<Li> <P> 210 mm </P> </Li> <P> The above photos were taken using a 35 mm camera, using lenses of the given focal lengths . </P> <P> The photographer often moves to keep the same image size on the film for a particular object . Observe in the comparison images below that although the foreground object remains the same size, the background changes size; thus, perspective is dependent on the distance between the photographer and the subject . The longer focus lenses compress the perception of depth, and the shorter focus exaggerate it . This effect is also used for dolly zooms . The perspective of the so - called normal lens, 50 mm focal length for 35 mm film format, is conventionally regarded as a "correct" perspective, though a longer lens is usually preferred for a more pleasing perspective for portraits . </P> <Ul> <Li> <P> 28 mm </P> </Li> <Li> <P> 50 mm </P> </Li> <Li> <P> 135 mm </P> </Li> </Ul>

Characteristics of long lenses above 120mm on a dslr camera