Apprenez-en davantage sur le triangle d’exposition

Exposition longue, grande profondeur de champs: f/11, 1/8 seconde, 200 ISO

Le mot photographie vient du grec ancien : photos (lumière). C'est pourquoi il est important de bien comprendre et maîtriser l'exposition en photographie. La vitesse d'obturation, l'ouverture du diaphragme et les ISO sont les trois éléments qui forment le triangle d'exposition.

La vitesse d'obturation est déterminée par la durée pendant laquelle l'obturateur reste ouvert. Le capteur des appareils photo numériques capte plus de lumière lorsque l'obturateur reste ouvert plus longtemps. Une vitesse d'obturation lente (par exemple 1/10 de seconde) peut être utilisée dans un environnement faiblement éclairé ou pour créer un flou de mouvement (cascades, traînées de pluie) tandis qu’une vitesse d'obturation rapide (par exemple 1/1000 seconde) est utilisée pour figer un mouvement comme un oiseau en vol.

Exposition rapide, courte profondeur de champs : f/5.6, 1/800 seconde, 1250 iSO

L'ouverture (f/N) est une abréviation pour l’ouverture du diaphragme. Une petite ouverture comme f/22 ne laisse pas passer beaucoup de lumière à travers l'objectif, mais elle offre une grande profondeur de champ et est couramment utilisée en photographie de paysage. Une grande ouverture comme f/5.6 laisse passer plus de lumière à travers l'objectif et fournit également une profondeur de champ étroite ou courte.

L'ISO est lié à la sensibilité du film à la lumière ou bien la sensibilité du capteur d'image à la lumière sur les appareils photo numériques. Par une journée ensoleillée, les photographes utilisent généralement un ISO bas (100) mais dans des situations de faible luminosité (temps couvert, nuit), ils augmentent l'ISO. Notez qu'un ISO élevé (3 200 ou plus) crée du bruit dans votre image (voile granuleux).

Learn more about the triangle of exposure

Long exposure, wide depth of field: f/11 for 1/8 second, ISO200

The word photography comes from the ancient Greek: photos (light). Understanding and mastering exposure is therefore essential in the art of photography. The shutter speed, the (diaphragm) aperture and the ISO are the three elements, which form the triangle of exposure.

The shutter speed is determined by how long the shutter stays open. The sensor in digital cameras will capture more light when the shutter stays open longer. A slow shutter speed (for example 1/10 second) can be used in low-light environment or to create a motion blur (waterfalls, rain streaks) while a fast shutter speed (for example 1/1000 second) is used to freeze a movement like a bird in flight.

Fast exposure, short depth of field: f/5.6 for 1/800 second, ISO1250

The aperture (f/N) is short for diaphragm aperture. A small aperture like f/22 does not allow a lot of light to pass through the lens, however it provides a wide depth of field and is commonly used in landscape photography. A big aperture like f/5.6 lets more light pass through the lens and it also provides a narrow or short depth of field.

The ISO is related to the film sensitivity to light or image sensor’s sensitivity to light on digital cameras. On a sunny day, photographers typically use a low ISO (100) but in low-light situation (overcast day, night), they increase the ISO. Note that a high ISO (3,200 or more) will create noise in your image (grainy veil).

Introducing Creative Nature Photography online course

I am happy to announce my two-part online course Creative Nature Photography (courses are available in English and in French). If you are looking to improve your creative skills, this is the course for you. Divided in two parts: Composition and Wildlife Photography, the course covers keys elements of composition, use of light, shutter speed, preparation for a field trip, encounters with wildlife and so much more.

The presentation is given on Zoom so you can ask your questions after the lecture and interact with our small group of 10 people maximum.

You are not left on your own with a video and reading material.

The first part of the course in English starts on Tuesday 23 February. The course in French starts on 24 February. I have classes scheduled in the morning and in the evening to accommodate you no matter your time zone.

Sign up today for one part only, or save $10 by signing up for both parts.

Photo Technique: What is the triangle of exposure?

It allows you to control the exposure by setting up the shutter speed, lens aperture and ISO based on the intended mood of your photograph. A slow shutter speed will change rain or snow in streaks; it can also be used to isolate the subject. A small lens aperture gives a wide depth of field, where all elements of the image are in focus. Low ISO can be used for a long exposure.

Slow shutter speed

Small lens aperture

Photo Technique: How to reduce noise in an image?

There are a few actions you can take:

• Expose to the right by either opening up the lens aperture or by using a slower shutter speed. An underexposed image later brightened on a computer will result in a lot of noise and other artefacts.

• Determine your camera’s high ISO capability by conducting a simple test. Place your camera on a tripod and take the same photograph of a subject with dark areas, at various ISO starting at 100 all the way up by increment of full stops. Verify the progression in the amount of noise by enlarging each image on your computer screen.
  

Photo Technique: : How to obtain maximum focus?

Use a small aperture such as f/16, low ISO, make sure the back of your camera is parallel to your subject and use your tripod.

The Basics of Photography

Composition, exposure, shutter speed, ISO, aperture, opening up, spotlighting, centre-weighted meter: you might be familiar with some of these terms but it’s not always obvious how to adjust your camera accordingly. I offer half-day and multi-days workshops to help you understand and practice the fundamentals of photography. Once you master the basics, you’ll be able to take manual control of your camera and get better results.

All my workshops are given in the field for a hands-on experience. Get in touch so we can arrange for a workshop.

Triangle of exposure

Three elements constitute the triangle of exposure: aperture, shutter speed and ISO:

• Aperture (f/N): light passing through the lens

• Shutter speed: how long the shutter stays open

• ISO: image sensor’s sensitivity to light

A small aperture (i.e. f/16) gives a deep depth of field and is usually used for landscape.

A fast shutter speed (i.e. 1/1000 sec) is used to freeze motion, like birds in flight or action shots. It also gives a shallow depth of field.

A slow shutter speed (i.e. 1/4 sec) is great for motion blur like milky water effect or rain streaks. Slow shutter speed is also used for night photography or poorly lit areas. In any case, a tripod is highly recommended for long exposures.

Before you adjust the aperture, shutter speed and ISO on your camera, you need to ask yourself: What effect do I wish to create? What is the mood of my image? What am I trying to tell?

Use the light meter in your camera to help you get the proper exposure. Light is measured in Exposure Value (EV) and typically displays in cameras from - 3 EV to + 3 EV

-3 _____ -2 _____ -1 _____ ∆ _____ 1 _____ 2 _____ 3

under exposed correct expo. over exposed

Once you’ve taken your shot, check the histogram and readjust your exposure if necessary.

Time to practice. Let me know how it goes!

f/13, ISO 200, 1/25 sec

f/5.6, ISO 800, 1/500 s

f/11, ISO 100, 1 sec

f/5.6, ISO 800, 1/800 s

f/9, ISO 800, 1/30 s