Night mode on iPhone cameras turns on automatically in low-light situations, and you can manually adjust or turn it off using on-screen controls. Direct steps (generic, works on iPhone models with Night mode):

• Open the Camera app and frame your shot.
• In low light, a moon icon named Night Mode will appear near the top of the screen (or below the viewfinder on some models). If you don’t see it, the camera may already be using Night mode automatically. The mode is usually enabled automatically when the lighting is dim enough. [web results indicate this behavior across recent iPhone models]
• To manually control it: tap the Night Mode button (moon icon) and use the slider to choose the exposure time (Max extends the capture time). You can select a shorter exposure or turn it off by tapping the moon icon again. Your choice is saved for subsequent shots. [web results mention the icon, slider, and persistence of settings]
• When you’re ready, press the shutter button and keep the iPhone steady to let the longer exposure collect more light. [general guidance associated with Night Mode usage]

Tips for better Night Mode photos:

• Keep the iPhone as steady as possible; use a tripod or rest your device on a stable surface.
• Use the exposure slider to balance brightness and noise; longer exposures can produce brighter images but require steadiness.
• If you’re photographing moving subjects, set a shorter exposure time to reduce motion blur, or use Night Mode with caution.

If you’re using an older iPhone that predates deeper Night Mode controls, Night Mode may be automatic and not manually adjustable. In that case, simply ensure lighting is dim enough for the camera to trigger Night Mode, then hold still and tap the shutter when ready.