Depth of field is the near to far sharpness in your pictures. A picture with shallow depth of field has only the main subject in focus, and everything in front of it and behind it is blurred. The opposite is a picture with deep depth of field, where everything is sharp from right up close […]
Depth of field preview
Usually you view the scene with the camera lens wide open and it only stops down to your chosen aperture the moment you press the shutter button, so it’s hard to judge just how much depth of field the final photo will have. The depth of field preview stops the lens down to the taking aperture, though, so you can judge the effect in the viewfinder or on the LCD display.