retained the Canon name and fit either camera.
One other camera takes this same lens system, the Canon EX Auto (I don't yet have one).
I recently found this in the "Behind the Scenes" column of Modern Photography magazine, April 1969, pp. 10, 14):
Canon's low-priced EE SLR
Why did Canon go to a leaf shutter interchangeable front lens component camera design for their new 35mm SLR (called the EXEE)? One possible reason was to create a fully automatic 35mm SLR with changeable focal lengths at a lower price than anyone else. All others at present are focal-plane shutter or behind-the-lens leaf shutter with full lens interchangeability. The Japanese Government has some rigid minimum price regulations on these but no regulations in interchangeable front component cameras. Canon hopes to sell the 35mm fully automatic behind-lens meter EX SLR in foreign markets (like the U.S.) for about $150, which is approximately 30% cheaper than comparable focal-plane shutter SLRs with the same lens speed (ƒ/1.8). The interchangeable components, designed to convert the normal lens to a 35mm, 95mm, or 135mm [sic] ƒ/3.5 lens, are expected to sell perhaps as low as $50 apiece overseas. Whether the low price will overcome the lack of more focal lengths or the limited shutter speeds (1/8 to 1/500 sec.) remains to be seen. Local Japanese experts feel that the interchangable front cell lens component feature may be more suitable for overseas than the Japanese home market.
The Canon is a swap-meet find, and I got two accessory lenses to go with it, and they're both the 125mm. I may have the 90mm but haven't been able to locate it. It's hard to find EXEE lenses sold separately from the camera body.
For more information: Canon Camera Museum
Camera manual: Orphan Cameras.com