01 / TIME
Shutter speed
How long you collect light.
1/1000 second is a very short exposure. 1/15 second is much longer. While the sensor collects light, anything that moves can leave a trail.
- Faster · 1/1000 s
- Freezes movement, but collects less light.
- Slower · 1/15 s
- Collects more light, but movement blurs. Even your hands can move the camera.
Try this ↙ Move toward 1/15 s. Watch the cyclist blur while the buildings stay still.
On your iPhone Open Camera Controls → Shutter Speed. Stabilization helps with hand shake; it cannot freeze a moving person. [1]
02 / OPENING
Aperture
The opening light passes through.
An f-number is focal length divided by the opening’s diameter. A smaller number means a wider opening. Think of a wide doorway letting more light in.
- Wide · f/1.48
- More light and a shallower zone of sharpness.
- Narrow · f/4
- Less light and a deeper zone of sharpness. With shutter and ISO fixed, f/4 is about 2.9 stops darker than f/1.48.
Try this ↙ Keep the flowers in focus. Close the aperture and watch the houses become clearer.
On your iPhone The 18 Pro’s Main camera has f/1.48, f/1.8, f/2.8 and f/4 settings. Portrait Depth Control instead simulates blur with processing. Small phone sensors have more depth of field than large cameras at the same f-number and framing. [1, 2]
03 / SIGNAL
ISO
How the captured signal is scaled.
Raising ISO makes the rendered image brighter at the same aperture and shutter speed. It does not bring more light into the sensor.
- Low · ISO 100
- Useful when there is enough light. Usually offers more highlight headroom.
- High · ISO 3200
- Useful when a fast shutter matters in low light. Low-light photos often look grainier because fewer photons were captured; ISO alone is not the whole cause.
Try this ↙ Increase ISO. In this equal-brightness example, the simulated camera shortens the shutter to compensate: less light, more visible noise.
On your iPhone Auto ISO is a useful default. For direct ISO control, use a camera app that exposes it; Apple’s Pro tools guide lists aperture, shutter and white balance. Prefer a sharp, noisy photo to an accidentally blurred one. [1, 3]
04 / THE BALANCING ACT
Exposure
Three controls. Different tradeoffs.
Aperture and shutter determine the light captured. ISO affects how bright that capture is rendered. The same brightness can come from very different combinations.
- One stop = twice or half
- 1/250 → 1/125 s doubles captured light. ISO 100 → 200 doubles the nominal brightness. f/2.8 → f/4 roughly halves the light.
- Read the histogram
- Left = dark pixels; right = bright pixels. Piling up against an edge can mean lost detail. A bright or dark scene does not need a centered histogram.
Try this ↙ Start at f/2.8, 1/250 s, ISO 100. Change to 1/500 s, then ISO 200. Brightness returns; motion looks sharper.
On your iPhone Exposure compensation asks auto exposure for a brighter (+EV) or darker (−EV) result. It is different from manually fixing all three settings. Computational HDR may combine several captures. [3, 4]
05 / COLOR
White balance
Tell the camera what neutral looks like.
A white wall looks orange under warm bulbs and blue in shade. White balance compensates for the light’s color so neutral objects look neutral again.
- Lower setting · 3200 K
- Compensates for warm indoor light by cooling the image.
- Higher setting · 7500 K
- Compensates for blue shade by warming the image. Tint is a separate green–magenta correction.
Try this ↙ This scene is lit by 5500 K daylight. Match it for neutral whites, then deliberately make the scene cooler or warmer.
On your iPhone Camera Controls → White Balance offers manual choices. This Kelvin slider teaches the principle; it does not reproduce the phone’s exact interface. Mixed lighting may need a compromise. [1, 5]
06 / FRAMING
Focal length
How much of the world fits in the frame.
Short focal lengths give a wide view. Long ones give a narrow view and make distant details fill more of the image. Phone specs use 35 mm equivalent focal lengths so cameras can be compared.
- Wide · 13–24 mm equivalent
- More surroundings. Useful for buildings, interiors and environmental portraits.
- Long · 100–200 mm equivalent
- A tighter frame. Useful for distant details. Camera movement becomes more noticeable.
Try this ↙ Zoom in from the same position. Framing changes, but perspective does not. The “compressed” look comes from moving farther away to keep your subject the same size.
On your iPhone 13 mm, 24 mm and 100 mm correspond to Ultra Wide, Main and Telephoto. The 48 mm and 200 mm views use sensor crops, marketed as “optical-quality.” They are not extra lenses. [2, 6]
07 / ATTENTION
Focus & depth of field
Choose what deserves to be sharp.
Focus sets the distance of greatest sharpness. Depth of field is the zone around that distance that looks acceptably sharp. They are related, but different.
- Focus distance
- Switch between the nearby flowers and the distant houses. Autofocus chooses this for you; tapping a subject lets you choose.
- Depth of field
- Aperture, subject distance, focal length, sensor size and viewing conditions affect perceived sharpness. Getting close can make background blur more obvious.
Try this ↙ Focus on the flowers, then the houses. Watch the sharp plane move through the scene.
On your iPhone Tap your subject to focus; touch and hold to lock focus and exposure. Portrait mode uses a depth estimate to add blur, so inspect fine edges such as hair. [4, 6]