Every DP is aware that the iris in a lens controls exposure and, as a side effect, depth of field. But here are five things which aren’t so commonly known about it.
Inside a lens, amongst the various glass elements, is an ingenious mechanism which we call the iris because it is modelled on that part of the human eye. It’s a critical part of exposure because, just like your biological iris, it controls the amount of light passing through the pupil to form an image. It also affects a number of other aspects of the picture.
