Aperture is one of the most discussed topics in the field of photography. Many like those who are very beginner photographers are usually confused about selecting this aperture size. This is obviously nothing critical. I was also confused about selecting aperture size. But, if we are planning for better photography, then we must know about aperture. At the same time, we must be master on selecting aperture size for doing photography.
What is Aperture?
Aperture is termed as a hole which allows the light to travel. This hole allows a definite portion of the cone of light to travel through it. This is what optics says. So what is an aperture in case of photography?
It is nothing different here. It is also a hole in the lens which allows the light from the subject to fall on the image sensor of the camera. Image clarity, image sharpness, image brightness, depth of field, shutter speed and many other things are depended on aperture.
What is Aperture Size?
Aperture is a hole as mentioned earlier. That means it has got a diameter. And obviously, it can be big or small. So for a particular apparatus like a camera lens, there is either fixed or variable aperture size. So, for allowing a definite amount of light to flow or pass there is a certain diameter of the aperture and that is the size of the aperture.
For any lens, there is a certain limit of aperture size. If the lens aperture size is variable, then there will be an upper limit and a lower limit. More the size of the aperture more the amount of light that can pass and lesser the aperture size, less the amount of light can pass through.
Aperture and depth of field are interrelated. Before explaining the relation, we must know about the depth of field. The depth of field is the area on the plane which becomes apparently sharp after focusing a lens. Let’s see the figure below and get more details about this.
Suppose, the red circle and the black circle are two apertures. The red one is comparatively bigger than the black one. ‘S’ is the subject from where the light is entering into the two holes or two different aperture sizes. Blue lines are the light path or light rays. Now, for the red aperture, the area within ACS are clear. Thus, this area is the field for this aperture, and the distance from the line AC up to S is the depth of field for the red aperture size.
For the black aperture, the area BDS is clear. Thus, this is the field for this aperture and distance from the line BD up to S is the depth of field for the black aperture size. Here the depth of the field has increased. So we can say, narrower the aperture, more is the depth of field than that of the depth for a wide aperture. So, you need to select a narrow aperture for getting more depth of field.
Large or Small Aperture Size for Selecting ISO?
What is ISO? It is the sensitivity of the sensor of the camera on the presence of light. If the aperture size is bigger, then the amount of light will be more on the image sensor. This will be vice versa for small aperture.
So, the larger the aperture less the ISO range is required and vice versa. But it depends on the exposure as well. If your exposure time is more than you can select a small range of ISO for smaller aperture size.
How Aperture Influences Shutter Speed?
If you select a large aperture, the light that will fall on the sensor will be more, and it will be ready to take photo faster. But if you have selected a small aperture, then your camera will take time to capture the photo due to less light. Again there is a relation with the ISO. If you have set a high range ISO, then the sensitivity of your camera will increase. In this case, your camera will take less time to capture the image. So, select faster shutter speed if you have selected narrow aperture and lower ISO.
Selection of Aperture Size in Different Types of Photography
There are lots of category of photography. For all types of photography, there is a certain range of aperture for getting specific types of photo. Again, photography is an art. It’s always you who will select the required one according to your will. But before that, you need to know the standard one. I shall discuss some common category of photography and the aperture size related to those.
Landscape photography is a common and very popular category of photography. Before going to the main discussion, I must talk about a common wrong idea about landscape photography. Many of my friends think that landscape photography is only applicable during daylight. If you are still with this wrong idea, then please forget it. You may know it further from my tips about Landscape photography.
Now come to the main discussion. Landscape photography is photography where a wide area is usually described through a photo. Here we need depth of field. And we already know that to get the depth of field we need narrow aperture. A wide aperture will either focus the foreground or background. It may focus only on the background as well. So, there is no confusion about using narrow aperture size for Landscape.
So far I have discussed landscapes in the daylight. Now if you want to have a landscape at night time then what should be the aperture? During the night there will be less light unless arranged artificially. Less light and a small aperture will allow very very limited light on the sensor.
For this reason, we may use a large aperture. But what to do if we want to get the depth of field? Well, there is a solution. We have to make the extended depth of field by using photoshop. If you want to know further then check tutorials on the Extended Depth of Field. You may also check my video tutorial on youtube which is also to the article.
It is very easy to understand selecting the aperture for the portrait if you have already read whatever is written in the article so far. Usually, we do capture outdoor portrait during golden hour. In that time there remains plenty of lights. Very easily you will be able to keep your ISO to a minimum level. In that situation, you can select the narrower aperture for getting the depth of field, and you can select a wide aperture size if you want less depth of field.
For indoor portrait, you have to consider the presence of light. If there is artificial lighting, then you have to keep that in your mind. Presence of light source either artificial or natural needs narrow aperture and less light needs the opposite.
Portrait in low light demands wider aperture. In this case, the depth of field is compromised. Fortunately, people are interested to shot the portrait with less depth of field. This tendency is more in low light where the background light will become a blur one.
Long Exposure Photography
If you are shooting long exposure during daytime then obviously you have to select smaller aperture size. During the daytime, you need to use filters for shooting long exposure photographs. Intense light may spoil your whole photo. So, besides using a filter, you need to use a smaller aperture for making a good photo. Again, it depends on the time of the day and the presence of light at that time.
If you are shooting at night, then you need to open up the aperture to a bigger size as the presence of light will usually be less. In this case, the depth of field as discussed earlier will be compromised. But, we can extend the depth of field by taking more photos and post-processing those on Photoshop. However, you can use a narrow aperture if the exposure time is more. Few practices will give you a clear idea about selecting aperture.
Macro and Close Up Photography
Macro and Close Up Photography are very demanding categories. Though many think that these are the same but in reality they are different. In both of these categories, we usually want to focus on a particular point. In these type of photography, we usually highlight any specific thing.
It usually becomes a part of the subject. In this case usually, a wide aperture is suggested. But, we should not be rigid with this. We can obviously select the narrow aperture for this type of photography. At the same time, we can extend the depth of field taking more than one photo according to necessity and blending them together.
A Blended Suggestion
Now I will suggest you forget about all type of photography. Before shooting any photo, you just think about the presence of light. If the amount of light is more, then you can narrow down your aperture.
If the light is less, you need to widen the aperture. Point to be noted that long-range ISO with less light also qualifies for narrow aperture. Again, irrespective of the intensity of light you need to select narrow aperture size to get the depth of field.
I always say and believe that photography is an art. Art is your midn’s baby. You know how you are going to use your mind. So, bring the setup in such a way so that it comes in line with your mind. Aperture size is just a passage which allows light to pass through. Understanding the presence of light, you need to select the aperture size. Again you need to keep it mind about the depth of field. The depth of Field is important for almost all the photos, and it is directly related to aperture size.
Finally, my suggestion is, understand aperture at first. Then taking few guidelines do experiment with different aperture sizes. This is the best way to be master on using perfect aperture for any category of photography.