Weekly Photo Challenge: Focus


Great photography is about depth of feeling, not depth of field. – Peter Adams

Peter Adams may be right but changing the Depth of Field can be quite useful in some cases; sometimes it may be desirable to have the entire image sharp, in which case large DOF is appropriate.

Take Your Litter Home

In other cases, a small DOF may be more effective, emphasizing the subject while de-emphasizing the foreground and background.

Spring Buds

Depth of Field can be altered by changing the Aperture in your camera.  Here’s the technical bit;

Reducing the aperture size increases the depth of field, which describes the extent to which subject matter lying closer than or farther from the actual plane of focus appears to be in focus. In general, the smaller the aperture (the larger the number), the greater the distance from the plane of focus the subject matter may be while still appearing in focus.

Aperture_diagram.svg

This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. Attribution: Cbuckley at the English language Wikipedia

So at f4 the DOF will be very small, at f22 the DOF will be large. To show you this I’ve conducted a little experiment, photographing the same scene several times whilst changing the the aperture from f4 to f22.

For this experiment I’ve drafted in Edna and Mabel to act as subjects. Mabel will be in front and throughout the sequence of photographs I will maintain the focus point of my camera on her face. To avoid camera movement it’s mounted on a tripod.

Weekly Photo Challenge: Focus

In the photograph above the aperture is set at f4. As you can see, Edna, who is in the background is out of focus.

14a Focus

Now the aperture is f8, notice how Edna is starting to come into focus. Her features are much more clearer, you can even see her pudgy little nose.

14b-Focus

At f22 the photograph is in sharp focus from front to back including the fence behind Edna. In other words at f22 I have a large Depth of Field.

Every time someone tells me how sharp my photos are, I assume that it isn’t a very interesting photograph. If it was, they would have more to say. – Anonymous

On a practical note for most of my landscape photographs I tend to use f8,  f11 or f16, very rarely do I use f22. There’s a reason for this. If you look at the aperture diagram you can see that the higher the aperture number the smaller the whole is. In combination with variations of shutter speed, that hole controls the light reaching the sensor on my camera. Typically, a fast shutter will require a larger aperture to ensure sufficient light exposure, and a slow shutter will require a smaller aperture to avoid excessive exposure. So If I set the aperture to f22 I would need to have a slow shutter speed, which in turn means I could end up having blur due movement; me holding the camera, the wind moving trees or vegetation, clouds across the sky.

 

24 comments

  1. Lynne Ayers

    I find apertures and F-stops so confusing, though you have explained and illustrated it well – perhaps I’m meant to stick with my point ‘n’ shoot.

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  2. petspeopleandlife

    I am astonished each time that you post a scene from Wales. You have yet to post a so-so photograph. Beauty is literally at your fingertips. And this is a really nice post for anyone that does not understand depth of field. You are a teacher as well as a gifted photographer.

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  3. Pingback: Weekly Photo Challenge: Focus | Pilot Fish
    • Mike Hardisty

      One those grab shots Chas and being in the right place at the right time. I was actually photographing some weird rock formations behind me. Turned round, saw this scene with the sun and thought its got to be a photograph…

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      • Chas Spain

        I love that when you’re focussed on something (even mowing the lawn) and then look up to see the light doing something clever and unexpected. Being outside is always a good start.

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  4. sustainabilitea

    Mike, excellent explanations and I love your first two photos. I was blessed to visit Wales for a short while not many years ago and found it beautiful indeed.

    janet

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  5. Ishaiya

    Wow! This is breathtaking. It’s like a painting that I would most definitely hang on my wall. Beautiful! Thanks for sharing 🙂

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