Camera Basics: Depth of field
Hello friend, it's nice to have you back! I hope you're alright and staying safe.
Today we are learning the second part of how to use your camera in manual mode. If you missed the first part, you should check that out before you move on to this lesson. Here it is.
We only have three main components to learn: exposure, depth of field, and motion. You already learned exposure, and it was the hardest one. Also, the three settings you learned last time (ISO, shutter speed, and aperture) are the only ones you need to know to keep going. I told you it was easy.
Sooo, today's post will be a piece of cake for you. I promise!
Alright, let's talk about depth of field!
Depth of Field
What is it? It's the distance between the closest and the furthest objects in a picture that appear acceptably on focus.
If it did not make sense, do not worry, I got you.
Let's learn visually: what is different about these two images?
The difference is how in focus is the background, did you get it?
That is exactly what depth of field is!
When you have only the subject in focus, you have a shallow depth of field (like in the first image). However, when almost everything is in focus, you have a deep depth of field (as it's shown in the second image).
Of course, there is a wide range of possibilities in between. It's not either all or nothing. Let's talk about this in a moment.
First, let's bring back some terminology from last week's blog post: do you remember aperture? That's the main concept that will impact depth of field. Let's learn how.
Let's review a bit what we learnt. Aperture is the little F number you see on your monitor. It's equivalent to how open the lens is, with a small number equating to a wider aperture. The smaller the number is, the more light will come in, and vice versa.
Alright, that was a succinct summary. If this does not ring a bell, you should probably go back to it.
So, aperture is one of the main factors to control exposure in your images.
But how does it relate to depth of field?
Well, depth of field is, simply put, how many things are gonna be in focus in your image. It it's shallower, less things will be sharp. If it's deeper, more things will be on focus.
Depth of Field is directly controlled by how "open" your lens is (or.. by the aperture). In fact, the wider the aperture, the less things will be in focus, making the depth of field shallow. If this does not make sense, hang on.
Let's do another fun little experiment like last week, so that we can grasp this concept better. Make sure to have a table or an even surface in front of you.
Alright, put your wrists on the table, making a triangle with your fingers, by pointing them up and making your fingertips touch.
Now, keeping your hands on the table, try to make the base of the triangle as wide as possible, widening the distance between your palms. The triangle should almost be like an horizontal line, with the tip being very close to the table.
Then, do the opposite thing. Keeping your hands glued to the table, shift them to make the triangle as tall as possible, having the base being very thin.
Now gradually go back and forth between the short and thick triangle, and the tall and thin one, while paying attention to the tip of your fingers.
You must have noticed that the tip of the triangle will be very close to the table when your palms are very wide and further away when your hands are close together. Easy, right?
Well, your lens works in the same way. When it has a broad aperture, like when your palms were wide, the focus point is close to your camera. That means that everything behind that will be out of focus.
When it has small aperture, as when you made the tall triangle having your palms close together, your lens is able to focus far away. The focus point reaches a wider distance.
(These are really simplified explanations, but you get the idea)
When you have a wide aperture, with a lower F number, your depth of field is more shallow. The subjects close to you will be on focus, and everything behind that will be blurred. Like this:
When you have a smaller aperture, with a higher F number, your depth of field is deeper. Almost everything will be in focus. Like this:
Let's recap really quick:
- Lower F-number (like F1.8) is equal to a shallow depth of field and a wider aperture, meaning that only your focus point will be sharp, with everything else out of focus.
- Higher F-number (like F18) is equal to a deeper depth of field and a narrower aperture, meaning that almost everything in front of you will be on focus.
Everything in between follows the same rule. An aperture like F 1.8 will have a shallower depth of field than F4, which has a shallower depth of field than F10. You will need to practice on your own to find your sweet spots with your camera.
Another thing that slightly influences depth of field is which type of lens you use. If you're a beginner, you should first learn to master it with aperture, so let's not worry about this right now.
However, if you're really dying to know, the focal length of the lens determines the image magnification. The wider the lens, the shorter the focal length, meaning that the background will feel farther away. The longer or more zoomed in the camera lens, the less depth of field you capture, meaning that the subject and the background will feel more squished together. Let's keep it at that.
I will be back to dig deeper into that, I promise.
For now, this is all you need to know!
I hope that this was helpful, and let me know if you need me to further explain it in the comments!
Thank you for reading!