He really started noticing the camera when he was about three. That is, he'd seen it before, but that's the age when he really started to understand what it meant, and that I was looking at him. I don't know that it was self-consciousness, exactly, though that came too, eventually. But sometimes he didn't want to play along, and so he began to hide himself. He would duck his head down, or sometimes simply close his eyes in protest. Back then, it came with a scowl.
That was when I started asking his permission to take the pictures.
Nowadays, he will agree or disagree to being in a picture. Sometimes he will come along grudgingly, sometimes with enthusiasm. Sometimes not at all. Just before I took this picture, I told him that the light was really nice, and asked him if he would sit up so I could take a picture. He said OK, and closed his eyes. I asked him if he was sure it was OK, and he patiently said yes, so I clicked the shutter.
Shortly afterwards, a mischievous grin stole across his face and he pulled his pants down, shoving his back side toward the lens. "Take a picture of that!" he shouted gleefully.
So I did.
He said it was his favorite picture ever.