It's a bird

by Vian Esterhuizen

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If you are comparing lenses / cameras with roughly equal field of view then the quantity you want to look at to determine the level of background blur is the diameter of the entrance pupil. This is easily calculated from the spec sheet by dividing the focal length by the f-number. For a 100mm f/2.0 lens the entrance pupil is 100/2 = 50mm wide. A 25mm f/2.0 ...


2

Try a DoF calculator like DoFMaster: http://www.dofmaster.com/dofjs.html Not sure what you mean by "compound lens"—zoom maybe? lens+converter?—but yes, DoF is always inversely proportional to f-stop. DoF is also inversely proportional to magnification. DoF might be inversely proportional to lens focal length if you hold subject distance constant. But if ...


5

No, this is not diffraction. Let's start by recalling how the image is formed by the lens (focused and defocused): Each point of your large aperture lens contributes to just one point of the defocused image: (by the way, this also shows why aperture size affects (de)focus) And what happens if you place an obstacle (your hands) near the lens? Not all ...


2

I think there are two very basic reasons why DoF scales are no longer put on lenses: zoom and autofocus. Zoom lenses would have to have dynamic DoF scales that would change for whatever focal length is set on the lens. While maybe this could be done with, say, eink or lcd displays, it's something that's never really been put on lenses before. But the more ...


3

First, a word about what depth-of-field is and is not: In a way, depth-of-field is an illusion. There is only one plane of focus. Everything in front of or behind the point of focus is out of focus to one degree or another. What we call DoF is the area where things look, to our eyes, like they are in focus. This is based on the ability of the ...


4

Not including a DOF scale can make the lens barrel smaller and allows the use of different focusing mechanisms such as linear motors instead of the traditional helicoid (which is where the DOF scale used to be printed). It is less important to have the scale as you can get instant feedback on what is and isn't in focus with a digital camera, and differences ...


14

The D5300 and D5500 bodies do not have the depth of field preview button. Whether it matters is a personal preference. I never use the DOF preview on my camera (ok, maybe occasionally when shooting macro). With digital you can just shoot and review on the LCD. There are some limitations around how accurate DOF preview is with wider apertures. See these ...



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