Do you need a camera, or is your phone already enough?

Start with the concession, because it is a large one. For everyday pictures in ordinary light, a current phone beats most cameras in this catalogue at the thing that matters most to most people: producing a finished, pleasant image without you doing anything at all.

It does that with computation rather than optics. It captures a burst of frames before you press the button, aligns them and averages the noise away. It maps a scene whose bright and dark parts are many stops apart into something a screen can show, so the sky keeps its colour and the face is not a silhouette. It segments the picture into sky, skin and foliage and treats each differently. A camera does none of this by default, and its file straight out of the box looks flat beside a phone.

And it is in your pocket. That is not a small advantage; it is the largest one. A camera at home has no dynamic range, no autofocus and no lens.

• Snapshots of people, food and rooms in daylight or decent indoor light.
• High-contrast scenes — a backlit face, an interior with a bright window — where multi-frame HDR does in one press what a camera asks you to bracket and merge.
• Anything you want to send to somebody within a minute.
• Video of your own life, where stabilisation and a microphone that ignores wind matter more than a sensor.
• Documents, receipts, whiteboards and the shelf you want to remember when you get to the shop.

Computation cannot manufacture photons and it cannot move a lens further from a sensor. Four things stay firmly on the camera side, and together they are the whole case for buying one.

1. 1

   Light that is genuinely low

   Not a lit restaurant — a candlelit room, a church interior, a stage, the night sky. A full frame sensor measures 36 by 24 mm, roughly ten times the area of a large phone sensor and considerably more than a small one: three stops and upwards, before the lens is considered. Frame stacking closes some of that until the subject moves, and then it stops closing anything. If your indoor winter pictures of your children are smeared, this is the reason.

2. 2

   Shallow depth of field at a real distance

   Portrait mode is a depth map with a blur applied to it, and it is good on head and shoulders against a clean background. It fails on hair, on glasses, on a chain-link fence and on anything more than a few metres away, because there is no genuine defocus underneath it. A 90 mm-equivalent f/1.8 lens — the OM System 45mm f/1.8 is €280 — does it optically, at any distance, with no edges to get wrong. On Micro Four Thirds that renders like f/3.6 on full frame, still far beyond what a phone lens produces optically.

3. 3

   Reach

   A phone tops out at a few times its main lens before it starts cropping into the file. Lenses in this catalogue reach 914 mm full-frame-equivalent. If you want a bird that fills the frame, a player on the far touchline, or the moon as something other than a white dot, there is no software route to it. This is the most common reason a phone owner becomes a camera owner. The wildlife answers under €1,000 are where it usually starts.

4. 4

   Moving subjects, tracked, in bursts

   Continuous autofocus that holds an eye across a sequence, at frame rates running to 40 fps here, with a buffer deep enough to keep them, is a camera thing. Phones shoot bursts, but they do not track a swimmer through twenty frames and keep her sharp. Sport, wildlife, dogs and toddlers are camera work, and this is the capability you are actually buying.

There is a quieter fifth reason: raw latitude. A camera raw file holds more recoverable highlight and shadow detail than a phone raw, and its noise stays cleaner when you push it. That matters if you print large or edit hard. If you post to a screen and never edit, it does not matter at all, and you should not pay for it.

Between a phone and a system camera sits the large-sensor compact: a fixed lens, a sensor several times the area of a phone, a body that still goes in a coat pocket. This catalogue holds 9 compacts and 7 cameras with a small one-inch-class sensor, and the cheapest small-sensor camera in it is €450.

Be precise about what that sensor is. One inch describes nothing: it measures 13.2 by 8.8 mm, about 116 square millimetres against 864 for full frame, which puts it just under three stops behind. Against phones the gap has narrowed a long way — a flagship phone sensor can be more than half that area, so the raw light advantage is well under a stop, and the phone spends it on computation you do not get.

So do not buy one expecting full frame files, and do not expect it to beat your phone on a daylight snapshot. Buy it for what the phone cannot do at all: a real zoom, real controls under your fingers, a shutter that fires when you press it, and a file that survives editing. If weight is the constraint but you want interchangeable lenses, Micro Four Thirds is the other answer — €700 at the cheapest here — and sensor size explained sets out what that saves and what it costs.

A different question, asked by people who already own a camera: is a second one worth it? Usually not. The honest test is whether you can name the specific picture the first one cannot take.

• A backup at a paid job is a real reason. If you are being paid and the day cannot be repeated, you need a second body and it does not have to be a good one.
• A different sensor size for a different purpose is a real reason: a light Micro Four Thirds kit for travel alongside a full frame kit for work.
• A camera you will genuinely carry every day, when the main one is too big to leave the house with, is a real reason. This is what large-sensor compacts exist for.
• A newer body of the same size, same mount and same sensor size is usually not a reason. Sell the old one or put the money into glass — the lens finder will show you what that buys.

The one exception worth naming is autofocus. Subject detection improved enough across recent generations that a photographer of moving subjects can genuinely be gated by an older body. If you shoot sport or wildlife and your keeper rate is the complaint, that is a real upgrade, and the one case where a new body beats a new lens.

You already own a camera

Buy a lens. It is the highest return in photography per euro and it costs less than a body. Fast primes start at €220 for the Canon RF 50mm f/1.8, 250 for the Sony FE 50mm f/1.8 and 280 for the Nikon Z 40mm f/2, against a median lens price of 950 in this catalogue. If the complaint is that your pictures look ordinary, a prime two or three stops faster than your kit zoom fixes more of it than any body will.

You own nothing but a phone

Then the answer is often nothing, for now. Spend a month noticing what your phone cannot do and write the failures down. If the list says dark, or far away, or moving, you have a camera-shaped problem and how to choose a camera will narrow it to a shortlist in five questions. If the list says the composition was boring, a camera will not fix that, and neither will anything else you can buy.