The Aiguille du Midi terrace at 3,842 metres

The cable car from the middle of Chamonix climbs to 3,842 metres in two stages and puts you on the Aiguille du Midi, a granite spike with terraces, a bridge and a viewing platform built onto it. From up there Mont Blanc sits directly opposite across the Vallée Blanche, the Grandes Jorasses close the valley to the east, and on a clear day the Matterhorn and Monte Rosa stand on the horizon.

It is the most dramatic accessible frame in the Alps and it is also the most constrained. Space on the terraces is limited and shared, the light is extremely hard at altitude, and there is snow and steel in the same frame — expose for the snow and work with the couple against the sky rather than against the white. Early slots give softer light and thinner crowds; the north-facing terraces stay in shadow and give clean, even light all day.

Weather decides everything here, and it decides it at short notice. The lift closes for wind, ice and maintenance, and it does not run at all during the annual maintenance period — check the day's operating status before travelling up, and have a valley plan for when it is shut. Clear mornings in winter and early autumn give the sharpest air; summer afternoons build cloud on the summits from about midday.

Practical and non-negotiable: it is nearly four thousand metres, and people feel it. Altitude sickness is common, the air is thin, movement is slow, and the temperature is often twenty degrees below the valley — warm layers, sun cream and sunglasses even in July, and no long posing sessions. Anyone with heart or breathing problems should treat this as a medical question, not a photographic one. Bare shoulders and thin dresses at that altitude are a two-minute proposition at most.