Thursday, February 6, 2014

Depth Of Field - Part 2



Yesterday’s blog discussed how to easily control Depth Of Field (DOF) by the use of f/stops. A larger lens aperture of f/2.8 or f/4 or f/5.6 will generally provide shallow DOF, allowing you to blur the background. Smaller apertures of f/8 or f/11 or f/16 or less will provide deep DOF rendering everything sharp.

But as is often the case, in photography as well as in life, there are no true absolutes. The distance that the lens is from the subject, and the distance between the subject and the background, also affects DOF.   This is illustrated in today photos.

Both images were shot at f/8, but the DOF of the dragonfly shot is shallow, while the DOF in the scenic is deep.  Why? In the dragonfly image the lens was relatively close to the dragonfly and the dragonfly was relatively far away from the foliage in the background, whereas in the scenic the lens was relatively far away from all the elements in the image.

This may seem confusing at first, but if you re-read the above paragraph it will begin to sink in.

So in matters of love, distance may make the heart grow fonder but in photography greater distance makes everything sharper.

The best way to cement the concept of DOF is to practice, practice, practice. DOF is a simple function of the optics of lenses, but you do not need to understand the mathematical or scientific parameters of how lenses work in order to control DOF successfully. If you understand the basics as explained in yesterday’s and today’s blogs, you will be well on your way to producing better images and having more control over how they look.

Dragonfly: Shutter Speed 1/500 sec. Aperture f/8.  ISO 200.  Lens: Canon 70-200mm f/4L IS set at 200mm.  Camera: Canon 40D.  Handheld.

Alaska scene: Shutter Speed 1/1600. Aperture f/8.  ISO 400.  Lens: Canon 17-40mm f/4L set at 40mm.  Camera: Canon 40D.  Handheld.

TODAY’S QUOTE: “Look and think before opening the shutter. The heart and mind are the true lens of the camera.”   --Yousuf Karsh

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