The depth of field in photography
If we have the representation in three dimensions of a scene the depth of field in photography is understood as the part of the image sharp or focused. If we have a wide depth of field it will mean that the part of the image that will appear focused from the first plane to infinity will be remarkable. On the other hand, if we say that a photograph has a shallow depth of field, we are referring to the fact that, except for the distance in focus, the rest of the photo has a lens blur. As I said in some other occasion, photography brings together a number of rules and laws to know. In the same way I have also published the opinion that the rules and regulations in photography can be omitted on purpose if our search for the image requires it.
Photography with a very shallow depth of field , taken with a Canon Eos large public reflex camera and a Canon 50 mm F1.8 II lens. Diaphragm aperture F1.8, exposure time 1/2000 seconds and Iso 100 sensitivity, taken in summer 2009 near Hotel Vela de Barcelona .
Use of depth of field:
There are photographic commands that reiterate the use of depth of field in one direction or another, I recommend you look for information about the depth of field to make some types of photographs. Landscapes, architectural photography, portraits … You will find a myriad of contradictory recommendations if the source of information is different and the subject itself, the depth of field in photography.
Photographic laws and depth of field:
My entry today is as ambiguous as ever and does not intend to position itself in any of the photographic laws regarding the depth of field. It does not pretend to be a professor since I am not an “Awarded photographer” nor is it my intention. My goal today is to make known to those who do not know what factors influence depth of field .
Factors that influence the depth of field in photography:
There are 4 factors that influence the depth of field in photography, the sum of the 4 increases or decreases the depth of field perceived by our sight. The depth of field only exists in a reproduction, it is not an intrinsic property of an objective since it depends on different combinable values that could modify it. These are the 4 factors that influence the depth of field:
The focal distance in photography is the multiplication of the millimeters of the objective that we use for the factor of multiplication of the sensor. To facilitate the understanding of this concept, a professional high-end reflex camera usually has a factor of 1. This makes us call them “full-frame”. A semiprofessional reflex camera body or for the general public has a multiplication factor added to the millimeters of our objective. In this way, a 250-millimeter lens mounted on a sensor with a 1.6 multiplication factor converts it into a 400-millimeter one. Or what is the same, has a focal distance of 400 millimeters. In a summarized and generalized way we can say that the greater the focal distance we will have, the less depth of field.
The diaphragm is the mechanism that allows light to enter the sensor of our reflex camera. In automatic modes it is regulated automatically while in semiautomatic modes it is possible to regulate it and in manual mode we can regulate it completely at our whim. It is identified in our team as the value that is behind the F that indicates the screen or the dial. The lower the F number (diaphragm), the greater the light input on the sensor is, in reverse, the higher the F number in our equipment, the lower the light input to the sensor of our camera. It can be summarized and generalized that at a lower F number, less depth of field.