What aperture for your Harley-Davidson – Part 3

In Part 1 I rambled about different types of cameras and the importance of the sensor’s physical size, in Part 2 of this series I wrote about zoom lenses and the importance of selecting the right focal length. In this Part 3 its all about the light hitting the CCD, and how it is controlled by the shutter speed and the all important aperture.

Although we all use most of the time the so called program mode, where all settings are controlled by the camera automatically, most cameras let you individually select and prioritize either the shutter speed or the aperture.

I like the select the aperture, and let the shutter speed be a automatic calculated as result of the light conditions of the moment. But: let not drop you shutter speed too low. A rough guide is that the slowest shutter speed that can be used easily without much blur due to camera shake is a speed numerically closest to the lens focal length. So a 50mm focal length, do not let the speed drop below 1/60 sec, with a 400mm tele it quickly goes up to 1/400 sec.

But lets take a closer look at the much more important aperture:

I will not bore you with technical explanations of what the aperture is and how it is calculated, just this: its a controllable hole that lets more or less light through the lens.

A small f number, like f/1.4, is a big hole (large aperture), a large f number, like f/16, is a very small hole (small aperture).

This f-selection has some important implications:

  • big f number (f/16)means slow speeds (careful here if your object is moving!)
  • small f number (F/1.4) means fast speeds are possible

but more important:

A larger aperture (small f-number, e.g. f/1.4) has a shallow depth of field. Anything behind or in front of the main focus point will appear blurred. A smaller aperture (larger f-number, e.g. f/16) has a greater depth of field, so objects within a certain range behind or in front of the main focus point will also appear sharp. And this is a very  important artistic tool.

This first picture is taken at f16…

it looks a bit flat, 2-dimensional, but now I open the lens to f1.4..

The aperture changes the focus of the picture, makes it appear 3-dimensional, and if everything except the bike is blurred, it puts the bike right at the center of attention.

Some lenses display the depth of field, and the distances that will be blurred

Specially when you try to show details, or faces, a blurred background is very helpful, and I suggest to select to large aperture (small f number).

above picture taken at f/1.4, lower one at f/16

As we all use digital cameras, with no worries about film cost and prints, try it out, play with the settings, check the results, and a new dimension of artistic expression will open to you. You do not need a very expensive high end DSLR, a smaller camera with a decent lens will do the trick.

And if your camera has no Aperture priority program, or you are just snapping away without paying attention to the aperture… fake it.

Like I did in this picture, where the background was blurred in post-production using Photoshop…

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