What is F Stop - A Guide to Understand It
What is F Stop!
This will be in your mind, or you might know the answer and want to learn more about it.
Photography professionals know an f-stop is just one aspect of a camera’s output.
F stop is a measure of how large your aperture opening will be in relation to your focal length.
As an example, if you have a 50mm lens and an aperture of 2.8, then this would mean that your f-stop is 2.8/50=5.6
The article goes on to discuss the different types of lenses – prime or zoom – as well as what camera settings are best for shooting at night time with no street lights.
What Is F Stop
In f-stops, “f” stands for the focal length of the lens.
The focal length of a lens refers to its field of view, while the f-stop refers to light you allow to hit the sensor via the aperture opening.
Your exposure is determined by how much light gets through the aperture and thus how bright it is.
(Focal-STOP) The f-stop is the opening of the camera lens that allows light to enter.
Additionally, it specifies how much of the subject is in focus in front of and behind the subject (the depth of field).
The f-stop of a camera lens is one of the most important measurements. This will show you how your maximum aperture changes as you zoom.
Why Does It Matter
The aperture opening is what determines the depth of field, which is how much of the scene in front and behind your subject will be in focus.
In aperture priority mode, your camera will automatically adjust the shutter speed as you do this to maintain a balanced exposure at all times.
You can adjust the shutter speed of your camera and keep the exposure constant between frames by shooting in aperture priority mode.
A shallow depth of field of camera lens means that only a small plane within this range will be sharp while wide open (low f-stop). The larger you make it – or “stopping down” – the more of your image will be in focus.
Large apertures (lower f/stops, like f2.8) result in a very shallow depth of field with only a few pixels of the subject in focus.
Depth of field can be adjusted by adjusting the f-stop, which also affects exposure (how bright or dark an image is).
You can blur out background distractions with a shallow depth of field, but you will need a smaller aperture in order to achieve this result.
A smaller f-stop setting, or “stopping down,” will allow you to have a deeper depth of field by decreasing the shutter speed.
Similarly, you can decrease the shutter speed for a shallower depth of field, but this will require you to bump your ISO.
Tricky Things About F Stop
Adjusting either your ISO also affects how bright your exposure is by default and potentially how many photons of light hit your sensor.
Adjusting one setting will likely require adjusting the other to compensate.
You can use a calculator to determine an appropriate exposure (brightness).
It defaults as ISO 200 with an f/11 aperture for 30 seconds, but you can adjust either parameter until it calculates values for the other.
But remember that you’ll need to adjust your ISO on top of whatever setting you use for aperture (or vice versa) if either of these two settings affects exposure by default.
For example, adjusting your f-stop from 11 to 16 will require you to increase ISO to compensate with a faster shutter speed or smaller aperture to maintain the same exposure (brightness).
An f/32 lens is an example of a large opening with a low depth of field, while an f/16 or lower number means that you can shoot at faster shutter speeds without needing as much light.
How To Calculate F Stop
There are generally two ways to calculate f stop: using your lens’s focal length or an online calculator.
You are assuming that you know either the width of your sensor (in millimetres) or the distance from its centre to the subject.
Then these methods can help you find out what aperture will work best for a particular scene – and thus determine how much light is hitting the sensor.
To calculate f-stop using your camera’s focal length, divide it by the size of its aperture (width in millimetres).
Like, a 50mm lens with an aperture diameter of 25mm will have an f-stop value of 50/25=20.
Narrow apertures (such as f/16 to f/22) let in less light and require slower shutter speeds.
Tips For Shooting F-Stops In Low Light Conditions
- To get a brighter exposure, either speed up your shutter speed (decrease the time allowed for light to hit the sensor) or open your aperture.
- If you need more depth of field – which means that more objects in front and behind your subject will be sharp rather than blurred out – then close down the aperture by increasing the f-stop number.
- In Manual mode, for example, just changing the aperture without changing the shutter speed will result in a darker or lighter image depending on which you adjust.
- Be careful that you don’t increase shutter speed too much or let in too little light, or else your shot will be underexposed (too dark).
- Likewise, if your aperture is set to a low f-stop number and your shutter speed isn’t fast enough to compensate, then the final image can also turn out darker than expected.
- Remember that every f-stop number represents an aperture setting in relation to the lens’s maximum aperture.
- A lesser-known benefit of fast lenses is that the wider the maximum aperture, the faster your camera’s autofocus system will perform, especially in low light.
- With practice, you will feel more comfortable setting the aperture and shutter speed and will have more control in manual mode.
Examples Of Photos With Different F Stops
A small aperture will let in less light, so it will take longer for the same amount of light to reach the sensor. A small aperture is a circular opening of the lens with short diameter.
An f/16 aperture setting will not only let in more light but will also increase the depth of field to make sure that your scene isn’t overexposed (bright) or underexposed.
Be careful when adjusting exposure while scrolling through the camera’s settings: an ISO number and shutter speed can affect what you see on screen and vice versa.
An f/22 aperture with a low depth of field will create the illusion that only your subject is in focus while blurring out distractions behind it:
A shallow depth of field with an f/11 aperture setting can help you blur out background distractions and direct attention to just one object – but this requires both faster shutter speed and a lower ISO.
An f/32 aperture is an example of a large opening with low depth of field, while an f/16 or lower number means that you can shoot at faster shutter speeds without needing as much light:
When adjusting exposure settings on your camera, remember to be careful not to bump up the ISO too high or the shutter speed too low – this can create an underexposed (too dark) image.
The lowest f-stop your lens can shoot with is called the maximum aperture.
Zoom lenses have a maximum aperture of f/2.8 or f/4, and some have a variable range.
Opening the faucet just slightly (i.e. a small aperture) takes longer to fill the glass than opening the faucet to full volume (i.e. the widest aperture), which fills the glass in a fraction of the time.
If you’re shopping for a lens that zooms, it’s normal for the lens to have a wider maximum aperture when it’s zoomed out than when it zooms in.
Different Lenses With Different F-Stops
- Wide-angle lenses, regardless of their focal length numbers (e.g., 18mm or 24mm), are not as sharp when you shoot at low f-stops around 11 to 16 because they have a shallow depth of field.
- Prime lenses, or other lenses with a fixed focal length, can handle a wider aperture because they have fewer moving parts. Based on your photography style, you should use a specific lens.
- This means that only objects closer to the lens will be in focus, while anything further away from it will appear blurred out.
- While some cameras can create an image with lower noise up through ISO 1600, don’t expect miracles even if your camera has higher maximum settings:
- Both aperture and shutter speed affect exposure by default, so these two variables must also compensate accordingly for darker scenes where there isn’t enough light available.
- An f/22 aperture is a great choice when you want to use an ultra-high resolution camera, such as the Canon EOS R, because it widens the depth of field and boosts image quality thanks to improved sharpness.
- As an example, a lens with a maximum aperture of f/2.8 lets in twice as much light as one with a maximum aperture of f/4.0.
As four main factors affect exposure – ISO number, shutter speed, lens focal length (or size), and aperture – you can use a cheat sheet to figure out what combination will work best for your given scene.
- An f/16 aperture with a low ISO number is perfect when there isn’t enough light available, while an f/22 setting works well too in brighter conditions:
- When adjusting exposure settings on your camera, remember that ISO numbers and shutter speeds can affect what you see on screen, while aperture may also need to be adjusted accordingly for each scene.
- A low f-stop number like f/32 won’t work well in dark conditions because the wider opening will let less light into your camera – which means that a slower ISO or longer shutter speed might have to be used instead.
So f/1.4 is a very wide opening (or larger aperture), while f/22 is a much smaller opening (or smaller aperture).
- Essentially, lens speed refers to the maximum aperture of your camera lens, and the “faster” the f-stop, the easier it is to capture moving subjects under low light and capture fast-moving subjects in low light.
What is f-stop vs aperture?
Diaphragm openings are called apertures.
The f-stop is a ratio of the focal length of the lens and the diameter of the entrance pupil that represents how much light can enter the lens through the aperture.
The aperture size reads inversely to its corresponding f-number.
What f-stop is sharpest?
The sweet spot of your lens is two to three f/stops away from the widest aperture.
Therefore, I find that f/8 to f/11 is the sharpest aperture on my 16-35mm f/4.
If you have a faster lens, like a 14-24mm f/2.8, you’ll need an f/5.6 to f/8 aperture.
How is f-stop calculated?
A number is assigned to the lens opening by using the formula f/stop = focal length/diameter of the effective aperture (entrance pupil).
If you look at the viewfinder or LCD screen of your camera, you’ll probably see the f/stop markings in one-stop increments written on the barrel of your lens or presented digitally inside your camera.