What is the exposure triangle and how does adjusting the three parameters that make it up affects your photography? Thomas Faso, assistant director at Gosselin Photo Vidéo in Montreal, answers this question in no time!
What is the exposure triangle?
It is simply three settings that will allow us to adjust the exposure, so the amount of light that is perceived by the sensor – this light that enables us to create an image. These three settings are the ISO sensitivity, the diaphragm aperture, and the shutter speed.
There are different ways to handle these parameters – Tomas Faso always starts by setting his aperture first.
The Diaphragm Aperture
The aperture consists of a diaphragm in the lens which will simply close and open to let in more or less light.
Before determining the aperture, we must ask ourselves if we want to obtain a background behind the subject that is blurred or sharp, and respectively choose a large or small aperture.
For example, if we are on large apertures at f/2.8, f/1.4 or f/1.8, we will have a very nice blurred background, a very short distance of focus, and inevitably, more light that will be projected on the sensor.
On the other hand, the higher the aperture, which is called "f" (f/stop): f/4, f/6.3, f/8, f/16, etc., the more the background will be clear behind the subject, the more we will have a greater focusing distance and less light will reach the sensor.
A large aperture is best used, for example, when shooting groups of people (some of whom are closer, others further away) – the area of sharpness being deeper, it is easier to get the whole group in focus.
After having made this adjustment, we get inevitably more or less light, and therefore exposure in on our sensor. That's when Thomas chooses to continue with a second setting.
The Shutter Speed
The shutter speed is determined according to the subject to be photographed. For example, if we are shooting sports or wildlife where the subject is moving quickly, we usually go to very high speeds: 1/400th and more.
On the other hand, if we are facing a slow or almost motionless subject such as in landscape or portrait photography, we can opt for lower speeds without the risk of obtaining motion blur due, for example, to the movement of the subject during the period the shutter lets the light enter the camera.
We can speak of low speed when we are at 1/200th, 1/150th, 1/80th of a second and more.
The lower the speed, the longer the sensor is exposed and therefore the more light it receives. The higher the speed, the less light we get. This is where the third setting comes into play which will compensate if we have enough or not enough light.
The ISO Sensitivity
So, if we see that after setting the aperture and shutter speed, we don't have enough light, we can compensate by increasing the ISO sensitivity: ISO 200, ISO 400, ISO 800, for example. If there is too much light, the ISO sensitivity should be lowered.
If you go down to ISO 100 (or the lowest ISO value your camera allows), and you are outdoors and the image is still overexposed, you could go back to the previous two settings – see if you can close the aperture further or reduce the shutter speed without compromising the desired result - or simply use an ND filter to control the light input, absorb some of it and prevent it from reaching the sensor.
So what about this triangle?
These three settings together form the exposure triangle and the overall exposure. Whether in digital or film photography, the dynamic between these three parameters is exactly the same.
Each of them has an impact on the amount of light that will be found in the photo. Practice, trial and error, and why not a little photography course at Collège Gosselin, will allow you to understand and master the relationship between them, enabling you to obtain images that match the ones you have in mind!
To learn more, you can read our blog posts about ISO, aperture and shutter speed.
And if you have any further questions, feel free to stop by our stores and talk to one of our advisors.
