The exposure triangle includes aperture, shutter speed & ISO. Another term for aperture is f-stop.
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What is f-stop?
The f-stop is in reference to the amount of light that you camera lets in. In fact, your f-stop is directly correlated to your lens and how wide your lens can go.
When talking about f-stop people will use the term – smaller f-stop. This means that the number is actually a higher number when you think of it mathematically. For example, f/14 is a smaller f-stop compared to f/1.8.
Another term is wide open. This means that your f-stop is as wide as it can go. That means that if you have a lens that can go to f/1.8 and you shoot at f/1.8 then you are shooting wide open.
If someone tells you to “stop down” on your aperture they are also referring to using a smaller f-stop (bigger mathematical number). It can be confusing but don’t let the terminology confuse you.
What does increasing the f-stop do?
When you increase the f-stop, meaning you are using a smaller number, then you are going to have more of your photo in focus. Remember the more wide open your aperture is the less of your photo is in focus. In addition to having more of your image in focus, you decrease the amount of light coming into your meter.
A wide aperture allows in a lot of light so the opposite happens with a smaller f-stop. To counter balance this you may need to decrease your shutter speed or increase your ISO to bring in more light.
Is f-stop and aperture the same thing?
Sort of. Photographers will sometimes interchange these terms however there is a slight difference. The aperture is the actual opening of the lens diaphragm. This affects how much light the lens lets in. However, the f-stop is the ratio of the focal length and the aperture diameter.
When to use a wide or smaller f-stop
Once most photographers figure out how wide of an f-stop they can shoot they love to shoot around f/1.8. This is because they think this is the only way to get the blurry background with bokeh they are looking for. However, that is not always the case.
In fact, I tell my students often to not shoot at f/1.8. Learning to use a variety of f-stops in your photography will help you create interesting images.
Below are seven reasons why you should rebel against a wider f-stop and shoot with a smaller f-stop.
1. Photographing a fast moving child or subject
We all love bokeh (you know, that blurry background) and using a wide aperture like f/1.8 is sure to help you get it. However, that wide aperture also makes your plane of focus smaller and makes it harder to get your focus just right.
When you’ve got a quick moving child, you need some wiggle room. You don’t need to go extreme with f/22 but consider closing up your aperture some to f/3.5 or so. This will still allow you to get some good bokeh.
2. Landscapes photography with a smaller f-stop
This world is beautiful and sometimes we want to see every detail we possibly can. When photographing landscapes, it’s common to shoot at a small aperture to get as much in focus as possible. I prefer around f/22 to be able to capture the clarity and details that surrounds me.
3. When photographing a group
Getting one person in focus at f/1.8 is hard enough but add in a few more people and it gets extra tough. How small your aperture needs to be is going to depend on how close you are to the group and whether they are on the same plane of focus or multiple ones.
For example, in the following image I am far away from them with a long lens. Since they are hugging, the focal plane for each child doesn’t differ too drastically and I can get away with an f/4 aperture.
However, being at f/4 with the below image wasn’t cutting it since I was so close to the group and there are 3 different focal planes. This is an instance where a smaller aperture of f/8 was needed to get everyone in focus.
4. Include a clear focus of the atmosphere
Sometimes your surroundings are important to the story of your photo. In the photo below, it was important to see both the definition of the clouds in the background as well as the elements in the foreground.
Perhaps you’re photographing a portrait of a bride and groom in front of the church they’re getting married in? The church is an important detail too.
5. Create a starburst effect
Starbursts have a knack for making bright items clean, shiny, and fancy. In order to get a good starburst, you need a small aperture. The smaller the better. If you don’t have enough natural light to embrace a small aperture you may need to consider including a secondary light source or a tripod to embrace a slower shutter speed. Starbursts are especially fun with the sun or Christmas lights.
6. The night’s sky
You really want a nice solid focus of the stars when photographing them. The best way to do that is to use a small aperture. You’re working with a slow shutter speed so you might as well slow it down a little more in order to use a smaller f-stop. Don’t forget that your best bet for astrophotography is when there’s a new moon and in a place with very little light pollution. If you have trouble keeping up with the moon phase, I’d suggest downloading the Star Walk app.
7. Macro photography
With macro photography, your depth of field is much more narrow than when taking a portrait. Because of that narrow depth of field, you need to use a smaller aperture in order to get more in focus. Being that close with a larger aperture can create a fun and pretty abstract sort of look but when you want all the details, think of using a smaller f-stop. The below photo was shot at f/8 and you can see how I got a good deal in focus but because I was so close, I still got some lovely bokeh.
Frequently asked questions about f-stop
The f-stop tells you what setting your aperture is set to. It is written as a fraction f/number. For example, it could be f/8 which reads as f-stop 8.
A higher number f-stop or often described as a narrow f-stop allows more of your photo to be in focus. As mentioned above there are a variety of times where you may choose to use a higher f-stop. However, a photo can be just as powerful with a wider f-stop (smaller number). It really depends on the look you are going for.
The lower your f-stop number the more light is coming in. For example f/1.8 will bring in more light than f/4. But it’s important that a wider f-stop will not only bring in more light but it also has less of the image in focus.
It really depends on the situation but I would say I often shoot at f/3.2. This allows in enough light for most situations plus it gives me wiggle wrong for nailing my focus when photographing my children. Keep in mind that you don’t have to shoot wide open at f/1.4 or f/1.8 just because your camera can. You can still get a blurry background that makes your subject pop at f/3.2.