Depth of field, factors that influence

Depth of field, factors that influence

Have you ever asked me what is the depth of field and what factors influence . As we speak of photography, the depth of field is understood to be photographically speaking. Today I intend to clarify this concept in the best possible way since it affects our photographs. I already wrote an article about depth of field before. Today I return to this topic to expand the information about it.

Let’s begin to clarify concepts about depth of field in photography with a sample photo. Remember, I always like to use a practical example, and, although it may not seem like it, what I like the least is writing.


I made this photo with a camera body reflex Canon Eos Great public, that means that my multiplication factor was 1.6 since my sensor was APS-C. I used a Canon EF lens of 50 F1.8 millimeters. The diaphragm aperture in this particular photo was F 2. The focal distance is evident since only 50 millimeters were available. The ISO sensitivity was set to 100 and the exposure time was 1/640 seconds.


Does the size of the sensor influence the depth of field?

There are nuances regarding the size of the sensor and how it affects the depth of field, it is understood that the size of the sensor does not matter if we balance the focal distance to the subject of our photograph. In other words, imagine that you have a full-format camera and you want to achieve the same depth of field with an APS-C sensor , which would be the sensor that most public bodies reflect, as the APS-C sensor has an image multiplication factor, this directly affects the depth of field since an image taken with a focal length of 18 millimeters in full format has exactly a focal distance of 18 millimeters. If we take the photo with an APS-C sensor, we will always have a multiplication factor to take into account. In Canon large public and semiprofessional bodies (currently up to Canon Eos 7D), the multiplication factor is 1.6, while the sensors of other manufacturers have a different multiplication factor.

So omitting this previous point we could say that the size of the sensor influences the depth of field. However, if we take it into account, the size of the sensor does not influence the depth of field , since actually the size of the sensor only influences the focal distance, increasing it in the case of APS-C sensors and in all those that have a multiplication factor.


The focal distance and its repercussion in the depth of field:

As I mentioned in my previous article about depth of field, the focal distance is the multiplication of the available millimeters of our objective multiplied by the size of the sensor. This means that a 200 millimeter lens will have exactly that focal length in full format while in APS-C format sensors our focal length will be 200 millimeters multiplied by the multiplication factor of our sensor.

We can summarize that the greater the focal distance, the lower the depth of field.


Diaphragm opening and its effect in depth of field:

The diaphragm aperture regulates the amount of light that enters our sensor . A larger opening (smaller F number), more light input and less depth of field. The smaller the opening (larger F number), the greater the depth of field. And this point is impepinable.


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