A couple walking down a cobbled city street after dark, sharp from the cap on his head to the stitching on her coat, with a crowd of thirty other people and a moving tram dissolved into soft colour behind them. Nothing in the background is legible. That is the point. The separation was not made in software, and it was not made by cranking the ISO. The standard advice for night street work is to buy the body with the cleanest high ISO and shoot a modest zoom at f/4.

Four dancers in saturated blue and red robes on a lit wooden stage, with everything below the stage edge falling away into an almost black auditorium of heads. The costume is the brightest thing in the frame by a wide margin, and it is the thing the camera’s meter will get wrong. Stage lighting looks generous. There is a lit subject, there is contrast, there is colour. Every part of that is a problem in a different way, and the problems compound: the meter reads the wrong thing, the shutter speed you need is faster than the light supports, and the shutter mode that keeps you welcome in the room introduces artefacts of its own.

Lyon, 15 July 2018, early evening, a few hours after France won the World Cup final. The frame was taken from inside a carriage rolling into the station, through a window covered in water. Two women with tricolour paint on their cheeks and a flag rolled under an arm, a man in a cap on his phone, white bevelled tile, a notice about the Eurexpo access closure running to 31 August.

A white service robot in a moulded gown stands on a red carpet at a hilltop terrace, holding a lit screen out at chest height. A ring light glows amber around one eye socket, a small LED panel burns above its head, and the city behind it is deep into blue hour with the streetlights already on. Two men work the edges of the frame. One in a black tee is checking something in his hands, the other in a suit is watching the screen.

Behind every seamless documentary transition and every establishing shot that opens a news package, there is a crew standing on a balcony in the sun waiting for something to happen. This frame catches two of them working a high vantage point above a dense, sun-bleached city, turning a public overlook into a small production control room. The centrepiece sits on a heavy fluid-head tripod behind an ornate iron railing: a professional video body with an external monitor, a shotgun mic up top, a phone clamped above the screen, and enough audio cabling to discourage any passer-by from asking for a portrait.

Two figures share a photograph and refuse to share anything else. He stands on the left in a black suit, glasses, mid-sentence, addressing someone outside the frame. She stands on the right in a black slip dress, eating from a paper wrapper, eyes down. Running between them is the white vertical edge of a display panel, and that edge does more work than either sitter. The object The panel edge falls near the golden section rather than the middle, which is why the split reads as deliberate instead of careless.

Count the cameras in this frame. Roughly a dozen visible, probably twenty in the group, DSLRs on neck straps and wrist straps and one small compact hanging off a belt loop. Now count how many are being used. One, at the far left, and she is holding it at chest height with her hand over the top plate, not shooting anything. Everyone else is standing on a pavement outside a clothing shop, looking at their phones, looking at their bags, looking at the back of the person in front of them.

This beach frame is a good argument for the 135mm focal length. The woman sitting on the sand holds the eye because she’s the only thing rendered with any real detail. Everything behind her turns into a wash of turquoise and green: umbrellas, chairs, sunbathers, a whole crowded stretch of coastline reduced to shapes and patches of colour. Nothing back there competes with her, and nothing back there had to be moved, cropped out or waited for.

Stand behind a line of photographers pointed at something offshore and you can price the whole row without asking a single question. Two or three big white primes, a handful of black consumer superzooms, at least one lens discontinued before mirrorless existed. One person has a monopod planted in the sand and the rest are holding everything up with their arms. They are all framing the same subject at roughly the same size.

A ring light is the only modifier that puts the light source exactly where your lens is. Everything else about it follows from that one fact, including the things people find surprising about it later. It isn’t a soft box with a hole in it and it isn’t a beauty dish. It’s a light that sits on the optical axis, and on-axis light behaves in a way nothing else does.