Zoom lenses are not used in view camera photography, as there is no need for rapid and continuous change of focal length with static subjects, and the price, size, weight, and complexity would be excessive. Some lenses are "convertible": the front or rear element only, or both elements, may be used, giving three different focal lengths, though the quality of the single elements is not as good at larger apertures as the combination. These are popular with field photographers who can save weight by carrying one convertible lens rather than two or three lenses of different focal lengths.