When you first begin learning about shooting in manual mode, you may wonder what difference your F-Stop (aperture) will have on your final image. In order to fully understand which F-Stop you should be using, you must first understand exactly what an F-Stop is, and how it changes your image.
What is F-Stop / Aperture?
Your aperture, or f-stop, is the opening in your lens through which light travels. When you look at your lens straight on, you'll notice a difference in the circumference of the lens opening when changing your f-stop from f/2.8 to f/22. You may have seen images, similar to the one above, that illustrate what different f-stops look like.
Understanding Light and F-Stop
First and foremost, your f-stop is one of three settings that affect your overall exposure of your image (with shutter speed and ISO/Film Speed being the other two). The main thing to keep in mind when choosing your aperture is this:
Larger Number = Smaller Hole = Less Light
For example, if you choose an aperture of F/2.0, you'll be letting in a substantial amount of light, especially compared to an aperture of F/16. When choosing an f-stop that is very low (like F/2.0), you'll need to choose a shutter speed and ISO that will compensate for how much light you're letting in.
When shooting outdoors on a sunny day, I typically shoot at a shutter speed of 1/1000th or faster, and an ISO of around 200 when shooting digitally. Aside from determining how much light is let into your camera, the f-stop primarily affects the depth of field of your final image.
Depth of Field
Have you ever wondered how to get your photo perfectly blurred in the background, while highlighting your perfectly in-focus subject? Understanding which f-stop to choose will allow you to decide how much of your subject you want in focus, or how much the background will be "blurred out".
The most important thing to note is this:
Lower Number = Shallow Depth of Field = Less in Focus
For most of my imagery, I shoot around F/2.0 - F/5.6. Shooting around F/2.8 allows my subject to be in focus, while making the background a bit more blurred. The image above is an example of what it looks like to shoot at F/2.0. You'll notice there's a focus on the flowers the bride is holding, while the rest of the image slowly fades into a blur. If I had wanted to get the entire groom and bride in focus, I would have shot around F/2.8 - F/4.0.
Additionally, creating this 'blur' in the background will be much more noticeable if you have some sort of light source behind your subject. For example, if you have string lights hanging behind your subject like the image below, you'll notice that shooting at a lower f-stop will create a bokeh that can be beautiful.
So which f-stop should you be using? There is not one correct answer for this, and it will heavily depend on your style of work, but a good rule is this:
Portraits Focusing on People | F/1.8-F/4.0
Detail Flat Lay Images | F/4.0-F8
Large Group Portraits | F/4.0-11
Stay tuned for future posts on specifically when I choose certain f-stops over others.
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