Oubliez le triangle d'exposition ! - - - et comprendre les STOP (ou Diaph, IL, EV...)

Introduction

This tutorial aims to demystify the concept of exposure in photography by introducing the four key factors that influence it, rather than the traditional three. You'll learn about "stops," how to adjust your settings for optimal exposure, and how to utilize manual mode effectively.

Step 1: Understand the Four Factors of Exposure

To achieve perfect exposure, it's essential to grasp the four key components that govern it:

1. Aperture (Diaphragm)

   • Controls the amount of light entering the lens.
   • Measured in f-stops (e.g., f/1.8, f/4).
   • A lower f-stop means a wider aperture and more light.

2. Shutter Speed (IL)

   • Determines how long the camera's sensor is exposed to light.
   • Faster shutter speeds freeze motion, while slower speeds can create motion blur.

3. ISO (EV)

   • Adjusts the camera's sensitivity to light.
   • A higher ISO allows for shooting in low light but may introduce noise.

4. Exposure Compensation

   • Adjusts the exposure level to achieve the desired brightness.
   • This can help correct overexposed or underexposed images.

Step 2: Learn About Stops

Understanding stops is crucial for manipulating exposure:

• A "stop" is a doubling or halving of the amount of light.
• You can increase exposure by:
  • Opening the aperture (lowering the f-stop).
  • Slowing down the shutter speed.
  • Increasing the ISO.
• Conversely, to decrease exposure, do the opposite of the above adjustments.

Step 3: Compensate Changes Between Factors

When you adjust one factor, you may need to compensate by adjusting another to maintain the same exposure level:

1. If you increase your aperture (wider), you may need to:

   • Decrease the shutter speed (faster) or lower the ISO.

2. Conversely, if you decrease the aperture (narrower), you would:

   • Increase the shutter speed (slower) or raise the ISO.

Step 4: Utilize Manual Mode

Switching to manual mode allows for full control over your camera settings:

1. Set the Aperture

   • Choose your desired f-stop based on the depth of field you want.

2. Select Shutter Speed

   • Adjust according to the motion in your scene.

3. Adjust ISO

   • Set it based on your lighting conditions.

4. Use the Camera's Metering

   • Check the camera's exposure meter to ensure your settings provide a good exposure.

Practical Tips

• Experiment with different combinations of aperture, shutter speed, and ISO to see their effects on exposure.
• When shooting in changing light conditions, regularly check and adjust your settings.
• Use a tripod for slow shutter speeds to avoid camera shake.

Conclusion

Understanding and controlling the four factors of exposure—aperture, shutter speed, ISO, and exposure compensation—will greatly enhance your photography skills. Practice using manual mode to become more comfortable with these concepts. As you gain experience, you'll be able to achieve the perfect exposure for any scene. Happy shooting!