1. Self-timer : First, pull down the lever and depress the shutter button to work it.
2. Preview button : Because generally, in the viewfinder shows the image at the full aperture, it enables to check the resulting image by depressing the button.
3. Lens release button : With depressing this button, turn the lens counterclockwise and take off the lens.
4. Flash sync contact : M sync is the upper side and X sync is downside.