Camera

Virtually any digital camera or smartphone can be used for headstone photography, subject to the following guidelines:

A big optical zoom is strongly recommended. 10x or more is ideal. It avoids having to constantly stretch, reach or kneel for close-up pictures. It also avoids the problem of taking pictures of yourself reflected in polished granite tablets, or being unable to get close enought to a headstone that is inside an enclosure.
Digital zoom only degrades image quality and should not be used.
Remember to steady the camera when zoomed in to avoid image blur, although many modern cameras are equipped with image stabilisation. A single-leg tripod (monopod) is recommended.
Image resolution should be around 3Mp (2048 x 1536 pixels).
A camera with automatic geo-tagging capabilities is strongly recommended. All modern smartphones qualify, although most lack a suitable zoom.
Spare batteries are a must, especially with geo-tagging cameras, which use more power.
Date-stamping of photographs should be disabled.