One of the things I love about photography is the surprises I get when I upload images to my computer. I try to intentionally craft each photograph using lighting, composition, and patience. Even so, every now and then something surprising shows up when I look through the images. Sometimes it's a fleeting facial expression that got captured. Sometimes it's how the aperture combined with the compositional elements. Sometimes it's that the image turned out better than I was anticipating.
The picture above is an example of serendipity. This little girl didn't hold still for very long. I did not pose her in this position. Capturing a picture of her in the foreground, looking forward, with her parents blurred slightly in the background on each side of her was somewhat miraculous. :)
This picture is another example of serendipity. I was doing a late afternoon shoot with this mother and daughter. We had done a bunch of shots down in a valley and when we came back up (thinking we were done) the sun was just setting. I had not expected to get any backlit shots, but was happy with this one.
One last example comes from an indoor session. I was using my old camera on Live View, which involves the screen image blacking out for several milliseconds when taking the picture. I knew I hadn't gotten any genuine smiles yet, but when I uploaded this last image I found out that during those last black milliseconds a genuine smile had appeared and been captured.
I enjoy these moments of "engineered" serendipity.