Hyperfocal Distance in Digital Photography refers to a distance beyond which all objects in front of the lens can be made into an acceptable focus. It is the sharpness of focus excluding any issue of movement. Previously we said about Hyperfocal Distance in our article on Deep Focus in Digital Photography.
Basics About Hyperfocal Distance in Digital Photography
Hyperfocal Distance can be expressed in two ways :
- The minimum distance at which the subject is in focus, if we focus on infinity.
- Distance focus made on the hyperfocal provides a clear picture of the half that distance to infinity.
The hyperfocal distance is used by photographers to get the maximum depth of field maximum ( in landscape photography, for example) or to simplify the parameter focus when taking a picture, allowing to focus on other aspects of the scene. Determining the hyperfocal distance depends crucially on the perceived sharpness of an image expressed in its formulation by the circle of confusion. Theoretical calculation takes no account of the aberrations of the lens or the resolution of the sensitive surface or visual acuity of the observer of the final image, the latter two having no influence on the point of design.
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Calculation Hyperfocal Distance
The hyperfocal distance (H) is calculated with three parameters according to the formula :
H = {f^2 / Nc} + f
Where,
H = hyperfocal distance
f = is the focal length in mm.
N= is the opening of the diaphragm
c= is the value of the circle of confusion in mm
Or, if we use the Using the diameter of the aperture :
d = f/N —- (i)
H = (f/d) / c — (ii) (d is derived from first equation and notations are same as above plus d is the diameter of the aperture in meters)
The interest here is to have the greatest depth of field, not knowing the exact distance to the subject. A 35mm SLR equipped with a f8 lens, the hyperfocal is about 5 m and dividing by 2, the minimum distance is about 2.5 m. The interest of the hyperfocal is for the photographer who uses the manual focus.
