Monthly Archives: January 2014

damienfournierco

January 25, 2014

Depth of Fied and Circle of Confusion

The definition of Depth of Field (DoF) from Wikipedia says that it is “the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image“. It relies on the notion of “acceptable sharpness” which is based on a criteria called the ”Circle of Confusion” (CoC). This article explains the essential about the criteria of sharpness and DoF.

A photograph is exactly sharp only on the focus plane, and more or less blur around it. The transition between little blur and definitely blur is gradual, so where do we determine the limit of acceptable sharpness that defines the Depth of Field (DoF)?

dof_coc_gradual_blur2

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damienfournierco

January 18, 2014

Composition Tip – Where to cut off a portrait

I recently received this comment on a portrait that I took :
“But why did you cut off the top of the head ???”
And it sounded more like a criticism than a question.

composition_cutoff_foreheadTo some people it may look weird or unpleasant, but to me it looks just fine, especially because it allows to place the eyes somewhere nearby the 1/3 of the frame. But while I like to cut off the forehead, I would never cut off in the middle of the chin or the hand. So are there any rules to crop a portrait ?

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damienfournierco

January 10, 2014

Introduction to Depth of Field

This article is the first of a series dedicated to the concept of Depth of Field (DoF). It is a technically complex topic that scares many photographers including the experienced ones, and caries many popular misconceptions. The aim of these articles is to explain ‘how to control the DoF in your photographs’ in an understandable, but accurate way.

The articles will explain among other things that :
– DoF is not 1/3 in the front and 2/3 behind the focus point.
– Aperture is not the dominant parameter to control DoF.
– It is possible to make a group shot of 120 people with an aperture of f1.2 and have everyone in focus.
– A blurred background is not the same thing as a shallow DoF.
– It is possible to estimate the DoF at a glance in just a couple of seconds.

dof_limits_guitar_crop

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