FD Lens (Rear) Cap

I'm not old, but I feel old when I think about film cameras... I never really got into shooting with film. I got into photography with a Minolta DiMage 7, and I graduated into Canon EOS cameras. But I have in my possession an old Canon AE-1 SLR film camera, and two lenses; the Canon brand 50mm FD lens, and an accompanying 28-135mm Vivitar FD lens.


The 50mm lens was already on the camera, and I wanted to try out the Vivitar lens. But I could not, for the life of me, figure out how to remove the rear lens cap! It wasn't a simple twist and turn like Canon EOS lenses, or even the Canon brand 50mm FD lens... I was befuddled.

When I tried to remove the Vivitar's rear lens cap to change the lenses... I couldn't! I couldn't figure out for the life of me how to! I started searching forums, high and low to no avail. Finally I got so fed up, I simply entered "FD rear lens cap" into Google, and I was led to a little 'ol post from Yahoo questions...

On the Vivitar FD lens, the ring with the red dot on it rotates clockwise, independent of the rest of the lens! Simple solution for a silly design. Attaching it to the camera, it doesn't lock down like the Canon FD lens; it just tightens.

I guess FD mounts come in two flavors, breech lock and bayonet. User "cyanskylight" of YouTube demonstrates this in action.

Side note, I love the viewfinder split-prism focus screen (rangefinder and microprism ring). It makes manual focus a no brainer, and beats auto-focus into the ground. I wish modern SLR cameras had this.