A tenth of a second is all it takes - yes, the blink is a marvel of human physiology that clears dust away from the eye and helps lubricate the eyeball. We have learned to cope with momentary blackout by suppressing those parts of the brain that monitor visual change, in a manner similar to the way we are able to ignore our blindspot caused by the optic nerve entering the eye. So why the hell do I often end up photographing people with their eyes closed?!
We blink around fifteen times every minute and they only last for a tenth of a second. So out of a full minute of vision, only one and a half seconds is taking up with blinking. That can go up when we are stressed (which can often happen when people don't like being photographed!) or thinking about something else, and can go down when we are relaxed or intently engrossed. The odds of photographing a blink seem stacked against us - it seems incongruous that not only do we tend not to notice ourselves blinking, but often don't see others blink. Film editors are supposedly known to edit out blinks to stop the distraction - that said, when people are in conversation, they often don't blink until they have finished their dialogue.
So I say, damn blinks - they create a nigh-on useless photo and occur far more often than the 40:1 ratio suggests. Just look through your own back-catalog to see how many you have. Of course, there are situations which are understandable: bright light is a classic example where people squint and then blink. It's not particularly photogenic, so either get your subject to wear sunglasses or just close their eyes whilst you count to three, then open them. Sneezing is another unedifying pose to be caught in, although you're best just letting it out!
However, it is problematic for the "normal" blink - the variety that everyone does every minute of every day. How is it that I manage to pick the moment they involuntarily choose to blink? Of course, there are ways around this when taking a portrait. One of my favorite methods for a more intimate moment with my client is to ask them to close their eyes and then indulge themselves by immersing their mind in a happy event they experienced. I count down and, when they open their eyes, capture what can be an electrifying moment of emotion. When you are posing some individuals they naturally open their eyes at the moment you capture the image - it's normal to present yourself, eyes open, for a portrait. Or for individuals or groups, engage them in conversation. When they are intently talking to you, it will be eyes open.
Candid shots are a different beast. The blink doesn't seem to be an ephemeral affectation, rather a common feature. For me, they seem to happen time after time - maybe my timing is off, maybe I don't see them blink. Maybe it's something else and, lost in the photographer's mental dance of trying to guesstimate Bresson's decisive moment, the blink is there, ready to scupper my well-intentioned plans for that intimate moment. All pretense of creating a stark manifestation of Berger's quotation lost in that indecisive moment. Did Berger (or Mohr) and Bresson suffer from this fate? Does anyone else have problems with blinking or is it my own affliction to continue capturing people, sightlessly staring at the camera? If you've got any classic blinks, then do post them!