Basic Photography principles that may improve your shots

I have always been interested in photography however around 5 years ago my passion for taking that perfect picture got much bigger. Everything I have learnt is from photography magazines, youtube and reading articles online. I keep developing and keep learning new things all the time. When I look back at photos I took 3 years ago I see how much more I know now and how I could have done it better. Even just in the last year I have leant so many new things. Traveling means I have been meeting many people with the same passion as me and we have been able to share tips and teach each other.

I am really passionate about taking photos and I am keen to help others. This is my guide in how to help you, which is what I have learnt from all the different places.

Basically there are 3 main things to understand about how to control the image your camera generates.

  1. Aperture
  2. Shutter Speed
  3. ISO

The combination of these 3 things together create your photo and control how much light your photo will get (exposure)

But before explaining these things it worth understanding how the basic functions of a camera work.

When you press the shutter button to take a photo. A hole will open in the camera to allow light to come in. This light will hit the camera sensor. The light that hits the camera sensor gets turned into an image based on the light that comes in.



Aperture is physically how wide the hole opens that lets in light. This is represented on cameras as the f number.
The lower the f number is the wider the hole the opens. e.g. f1.4 is wider than f16.


When you have a low f number (bigger hole), you let more light into the sensor and you also get a better depth of field. When you have a high f number (smaller hole), less light can get in and the image will have more in focus

Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also – this means if you increase one and decrease the other you let the same amount of light in – very handy to keep in mind).

Fun test: if you put your hand close to your eye and focus on it. Your pupils will become big (wide aperture). If you then look in the distance your pupils will become smaller again.

Shutter Speed

How long the hole is open to allow light in. So the longer it’s open, the more light can get in. It’s kind of like if you take the plug out of a full bath tub, the longer you leave it open, the more water goes through the hole. But in our example it’s more light getting to the sensor.

One thing that’s important to know is that when light is coming through the hole to hit the sensor, it’s constantly drawing the image onto the sensor. So if you move the camera or the subject is moving and the sensor is exposed to the light for too long then the image will be blurred. This happens a lot when people take pictures at night time without a flash.

Shutter speed on your camera is represented in seconds. 1/800 would phyiscally translate to for 1 800th of a second the light was allowed in.


Sensitivity of the sensor. This concept comes from the days of using film in cameras (obviously people still do). You can buy different film depending on how sensitive you want it to be to light. The difference is that in digital cameras it’s moved from chemicals on film reacting to light to electronic diodes on a sensor reacting to light.

The drawback to having a very sensitive ISO is that the image becomes more grainy the higher the ISO gets. This concept is referred to as ‘noise’. So if the image is grainy photographers would refer to the image as being to noisy.

Example of a noisy image (grainy)

ISO is an easy thing to forget about for a lot of people but if you want images that are truly print quality you need to make sure they are not compromised by noise.

Using these 3 things to get the right exposure for a photo

With this in mind we can now explain the 3 main things to understand about control the light that comes in to create your picture

Exposure is how bright the image is from the amount of light that has been received on the sensor. If the image is under exposed it will be too dark so it didn’t get enough light. If the image is over exposed it will be too bright because it recieved too much light.

To get the correct exposure it is a balancing act between the 3 things we control
a = aperture, s = shutter speed, i = iso

Lets pretend that the correct exposure for a picture is 100 units of light (whatever that may be). And that the 3 things we control to make a picture correctly exposed need to add together to get 100 units of light. Any result under 100 would mean the picture is under exposed and any result over 100 would mean the picture is over exposed.

eg. Correct Exposure (100) = a + s + i

Here is how some different scenarios could play out

Example 1

If we make the aperture low. a=10
we need to make the shutter open longer and/or the iso more sensitive to get to 100 units of light
e.g.. Correct Exposure (100) = a(10) + s(50) + i(40)

Example 2

if shutter speed is fast. Lets say for our formula it is 5 light units
then to compensate we
e.g.. Correct Exposure (100) = a(60) + s(5) + i(35)

Example 3

We make aperture low and shutter speed low
then to compensate we only can use the iso
e.g.. Correct Exposure (100) = a(10) + s(10) + i(80)

Enough of the theory how do i do this on my camera

I use a canon so on the dial on the top of the sir you can see
Av = Aperture
Tv = Shutter Speed
M = Manual

For Nikon is nearly the same
A = Aperture
S = Shutter Speed
M = Manual

When you change to one of these settings, lets say Av.. it basically means you are telling the camera what you want to control the Aperture, but the rest is still automatic

Scenarios and suggested settings

Nice portrait shot Use Av and make the aperture as low as possible. Wide aperture (low f number)
Someone running / bird flying / car race Use Tv – set this to a fast shutter speed. Something like 1/1000 or above depending how fast they’re moving
Night sky / stars Use Manual – set to shutter speed to 30 seconds, aperture – set to as low as possible (less than f2.8 should allow a good capture). Put the camera on a tripod. Use a remote or 2 second timer so you don’t accidentally move the camera
Street photography Use Av. I set to a low aperture but I usually prefer around f8 so more things are in focus. (it depends on what you are trying to capture as always)
Mountainous Landscape Use Av – set to a high f number so most of the scenery is in focus. Ideally have on a tripod as with a high f number there will be less light allowed to the sensor so your shutter speed may not be so fast and your picture may get blurry otherwise
Fireworks Use Tv – (tripod if possible) set to a slow shutter speed. This will allow the light from the fireworks to create light trails in the picture
Isolating words in a book Use Av – low f number so the depth of field is

Now the best image to convey how they work together

If you can understand the following this image, you get it. It shows the impact of all three things. Aperture, shutter speed and ISO on an image


I recommend you look at this for a while to make sure you understand it. If you don’t then feel free to message me and hopefully I can add more information that will get you there

Hope this helps any budding photographers out there!

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