One of the most common question photography enthusiasts ask me is “What f-stop do you recommend to take better pictures?” To me that is like asking a chef which spice to use to make all food taste better. Cooking is about combining ingredients to make a unique dish, and photography is no different. Photography consists of different “ingredients” that result in an image that is either pleasing to the eye or not. Some of the things that make up a photograph are light, composition, focus, time, sensitivity and depth of field. Today I am going to discuss depth of field, and how you can use it to better capture your subject and convey the visual appeal you want to share with your viewer.
Depth of field is a fancy pants way of saying what is in focus. When that little green box highlights your kids face in the view finder or on your phone screen, you are focusing the light rays from that distance to land perfectly sharp on the image sensor. Objects closer and further from that focus distance will converge slightly in front of or behind the sensor, causing indiscriminate edges, or blur. Whoa, did I lose you? I am going to take a Nerd Alert Break: If you want to learn more of the physics behind this send me an email, or I recommend “Introduction to Light: The Physics of Light, Vision, and Color” by Gary Waldman
Now that I got that out of my system, I am going to get back to how all this affects your photography. I prefer visuals, so take a look at the sketch I made below.
I know what you’re thinking, if the aperture is getting smaller, then why is the number getting bigger? And why doesn’t the camera just have a dial for depth of field? Without boring you to death with the math behind this (again email me if you would like to know more), a simple way to remember this is to decide how many things you want in focus. Just the subject and the tent? Then try a low number like f/2. Do you want it all in focus; the bush, flowers, tent, subject, mountains, etc? Then try a large number like f/22. The more you want in focus, the larger the f-stop.
I took my camera to the Japanese Gardens in Seattle to try and show some quick examples of how the aperture contributes to the depth of field. Both columns of images have an increasing f-stop, which results in a greater depth of field. The difference between the left and right columns is the distance I was from the subject (pine needles) and the background. The closer you are to the subject diminishes your ability to stretch the depth of field to the background.
A Note on Phone Cameras: Most phone cameras have what is known as a fixed aperture, meaning you can’t change the size of the hole (f-stop). This has to do primarily with their compact nature. So if you can’t change the aperture, then how can you affect the depth of field? Look at the right column above, if you get closer to the imagtheyou depth of field will diminish. So the closer you get to the subject, the blurrier the background will be, and visa versa. That being said, newer phone cameras are trying to overcome this by adding “portrait mode”. Some obtain this by using software to identify the subject and blur the background (google pixel, older iPhones) and some have begun to add a second lens with a wider aperture (galaxy, newer iPhones) and then combining the images. Either relying on program modes, or moving your feet, you now have the ability to control the depth of field in your cell phone images.
So now that you know how to control the depth of field, it’s up to you to decide when to use a large depth of field (high f-stop) or a shallow depth of field (low f-stop) in order to make an artistic photograph. The general guidelines are that landscape photographers set it to the highest f-stop possible, whereas a portrait photographers set the f-stop as low as it goes. In my mind these are just generic guidelines, and maybe for you they will work, but I like to dig a little deeper (get it, depth of field, ha).
What is your subject and what are you trying to show? Is your subject part of a bigger landscape and you want it all contributing to tell the story? Do you want to draw your subject away from a distracting background? In the end it is up to you to decide what feelings you wish to illicit in the viewer.
Here are two examples of both ends of the spectrum. You also might find that somewhere at a middle aperture is best for your shot.
*You may have heard the word bokeh recently (pronounced like okay with emphasis on the o). This is a Japanese word referring to the quality of the blur created by a shallow depth of field. Points of light turn to discs of light, as shown in this image I took of the sparkling water at the gardens, where I intentionally made them out of focus, creating a bokeh effect. This can be rather pleasing in portrait photography with a crisp subject in focus among the soft light discs.
So, there you have it, the tools you need to know in order to start modifying the depth of field in your shots. My recommendation if you are new to this subject is to experiment. Start taking multiple pictures of the same subject at different aperture settings. Then review when you get back to see if you prefer a large or small depth of field!
I hope you found this helpful, please comment below if you have any questions, or if you want to suggest my next topic on photography.