How the trade works
Exposure is set by three things: aperture (how wide the lens opens), shutter speed (how long light hits the sensor), and ISO (how much the signal is amplified). On a phone the aperture is usually fixed, so you're left balancing two: shutter and ISO. Make the shutter one stop faster and you halve the light — so you raise ISO one stop to put it back. That's what every row of the table above is: the same total exposure, split differently.
Which pair should you pick?
- Faster shutter + higher ISO — freezes motion (kids, pets, street) but adds noise. Go just fast enough to stop the blur.
- Slower shutter + lower ISO — cleanest image, but any movement (yours or the subject's) smears. Brace the phone or use a tripod.
- Middle ground — for a still subject in decent light, keep ISO low and the shutter fast enough to hand-hold (a rough rule: 1/60s or faster).
What EV tells you
EV (exposure value) is a single number for "how much light" a setting lets in, referenced to ISO 100. Lower EV means a darker scene needs more light; higher EV means a bright scene. It's mostly a sanity check here — the useful part is the equivalence table, which shows your real, on-device options.
FAQ
Does this control my camera?
No — it's a reference calculator. You read the pair you want and dial it into your phone's Pro/manual mode yourself. Nothing is sent anywhere.
My phone has no aperture setting.
That's normal — most phones have a fixed aperture. Leave it at your phone's value (often around f/1.8) and just use the shutter/ISO table.
Why do all rows say "same brightness"?
Because they are equivalent exposures. The point is that many settings give the same brightness — you choose the one whose side effects (motion freeze vs noise) suit the shot.
Reading the table like a photographer
Every row is the same exposure, so the choice between them is entirely about side effects. Sliding toward faster shutter buys you sharpness on moving subjects at the cost of more sensor noise; sliding the other way buys you a cleaner image at the risk of motion blur. Experienced shooters don't hunt for a "correct" row — they decide which risk they can least afford for this particular shot (a running child: freeze it; a still landscape at dusk: go clean and slow) and pick the row that manages that risk, accepting the trade on the other axis.
Why phones lean on ISO and shutter
On a dedicated camera you'd open or close the aperture as a third lever, changing depth of field at the same time. Most phones fix the aperture, so that lever is gone — which is actually why this two-variable table is the right mental model for phone Pro mode. It also explains why phone photos tend toward everything-in-focus: with a small fixed aperture, depth of field is largely decided for you, and your creative control lives in the shutter/ISO balance the table lays out.