Just use18,55 ordinary 3x zoom lens. 18,55 lens is converted into the full width of 24,82.5, which can take into account the large scene (24 wide angle) and the portrait is not distorted (the minimum distortion is more than 50). If you use a fixed-focus lens, you can't take care of both. If you bring a lot of shots back and forth, you will lose a lot of precious moments, which can't be compensated.