Choose whether exposure locks when the shutter-release button is pressed.
| 
                                                          Option  | 
                                                      
                                                          Description  | 
                                                   |
|---|---|---|
| 
                                                          O  | 
                                                      
                                                          []  | 
                                                      
                                                          Pressing the shutter-release button halfway locks exposure.  | 
                                                   
| 
                                                          P  | 
                                                      
                                                          []  | 
                                                      
                                                          Exposure only locks while the shutter-release button is pressed all the way down.  | 
                                                   
| 
                                                          []  | 
                                                      
                                                          Pressing the shutter-release button does not lock exposure.  | 
                                                   |
