May 27th, 2013 - 11:17 AM
F/stops what are they and what do they do anyway?
In the next couple of posts I am going to answer these questions and a couple of others regarding “The Mysterious F/Stop”.
What is the difference between an f/stop and an aperture? Well there is no difference, an aperture is an opening, hole, space, orifice, gap, or slit and so is an f/stop.
So where does the “f” in f/stop come from and why did they make it backwards, with large numbers to designate small openings and small numbers to designate large opening?
F/stops are a focal ratio to the diameter of the lens, yikes! In English it means that if you have a lens which measure 60mm and you set the opening to 30mm or half the size of the lens diameter, you have set the f/stop or aperture to f/2. So if you remove the “f” and replace it with a “1” you end up with a fraction: f/2 becomes 1/2 and f/4 becomes 1/4 and so on.
We all know that if we want to make an image brighter we use an f/stop with a bigger opening f/1.4 or f/2 and if we want to darken an image we use an f/stop with a smaller opening f/32 or f/22.
The full stop f/stops: f/32, f/22, f/16, f/11, f/8, f/5.6, f/4, f/2.8, f/2, f/1.4 allow twice as much light in as you progress from small openings to larger ones and Half as much when you progress from larger openings to smaller one. Each time you either double the value of the opening or cut it in half you have adjusted the opening by one f/stop.
What else do f/stops do for our images? They determine your depth of field or what is in focus. Stay tuned for the next episode of “The Mysterious F/Stop”.