You may have wondered "How do pros make those wonderful landscapes where everything seems to be in focus?" Well, it is not merely by closing down the aperture of superb wide angle lenses. They maximize DOF (depth of field), the region of acceptable sharpness, by focusing at the hyperfocal distance. A simple function of lens focal length, aperture and the diameter of the Circle of Confusion (CoC).
The wider the angle of a lens, the shorter its focal length and deeper depth of field. So, as an example, an 18mm lens will have deeper (longer) depth of field than a 105mm. Also, the smaller the aperture you use the bigger the depth of field; i.e. in any given focal length lens, one gets more depth of field with it at f/16 than at f/4, for example. You may want to check our articles on the subject of DOF.
The "Circle of Confusion" has nothing to do with other camera brand users. It is the largest on-film or on-sensor circle that you can see as a well defined point on an 8×10 print at arms length; that is, when viewed at from a "normal" viewing distance of 2 to 3 feet. Anything larger is seen as a small circle, not a point and is therefore perceived as out of focus. For 35mm film and FX format the diameter of such circle is 0.025mm. Often rounded to 0.03, the exact number used here is 0.02501. For the Nikon DX (APS-C) digital sensor format, the number used here is 0.0200.
The calculator in the next page allows for you to use any CoC of your choice, via a drop down menu.
These two sample images were shot at f/16. The one on top was made focusing at infinity, the image below was produced with the lens focused at its Hyperfocal Distance.
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