Apple iPhone iOS 8.4 - Manual (Page 97)

Chapter 12 Camera 97
Camera settings
Go to Settings > Photos & Camera for camera options, which include:
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iCloud Photo Library, My Photo Stream, and iCloud Photo Sharing
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Burst photos
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Slideshow
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Grid
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HDR
Adjust the volume of the shutter sound with the Ringer and Alerts settings in Settings > Sounds.
Or mute the sound using the Ring/Silent switch. (In some countries, muting is disabled.)