Four cameras, and the one you will actually use
Most phones sold on a camera count give you one lens worth using and a short list of sensors that exist to lengthen the list. Here is how to tell which is which before you buy.
A phone advertised with four cameras rarely has four useful ones. It usually has one main sensor that takes almost every photograph you will keep, one wide lens that is genuinely different, and one or two small sensors whose job is to appear in the specification. Knowing which is which changes what you should compare, because two phones with the same camera count can be a long way apart, and two phones with different counts can be identical where it matters. The test is simple once you know what to look for, and it takes about a minute on any product page.
Count the sensors that could carry a photograph alone
Only some of the lenses on a phone can produce a usable picture by themselves. The main sensor always can. A wide-angle lens can, and gives you a frame the main one physically cannot reach. A real telephoto can, and brings distance closer without cropping. Everything else on a typical list — a small macro, a depth sensor, a monochrome helper — assists in software or covers one narrow situation badly. A phone with a main and a wide has two cameras. A phone with a main, a wide and two small helpers also has two, and is sold as having four.
- Main, wide and telephoto can each carry a photograph on their own.
- A low-resolution macro or depth sensor is a specification, not a camera.
Stabilisation matters more than resolution
Sharpness in anything other than bright daylight is decided by whether the camera can hold still. Optical stabilisation physically counteracts hand movement, which lets the shutter stay open longer without smearing. Electronic stabilisation crops and shifts the frame instead, which helps video and does rather less for a still photograph. Between two phones with the same resolution, the one with optical stabilisation on the main sensor will give you more keepers indoors and at dusk, and that is most of the photography most people do.
Zoom is either real or it is a crop
A telephoto lens has its own glass at a longer focal length, so it genuinely reaches further. Digital zoom crops the main sensor and enlarges what is left, which throws away detail the moment you pass the sensor resolution. Many phones present both under one slider, so the first part of the range is real and the rest is a crop. The honest way to judge is to take the same photograph at the maximum advertised zoom and look at it at full size, rather than on the phone screen where everything looks sharp.
The processing decides more than the sensor
Modern phone photographs are assembled, not captured. The camera takes several frames at different exposures and merges them, correcting colour and noise on the way. Two phones with the same sensor can produce visibly different pictures because they make different choices here: one brightens faces, one keeps shadows dark, one sharpens aggressively. This is also why a sensor comparison in a specification table predicts so little. Look at photographs taken on the phone, in the light you shoot in, rather than at the number next to the lens.
Video has its own answer
A phone can be good at photographs and mediocre at video, because video uses a different path. The things to check are whether stabilisation stays on at the resolution you want, whether the phone can switch lenses while recording without a jump, and how long it will record before heat forces it to stop. That last one is rarely published and matters most, because a phone that stops filming after a few minutes is not a video phone, however good the first few minutes look.
What to try, in order
- Count only the lenses that could carry a photograph alone: main, wide and true telephoto.
- Check whether the main sensor has optical stabilisation, not only electronic.
- Find where the real zoom ends and the crop begins, and judge the picture at full size.
- Look at sample photographs taken in dim light, which is where processing choices show.
- For video, check whether stabilisation survives at your chosen resolution and how long it records before stopping.
What to take from this
The camera count on a box is a marketing figure, and it can be inflated with sensors nobody uses. What you will actually use is one main lens, perhaps a wide, and perhaps a telephoto if the phone has a real one. Judge those, check for optical stabilisation, look at pictures rather than specifications, and the decision becomes much simpler than the box wants it to be.
Common questions
Do more megapixels give sharper photographs?
Only in good light, and only if you crop. A higher count divides the same sensor area into smaller collectors, so each gathers less light. In a dim room the larger collectors win. Most high-count phones quietly combine neighbouring pixels in low light for exactly this reason.
Is a macro camera worth having?
Rarely, in the form usually fitted. A low-resolution macro with no autofocus produces soft pictures at an awkward distance. A main sensor that focuses closely, or a wide lens that doubles as a macro, is more useful than a dedicated sensor added to raise the count.
Why do my photographs look worse than the samples on the box?
Because the samples were taken in ideal light, often on a tripod, and sometimes on a different variant of the model. Look for pictures taken by owners in ordinary rooms. If a phone only ever appears in bright sunshine, that is itself information.
