Aperture/Shutter/ISO

All cameras from the most complex to the most basic camera need to obey the simple triangle of exposure. Aperture, Shutter and ISO

Aperture : Think of it as the iris of our eyes, if an environment is too bright, the iris close up to restrict the amount of light entering our eyes, if it gets dark, it dilates and more light enters.

Similarly, all cameras have this 'iris' called the aperture to control the light entering. Some cameras have fixed apertures while most in the market now have variable ones. Usually denoted by the letter ' f ' followed by a stroke ' / '. Like “f/2.8, f/4.1, f/8.0...” how the number comes about is simple but let's not get too technical at this point. Remember, the smaller the f-number the bigger the aperture and more light enters.

Shutter : This is the “eyelids” of the camera system. Our human eyes has the 'shutter' open all the time because we need to see motion. However, cameras only need the shutter to be open for a fraction of time to 'freeze' a frame in time to be captured by the sensor to become a still photograph.

There are 2 types of shutters in cameras these days, the mechanical and electronic. Most point and shoot cameras uses the electronic shutter while many Digital SLR (Single Lens Reflex) cameras use either mechanical or a combination of both shutters. Regardless of which shutter type, the function is the same and it shouldn't bother you at all. The longer the shutter time, the longer it stays open and more light passes through.

ISO : Used in the film days to denote the sensitivity of film to light, in present digital photography days. It does mean the sensitivity of the image sensor to light to some extend, but I would rather call it the “amplification” than “sensitivity”. In short, the higher the ISO number the more sensitive the sensor is to light, and therefore it can capture images better in dark environments. Common numbers range from 50 to 800. Most modern day cameras offer ISO up to 6400 and even 12800. Of course there are trade-offs for higher ISO called digital 'noise' but we'll cover that later.

So now we have 3 elements all with the ability to control the amount of light it wishes to let through.

Aperture: Bigger aperture (smaller f-number), more light enters, photograph appears brighter

Shutter: Longer exposure, more light enters, photograph appears brighter

Sensor (ISO):Higher number, more sensitive, photograph appears brighter

Light--> Aperture-->Shutter--> Sensor

Exposure Triangle Cheat Sheet

With this knowledge in hand, we can go on to learn how each point of the triangle affects the type of picture produced. Each element controls a certain element in how the photograph will turn out. How do we know what to adjust and what to use? That is where practice comes into the picture.