When does Nikon d3200 use A S P files, that is, what files are used for taking photos? And why the photos are so dark.

In the first gear, the aperture is automatically exposed first to control the depth of field. If you want to blur the background when taking a portrait, you can control the aperture at the maximum aperture.

S file is a speed-first automatic exposure, which is used to shoot moving subjects and keep them clear. General shutter 1/500- 1/2000 seconds is enough.

The difference between the P gear and the green gear (automatic gear) is that the EV value, white balance and flash are allowed to be adjusted in the P gear, while the green gear is completely controlled by the machine, and all settings cannot be adjusted by itself.

If the photos taken in these files are too dark and the exposure is normal when they are set in the green area, it is likely that the EV value is set incorrectly. There is a small button behind the shutter to mark the sign. When pressed, the status of the electric vehicle can be displayed. If it is -0.3 to -2.0, just dial it to 0.0.