So what is aperture?!
It is an element inside the lens it self.
We talked about how we use a lens to get and focus the light and direct it to the camera sensor. So inside the lens, among with many other components, there is the diaphragm. Check the picture on the left, although I'm sure that your are familiar with what I'm saying.
Now lets see how aperture affects our photos.
Aperture has the symbol f in your camera settings. So basically by changing the aperture value, the fnumber, we control the diaphragm inside the lens.
That means that this little hole opens and closes.
And of course you guessed it right!
The more it opens, the more light comes through the lens to the camera sensor.
The more it closes, the less light comes through the lens to the camera sensor.
And similar to the shutter speed, it controls the amount of light, making your photo brighter or darker BUT
it also affects your depth of field!
Now what is the depth of field?!
As depth of field, we call that field or area inside our frame that things will appear sharp and focused and everything outside that field will be out of focus.
Yeah, i know that's what you have been searching for!
How to create that blurry background that makes the photo look so good! I know, it was the first thing i ever searched as well!
That is called bokeh.
Do you notice how only the small drop of oil is the only thing focus and everything behind and away from that is blurry?
That is controlled by the aperture.
Aperture has a minimum and a maximum value.
Now it might be a bit confusing in the begining but you will get the grasp of it with time.
The lower the number is, the more the diaphragm(or the hole) opens. That allows more light and also creates a narrow depth of field.
The bigger the number is, the more the diaphragm closes. That allows less light and also creates a wider depth of field.
So in this example I wanted to shoot a landscape picture and have everything in the frame be crip and focused. In order to accomplish this I used ahigh fnumber like f6 or f7.1.
In this example, I wanted to make a portrait and I wanted my subject to stand out in the frame, by blurring the background.
In order to accomplish this I used a lower fnumber, like f1.8 or f1.4. That creates that bokeh effect in the picture.
The maximum aperture value is always indicated in every lens and its quite the selling point, when chosing a lens.
Lenses come in two types, when it comes to aperture. Either it is going to a be fixed or variable.
Usually entry level zoom lenses have a variable aperture. That means that the maximum aperture changes according to the focal length.
Lets take for example a kit lens like the 18-55mm f3.5-5.6. That means that the maximum aperture at 18mm will be f3.5 and at 55mm it will be f5.6.
Which comes with its pros and cons, which we will see on another chapter.
On the other hand a fixed aperture means that the aperture will remain the same through the whole zoom range of the lens.
So according to the lens you will get either a fixed aperture or a variable one. Also higher end lenses come with a higher maximum aperture, like f1.4, which means they allow more light to enter your camera sensor, but also create a better and smoother bokeh. These lenses also are way more expensive, but in my opinion they are totally worth the investment!
So to sum up!
- Aperture controls the diaphragm inside the lens.
- It has a maximum value and minimum value.
- Maximum is the lower value, eg. f1.4 and minimum is the highest value eg, f22
- The lower the fnumber is eg, f1.4, the more the diaphragm opens, the more light it allows to pass and the narrower the depth of field will be. (blurry background - portrait)
- The higher the fnumber is eg, f13, the more the diaphragm closes, the less light it allows to pass and the wider the depth of field will be. (crispy image across the whole frame - landscape)
Here is a picture to keep as a cheat sheet!