Yes, I realized that after I looked it up, that Canon did not make a FD 58mm lens. But my FL 55mm f-1.2 does have that stop-down feature.
I am going to upload a photo from a bicycle ride I took a few weeks back. I took along my Canon T-90, with my FD 70-210mm F-4 lens on it. It's not a top-of-the-line lens, but it's the one I've got. While on the bicyle trail, I found what at first I thought was a very large dog, only to look closer and see it was a very small pony, a Shetland pony that had gotten out of the home's yard and was loose on the open area beneath the powerlines where the bicycle trail also went through. It was a grassy park. The owner, a woman had "lost" two ponies, and had taken the one by the bridle into the yard, and was calling the other. It started running, and I got this shot of it on the move. Shutter speed, I think, was 125th second, and the lens was wide open at F-4. The film was Kodak 100TMAX.
John