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Exposure Time Calculator

Use our Exposure Time Calculator to quickly find the correct shutter speed. Easy, fast, and accurate for photography beginners and pros alike.

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Photography is all about capturing the right moment with the perfect light. One key factor in this is exposure time, also known as shutter speed. Using the wrong exposure can make your photo too dark or too bright. That’s why we developed the Exposure Time Calculator – so you can easily calculate the correct shutter speed for any scene.

Whether you’re a beginner or a pro, this tool saves time and ensures your photos look just right.

What is Exposure Time?

Exposure time is the length of time your camera’s shutter stays open. It controls how much light hits the camera sensor. Too short, and your photo is dark. Too long, and it becomes overexposed.

It’s measured in seconds or fractions of a second. For example, 1/250 means the shutter is open for one two-hundred-fiftieth of a second.

How Exposure Time is Calculated

The Exposure Time Calculator uses the standard photography formula:

t = (K × N²) / (L × S)

Where:

  • t = exposure time in seconds
  • N = aperture (f-number)
  • L = luminance (brightness of the scene in cd/m²)
  • S = ISO sensitivity
  • K = calibration constant (default 12.5, can be customized)

This formula ensures your shutter speed is perfect for the light conditions, aperture, and ISO you choose.

How to Use the Exposure Time Calculator

Using our calculator is simple:

  1. Enter the aperture value of your lens.
  2. Enter the ISO of your camera.
  3. Enter the scene luminance in your preferred unit (cd/m², nit, or fL).
  4. Choose the metering constant (default is 12.5, or enter your custom value).
  5. Press calculate, and you’ll see the exposure time in seconds and as a fraction.

For example, if you set an aperture of 5.6, ISO 400, and luminance 500 cd/m², the calculator will give an exposure time of roughly 0.002 seconds or 1/500.

It’s fast, accurate, and easy to use even if you’re just starting photography.

Why You Should Use This Calculator

Manually figuring out exposure time can be tricky. You need to balance aperture, ISO, and light conditions. Our tool simplifies this and avoids mistakes. It’s especially useful for:

  • Low-light photography
  • Action shots with fast-moving subjects
  • Night photography or long exposures

It also helps you experiment with creative effects without guessing.

Final Verdict

The Exposure Time Calculator is a must-have tool for photographers. It saves time, improves accuracy, and makes photography more fun. You don’t need complex formulas or guesswork anymore. Just enter your values, and get the perfect shutter speed instantly.

FAQs

What is a good exposure time for daylight?

Usually, 1/125 to 1/500 of a second works well. But it depends on your aperture and ISO.

Can I use this for video?

Yes. Understanding exposure time helps you set frame rates and motion blur in videos.

What units does the calculator support?

It supports cd/m², nit, and foot-lamberts (fL). It converts all values to a standard unit for calculation.

Do I need to change the K value?

Most of the time, the default 12.5 works. Change it only if your meter or situation requires it.