Stopping (and starting) and Powers of Two
What is all this talk about stops and what power does it have? When you first enter the world of photography you have to reconcile yourself to this term of stops, at least I did. It was a confusing term at first. That and the idea of fast or slow. Eventually I suppose all of us grasp the meaning in whatever way we find useful. Photography expresses all aspects of an exposure whether on film or paper in f-stops. Though it did not always and even today not everyone everywhere expresses exposure as stops. The term derives from the settings on the aperture of a lens. That apparatus now almost exclusively defined as a movable diaphragm (though not always as some cameras use neutral density filters and some old cameras had plates with different sized holes drilled in them.). Indeed our current system was not so universal. I came across this when I obtained an old Kodak rectilinear lens and was confuse by the aperture markings. This article here explains in more detail this history. I f