Nikon D750 Product Manual - Page 166

A Minimum Shutter Speed Auto shutter-speed selection can be fine-tuned by highlighting Auto and pressing 2: for example, values faster than those usually selected automatically can be used with telephoto lenses to reduce blur. Note, however, that Auto functions only with CPU lenses; if a non-CPU lens is used without lens data, minimum shutter speed is fixed at 1/30 s. Shutter speeds may drop below the selected minimum if optimum exposure can not be achieved at the ISO sensitivity chosen for Maximum sensitivity. A Auto ISO Sensitivity Control Noise (randomly-spaced bright pixels, fog, or lines) is more likely at higher sensitivities. Use the High ISO NR option in the shooting menus to reduce noise (see page 317). When a flash is used, minimum shutter speed will be set to the value selected for Minimum shutter speed unless this value is faster than Custom Setting e1 (Flash sync speed, 0 345) or slower than Custom Setting e2 (Flash shutter speed, 0 346), in which case the value selected for Custom Setting e2 will be used instead. Note that ISO sensitivity may be raised automatically when auto ISO sensitivity control is used in combination with slow sync flash modes (available with the built-in flash and the optional flash units listed on page 433), possibly preventing the camera from selecting slow shutter speeds. A Enabling and Disabling Auto ISO Senstivity Control You can turn auto ISO sensitivity control on or off by pressing the W (S) button and rotating the sub-command dial. ISO AUTO is displayed when auto ISO sensitivity control is on. 138