What Is Exposure in Photography?

Q: What is exposure in photography?

Exposure is the total amount of light reaching the camera sensor when a photo is taken. It determines how bright or dark the resulting image looks. Three settings control exposure: shutter speed, aperture, and ISO. Together they form the exposure triangle.

Q: How do I adjust exposure on iPhone?

Open the Camera app, tap the area you want to focus on, then drag the small sun icon next to the focus box up or down to brighten or darken the shot. iOS 14 and later let you lock exposure compensation by tapping the +/- icon at the top of the Camera app.

Q: What is the exposure triangle?

The exposure triangle is a model showing the relationship between three exposure settings: aperture (size of lens opening), shutter speed (how long the sensor is exposed), and ISO (sensor sensitivity). Changing one usually requires adjusting another to maintain the same overall exposure.

Exposure in photography is the total amount of light reaching the camera sensor when a photo is taken. It determines how bright or dark the resulting image looks. Three settings together control exposure: shutter speed, aperture, and ISO — collectively known as the exposure triangle.

The Three Components of Exposure

Shutter speed: How long the sensor is exposed to light, measured in fractions of a second (1/30, 1/250, 1/2000). Faster shutter freezes motion. Slower shutter blurs motion and lets in more light.
Aperture: The size of the lens opening, measured in f-stops (f/1.4, f/2.8, f/8). Wider apertures (smaller numbers) let in more light and create shallower depth of field.
ISO: The sensor's sensitivity to light. Higher ISO captures more light in dark conditions but introduces noise.

How Exposure Works on iPhone

iPhone uses a fixed aperture (you cannot change it physically) and automatically chooses shutter speed and ISO based on the scene. iOS adjusts everything in real time using its computational photography pipeline. You can override the automatic exposure by tapping a subject in the Camera app, then dragging the small sun icon next to the focus box up or down to brighten or darken the image.

iOS 14 and later let you lock exposure compensation across multiple shots. Tap the chevron at the top of the Camera app, choose the +/- icon, and set a stop value that persists between photos.

Common Exposure Problems

Overexposed: The image is too bright. Highlights are clipped to pure white and detail is lost. Reduce exposure compensation or move to less bright surroundings.
Underexposed: The image is too dark. Shadows lack detail. Increase exposure compensation or use Night mode in low light.
Mixed lighting: Some parts of the scene are too bright while others are too dark. iPhone's HDR and Smart HDR features handle this automatically by combining multiple exposures.

Editing Exposure After the Fact

The Photos app on iPhone lets you adjust exposure, brilliance, highlights, shadows, contrast, and brightness in the Edit menu. ProRAW and RAW files preserve the most flexibility for fixing exposure problems in post-processing because they store the unprocessed sensor data.

Related Terms

Frequently Asked Questions

What is exposure in photography?

The total amount of light reaching the sensor, controlled by shutter speed, aperture, and ISO. It determines how bright or dark the photo looks.

How do I adjust exposure on iPhone?

Tap to focus, then drag the sun icon next to the focus box up or down. iOS 14+ also lets you lock exposure compensation in the camera settings.

What is the exposure triangle?

The relationship between aperture, shutter speed, and ISO. Changing one usually requires adjusting another to maintain the same exposure.

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