Why stained glass defeats most cameras

A sunny window can be a hundred times brighter than the stone surrounding it. Your camera has to choose one exposure for the whole scene, and it nearly always chooses the average — which means the glass turns into a glowing white rectangle while the interior around it stays murky. The trick is to stop thinking of the window as part of the building and start treating it as the subject. Expose for the glass itself, and let the columns, pews and shadows fall where they may. A slightly dark church interior with a beautifully detailed window is far more satisfying than a well-lit nave with a blown-out hole in the wall.

Meter for the glass, not the pews

If your camera offers spot metering, use it and take a reading from a mid-bright area of the glass — not the brightest white highlight, which will drag the whole exposure down. Evaluative or matrix metering will be fooled by large areas of shadow, so switch to manual or dial in negative exposure compensation of around one to one and a half stops as a starting point.

Then check the histogram. The brightest highlights should sit just inside the right-hand edge, without a spike climbing up the wall — that spike means clipped pixels and lost colour. If your camera shows blinkies or zebras, they are your best friend here.

• Bracket in three frames at one-stop intervals if you are unsure, then choose or blend later.
• Pale yellows and whites clip first, so watch the top of the window especially.
• Underexposure is safer than overexposure: shadow detail can often be lifted, blown highlights cannot be recovered.
• Shoot raw if you can — it gives you roughly a stop of extra headroom at the bright end.

Keep the colours true

Stained glass is a colour accuracy problem as much as an exposure one. Mixed lighting is the usual culprit: daylight through the window, tungsten floodlighting on the walls, candles near the altar, or a sodium street lamp leaking through the west door. Auto white balance will drift unpredictably from frame to frame, which makes a set of images look muddled.

Set daylight white balance manually — around 5500K — as a consistent starting point, and fine-tune afterwards. A thick medieval quarry or a Victorian ruby panel will often cast a greenish or magenta tint on nearby stone, which is the glass doing its job, not a white balance error; correct it locally rather than across the whole image. If you are recording glass as a record rather than an atmosphere piece, resist the temptation to warm everything up. The best compliment a photograph of a window can receive is that the colour looks exactly like it does on a dull Tuesday in February.

Steady support, and what the rules allow

Long exposures are the easiest route to detail. A tripod lets you use a low ISO and an aperture around f/8, where most lenses are sharpest, without worrying about shutter speed. Do check first, though: many cathedrals and larger churches restrict tripods, especially during services or when a party is being shown round, and some ask you to buy a photography permit at the welcome desk.

• A compact tripod, a monopod or a beanbag resting on a pew can be enough. Ask before using any of them.
• Where tripods are not allowed, raise the ISO rather than dropping the shutter speed below about 1/60 second handheld.
• Switch on image stabilisation for handheld work and off when the camera is on a tripod.
• Use the self-timer or a remote release — pressing the button shakes the camera more than you think.

Composition and the details that repay patience

Step back and the window becomes part of the architecture; move in and it becomes a painting. A short telephoto is ideal for isolating single panels, and it also lets you photograph glass from further away, which flattens perspective and reduces the converging verticals you get from standing directly underneath.

Keep the back of the camera parallel to the glass when you want a faithful record, and tilt only when you want drama. Look beyond the obvious: the tracery, the leading between quarries, the small figures in the borders, a maker's signature in the corner. Reflections of your own silhouette, or of a bright window behind you, are a common spoiler — move a step to one side and they usually vanish. A lens hood held against the glass, or a coat draped over your head, does the same job.

Being a respectful visitor

These are working buildings and places of prayer before they are photographic locations. Never use flash — it is distracting, and repeated bursts are not kind to historic glass or furnishings. Avoid wandering into roped-off areas, and keep bags and tripod feet away from tombs, brasses and ledges where they can scratch or topple something. If a service is beginning, put the camera down and stay if you wish, or slip out quietly.

Ask the welcomers or the verger what is and is not permitted; they are usually delighted that someone cares about the glass and will often point you towards the best-lit window of the day. Buy something from the shop or leave a donation. And take your time — the light through a south transept window changes hour by hour, and the best photograph is often the one you waited for.