What is Exposure in Photography ?

Exposure is Is one of the most fundamental aspects of Photography, This is the Key thing you need to master if you want to become a successful photographer, You will often here photographers are talking about this term.”Exposure” is simply the process of letting light through the Camera’s lens to illuminate or expose the digital sensor to produce an image.

EV(Exposure Value) is a single number used to describe the many permutations of aperture,ISO and Shutter Speed.Each EV step is equal to a one-step adjustment of shutter speed,ISO and Aperture and it’s typically used when we talk about exposure compensation and bracketing.
How can I get the right exposure for my image ?
Basically there are three parameters which controls the exposure value and these are –
  1. Shutter Speed
  2. Aperture
  3. and ISO
A good exposure is nothing but the perfect combination of these three parameters.So in order to get the optimum value of those three parameters,you need to determine three things :
  • How much light passes through the lens ? (Aperture)
  • What will be the length of time that light passes through the lens ? (Shutter Speed)
  • How sensitive to light the sensor is ? (ISO)


These settings can be balanced in numerous ways to produce a “Correct” exposure in terms of brightness but each individual settings will have a profound effect on the image.
Okey,hope now you are getting the point of balancing the exposure,So now,let us understand the each parameter individually.
Shutter Speed : All cameras contain a shutter,which may be either electronic or a mechanical unit that physically opens and closes in front of the camera’s sensor to allow in or shut-out the light.The shutter speed in your camera determines how long your sensor is exposed to light,Which explains why it’s also referred to as the “exposure time”.The effect it will have in your image depends on whether there’s any moment in the scene : Slow  shutter speed will result in moving subjects appearing blurred,while fast shutter speeds can “freeze” the moment.If there is no moment in your subject (For suppose you subject is a building or any still object like that),then all shutter speed will give you an equal result.
What happens on pressing the Shutter ?
The shutter inside most cameras uses a pair of blades known as “Curtains”.The first curtain opens to start the exposure,then the second follows to end it.The length of the time it takes for this to happen is the shutter speed or exposure time,and determines the amount of movement blur that’ll appear in your image.
Aperture : Aperture is a hole or iris in the camera’s lens which allows light to pass through to the camera sensor.Today all cameras have a variable aperture,so you can set the size of the hole precisely to match the prevailing light conditions.As it’s not intuitive ,aperture is probably the most difficult of these parameters.
When you increase the size of the aperture,or “open up” the lens,you allow more light to reach the sensor.This reduces depth of field(Simply,this is the amount of the scene,that will appear sharp in your image: the greater depth of field,the more elements will appear to be in focus.)so less of the scene appears in focus,but it allows a faster shutter speed and/or a lower ISO to be used.

ISO : The ISO amplifies the signal that the sensor receives,effectively making it more sensitive to the light.This is a bit like turning up the volume on a radio.However,just as this can increase the background “noise/gain”,high ISO settings can results in noisy images as non-image-forming elements are amplified.This noise is known as “Chroma”noise.Low ISO settings indicate low sensitivity,while high ISO equate to high sensitivity.On most of the mid range DSLR cameras we get a native ISO range of  ISO 100 -ISO 6400,or higher.
As a general rule,it’s always best to use the lowest ISO settings that you can.


3 thoughts on “What is Exposure in Photography ?”

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