Since 1864, photographs have been admissible in evidence. Photographs can be introduced as evidence of what they depict. For example, in a murder trial, photographs may be introduced as evidence of the position and state that the deceased's body was in when it was found.
In order for a photograph to be admitted in evidence, it is first necessary to prove its authenticity. The photographer must prove that he or she took the photograph and the person who has developed the photograph must also give a statement that the negatives were untouched.
For a photograph to be admitted in evidence, the person who took the photograph does not need to be a professional photographer. For example, in a civil case, photographs that you have taken of damage done to your car in a road traffic accident will be admissible (as long as you are available to give evidence in court about when and how you took them).