Basics of Photography: How your phone or camera creates an image

Basis of photography

Did you know process to create the image is the same as the professional cameras as it is on a phone? The process has been same ever since the first photo was taken! This post is not about the difference between your phone camera and a DSLR. This post is to help you understand your camera and how it takes an image.

To create a picture you require a lens and a sensor (film in old cameras) to capture the light and the lens makes sure that your image is in focus.

Now that you know how a picture is created, you need to understand how to get the best quality images. For that, you need to know what is an exposure. 

In simple terms, it’s the amount of light that falls on the sensor. Too little light and your image will be dark and too much light and your image will be too bright which means your image will be completely white. Simple isn’t it? Exposure is the main reason why most of stays away from manual settings on your camera.

Let me show you an example of an under-exposed image (too less light falling on your sensor), over-exposed (too much light falling on the sensor) and perfectly exposed image.

To control the exposure you have three tools at your disposal and those are the shutter speed, Aperture and ISO. 

Funny thing is, if you see those professional cameramen with those big cameras, they are just controlling these three aspects to get those amazing images. Hopefully, by this, you should understand how important are these tools of any camera. 

I know, some of you haven’t touched any of these settings when you use the camera on your phone or maybe not even on your camera itself! That’s because your phone and your camera would be in “auto mode” (you mostly can’t change these settings on your phone). What does that mean? Your equipment adjusts all the three parameters to get you the best possible outcome or at least thinks that it is the best outcome! 

It’s like riding a scooter and a bike! A scooter(auto mode) makes all the necessary gear changes which means it just tries to ride smooth. But on a bike, you control the gears giving you the benefits of shifting down or up whenever you need the power. But make a mistake and there is no turning back.

Now that you understand the importance of Exposure and how it is controlled. Let me take you through the three parameters (also known as the exposure triangle). Once you get the hang of using these tools then a whole new window of photography will open up. You will realise how all professional photographs are taken.

Let me take you through the three parts of the exposure triangle and how it affects exposure:

Shutter speed

The shutter speed is how long the sensor is on exposure to the light. Let me make it easier for you to understand this. When light falls on the sensor or the film of the camera an image is produced, the longer you keep the shutter open the more light can fall on the sensor brightening up the image. So the slower the shutter speeds means the shutter remains open for a longer period taking in more light the brighter the image and the faster the shutter means the lesser light on the sensor.

Shutter speed is depicted by the seconds. Example 1/10 is a 10th of a second shutter speed with less than a second. Most basic DSLR can go all the way to 1/4000 of a second. That should be fast enough for most use cases.

Photo by Kaboompics .com on

So do you need a fast shutter speed or a slow shutter speed? This mostly depends on the situation. In the evenings you might just use a faster shutter speed not to overexpose your shot. The opposite is true when you have less light, for example, indoor or at night. You will want your shutter speed to be low enough to capture enough light to make the image well exposed. But a too slow shutter speed and you can get motion blur in you image (more on this when I cover shutter speed in detail). Playing around with shutterspeed can give some amazing results.

Understanding your shutter speed also depends on other settings(ISO and aperture).


Aperture is the opening in the lens that lets light in on the sensor. You are able to control this opening making it as wide as possible or as small as possible to let in as little light that the lens can. See the below image and you will get a better understanding

By KoeppiK – Own work, CC BY-SA 4.0,

The aperture value is known as an f-stop or f-number and is written as f/<value>(example: f/2.0). This value or range will be written on your lens and it is an important parameter when selecting a lens. 

Smaller apertures are used when there is enough light and the situation requires more of the image in focus. For Example, Landscape photography where the photographer would want to capture the whole scenery and keep everything in it as sharp as possible. 

Apertures are written backwards, what do I mean by that? An aperture value of f/2.5 is wider than f/5. 


ISO refers to the sensitivity of your sensor or film to light. The higher sensitivity the brighter your image is going to be, but that is going to also bring in a lot of grain to your picture. So it is always recommended to use lower ISO so that you get the best quality images.

This is not always the case. There are times like at night where you would want to use a higher ISO to get a bright enough image, but having the right balance between your Shutter speed, aperture and ISO will make all the difference. That said if you are just starting to use a DSLR or a manual mode of a camera that lets you choose your ISO then start with the lower values.


To understand how a camera works and how a picture is taken, you need to understand the exposure triangle. It is easy to understand but can be a bit confusing when you start using, it was for me. Once you start using it you will find the difference between the automatic mode and manual mode when you should use either of the settings.

Stay tuned and subscribe to my newsletter so that the next few blogs on photography will be in-depth. Let me know if this was interesting and if anything is required to be added or change in this post.

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