![]() ![]() Conversely, the reverse is true – the farther away an object is and focused on, the deeper the DOF. The last element affecting depth of field is the distance of the subject from the lens – you can adjust the DOF by changing that distance.įor example, the closer an object is to the lens (and the focus is set on that object) the shallower the DOF. It’s important to understand this concept and how it affects exposure because it works in tandem with the shutter speed (we’ll discuss this in another section) to establish a given exposure value.īasically, when you change the aperture size one stop, you have to shift the shutter speed one stop in the opposite direction to maintain a consistent exposure… and this change in aperture alters the depth of field (DOF) accordingly. Such that an f/4 on a 50mm has smaller opening than an f/4 on a 200mm, but an equivalent amount of light travels through both lenses to reach the image sensor thus providing the same exposure.Įach movement up the range (say f/2 to f.2.8) reduces the amount of light by one-half, and each movement down the range (say f/11 to f/8) doubles the amount of light passing through the lens. The aperture range identifies the widest to smallest range of lens openings, i.e., f/1.4 (on a super-fast lens) to f/32, with incremental “stops” in between (f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, and f/22).Įach f-number is represents one “stop” of light, a stop is a mathematical equation (which is the focal length of the lens divided by the diameter of the aperture opening) that determines how much light that enters the lens regardless of the length of the lens.
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