Wedding photography is somewhat unusual in that the nature of a typical wedding puts a photographer under unique pressures. A wedding may be the most important event in the lives of the couple concerned, and they are unlikely to accept without complaint any failure on the part of their photographer. Should a camera fail, or the photographer make some fundamental mistake, legal action may follow. The wedding cannot be repeated although subsequent "staged" weddings have been organized to obtain photographs lost on the wedding day. Even in these unfortunate circumstances, the bride and groom are unlikely to view their wedding album in quite the same way. The pictures will always be of a mock event rather than their real wedding.
With all this in mind, a wedding photographer must be properly prepared. A basic minimum requirement is the availability of a second camera should the principal camera fail in some way. Many wedding photographers equip themselves with two identical cameras and may carry both at the same time. The two camera bodies are fitted with different lenses, which saves changing lenses on the fly. Should one camera fail, the other is available to continue with the photography.
Professional cameras may provide for images to be written simultaneously on to two memory cards. This provides a degree of protection against memory card failure but obviously involves the use of twice the number of memory cards. Other photographers carry facilities for downloading images during the wedding - perhaps between the ceremony and the wedding breakfast. This approach also guarantees the security of the earlier images should a drink be spilled over the camera at the reception.
Security of images is perhaps the most important consideration for a wedding photographer, but it is also vital to have good-quality cameras and lenses. Choice of lenses varies according to a particular photographer's style and the nature of the wedding, but a fast (minimum f/2.8) 80 - 200mm zoom lens is reasonably standard. A second camera might then be fitted with a fast wide-angle zoom lens such as an f/2 18 - 35mm optic.
Other essential items of equipment include a good-quality warm or half-warm reflector (such as the folding Lastolite type), a powerful flashgun and perhaps a tripod. The tripod can be useful at the wedding breakfast where light levels are likely to be low, but can also be used to establish the photographer's presence, and prime position, when groups are being photographed.
There are of course many other items a photographer may wish to have available at a wedding. These are dependent upon style and circumstances, but might include white umbrellas for use by the bridal party in the event of significant rainfall, and a complete studio flash setup to make all photography possible indoors.