What Are Stops in Photography
What is a Stop?
In photography, a “stop” is a unit of measurement that represents a doubling or halving of the amount of light that reaches the camera sensor. Adjusting your exposure by one stop means either doubling the exposure (making the image brighter) or halving it (making the image darker).
The Exposure Triangle
If you've not already read it, check out my guide to the Exposure Triangle by following this link. Otherwise, we'll just have a quick recap: the three main settings that control exposure are:
Aperture: The size of the lens opening.
Shutter Speed: The duration the camera’s shutter is open.
ISO: The sensitivity of the camera sensor to light.
Adjusting by Stops
1. Aperture (f-stop)
Increasing by one stop: If you go from f/4 to f/2.8, you double the amount of light entering the lens.
Decreasing by one stop: If you go from f/4 to f/5.6, you halve the amount of light entering the lens.
2. Shutter Speed
Increasing by one stop: If you go from 1/60s to 1/30s, you double the exposure time, allowing more light to hit the sensor.
Decreasing by one stop: If you go from 1/60s to 1/125s, you halve the exposure time, reducing the light.
3. ISO
Increasing by one stop: If you go from ISO 100 to ISO 200, you double the sensor’s sensitivity to light.
Decreasing by one stop: If you go from ISO 200 to ISO 100, you halve the sensitivity.
Balancing Exposure
To achieve a balanced exposure, you often need to adjust these settings in tandem. For example, if you increase the aperture by one stop (making the image brighter), you might need to decrease the shutter speed by one stop (making the image darker) to maintain the same exposure level.
Example Scenarios
Example 1: Portrait Photography in Low Light
Scenario: You’re taking a portrait in a dimly lit room.
Current Settings: f/4, 1/60s, ISO 800
Desired Adjustment: You want a shallower depth of field to blur the background more, so you open the aperture to f/2.8 (increasing by one stop).
Balancing the Exposure:
Shutter Speed: Decrease from 1/60s to 1/125s (decreasing by one stop) to maintain the same exposure.
ISO: Alternatively, you could lower the ISO from 800 to 400 (decreasing by one stop).
Example 2: Landscape Photography in Bright Sunlight
Scenario: You’re capturing a landscape on a sunny day.
Current Settings: f/11, 1/250s, ISO 100
Desired Adjustment: You want a faster shutter speed to freeze the motion of leaves in the wind, so you increase the shutter speed to 1/500s (decreasing by one stop).
Balancing the Exposure:
Aperture: Open the aperture from f/11 to f/8 (increasing by one stop).
ISO: Alternatively, you could increase the ISO from 100 to 200 (increasing by one stop).
Example 3: Action Photography at a Sports Event
Scenario: You’re photographing a fast-moving sports event.
Current Settings: f/5.6, 1/500s, ISO 400
Desired Adjustment: You need a faster shutter speed to capture sharp images of the action, so you increase the shutter speed to 1/1000s (decreasing by one stop).
Balancing the Exposure:
Aperture: Open the aperture from f/5.6 to f/4 (increasing by one stop).
ISO: Alternatively, you could increase the ISO from 400 to 800 (increasing by one stop).
Practical Tips
Use the Exposure Meter: Most cameras have an exposure meter that helps you see if your settings are balanced.
Practice: Experiment with different combinations to see how they affect your images.
Understand Trade-offs: Each setting affects not just exposure but also other aspects like depth of field (aperture), motion blur (shutter speed), and noise (ISO).
Understanding how to adjust settings by stops gives you greater control over your photography, allowing you to creatively and technically achieve the desired results
Header image CC-BY-SA-3.0 remixed from https://commons.wikimedia.org/wiki/File:Aperture_diaframma.jpg