We have explored ISO and the effect it has on exposure the last couple of weeks and next, we will consider another component of the exposure triangle in photography: aperture. The aperture is the opening in a lens, which can be adjusted to be larger, smaller or somewhere in between. The numbers representing this opening are called f-stops. The f/stop numbers have an inverse relation to the opening size: the smaller value of the number the larger the opening in the lens and more light is let in; conversely, the larger the numerical value the smaller the lens opening and less light is available.
When shooting at a wider opening or, a smaller numbered f-stop, the depth of field is also affected. With the lower f-stops or smaller numbers, you have a shallower depth of field; especially helpful when you want to isolate your subject from the background.
Here, using an f/5.6, the anemone is in focus but the top portion of the photo is beginning to blur.
A smaller f-stop can also be used when shooting landscapes and you want to bring attention to one element or person.
Since the ocean is on a very different plane than the cactus the ocean water details turn a velvety blue when using the f/5.6 setting in this photo.
For the egret in flight, a f/7.1 setting was used which results in most of the elements of the photo in focus.
When everything in sharp focus is the goal than an f-stop of 11 or higher should be used. For this landscape, I chose a setting of f/22.
If you would like to re-visit another backyard sisters post on depth of field and f/stops using a different subject click here.
Also, if you would like to learn more about exposure, there is an excellent book by Bryan Peterson titled Understanding Exposure, it gives an in-depth explanation of the different aspects of the exposure triangle accompanied by creative and colorful photos.
This week you will find me out looking for depth in my field,