Creative Aperture – Depth of Field

If Photography is about sharing with the viewer an idea, a concept, a feeling, how can one achieve this in the world we live in today with flashy coloured cars and people walking down the street talking on their cell phone, industrial buildings, etc. All those disturbances can easily violate your exposure, stealing away your subject. Just like when the ISO and Shutter speed aren’t enough to balance our exposure, the Aperture once again come to our rescue! As a matter of fact, the Aperture affect the Depth of Field.

What is the Depth of Field?

The depth of field is the zone that appears sharp before and behind the subject you chose as the point of focus. The very interesting thing is that the depth of field can be more or less deep, and this is affected but the following:

1. The Aperture
2. The Focal Length of the lens
3. The distance between the subject and the lens

In this episode, we are focusing on the Aperture factor.

The rule is simple

The smaller the Aperture value (F-number), the wider the Aperture of the lens, the narrower the Depth of Field. Subsequently, the bigger the Aperture value (F-number), the narrower the Aperture of the lens, the deeper the Depth of Field. Below are the sample exposures I took on St Patrick Day. Note that throughout the shoot, I have used a constant ISO100, my camera set on the Aperture-priority mode (we will see all the mode most DSLR come with in a future episode),  a sturdy tripod and always focus on the Guinness can at all time. F-number between 11 and above are used when a deep Depth of Field is required, like in Landscape Photography, Macro photography due to the close distance between the lens and the subject (we will cover that in a future episode).

F-numbers between 8 and 11 are used when the Depth of field does not matter, all details on the exposure are at the same level ( graffiti on a wall, a band on stage…).

F-numbers between 1.2 and 5.6 are used when a narrow Depth of Field is driving an exposure such as in Portraiture.

As you can see the F1.8 exposure is empowering the Guinness can. This is the reason why a narrow Depth of Field is praised by Portrait Photographers. Understanding the relation between the Aperture and the Depth of Field is crucial in creative Photography. If I had to make an analogy, I would say that the changing your Aperture is to Photography what sacrificing your pawn in chess is. You are bound to do it, but more importantly, you need to know why!