Wednesday, February 5, 2014

Depth Of Field - Part 1



Depth of Field. Not a phrase that trips off the tongue easily. It is also a concept that many photographers are either not familiar with, or do not fully understand. This is the start of a series of articles explaining Depth of Field and how to use it to your best advantage.

So, what IS Depth of Field (DOF)? Basically it is how to control which elements in your picture are sharp, and which ones are not. Depending on your subject, you may want most elements in the frame to be sharp, as in the scenic in today’s blog, or you may want to blur the background so it does not detract from the main subject as in the butterfly shot.

You achieve whichever effect you want by controlling the f/stop you use. The operative words in that sentence are YOU and CONTROLLING. I feel compelled to point that out before going on because it is important to note that there is now software that can blur certain areas of an image, or sharpen them. Although I hate to be be too judgmental about these kinds of software, I really do not like them. “Why,” you might ask, “does she dislike them so much?” You might be thinking “she uses Lightroom to optimize images, so why is software than can sharpen or blur any different?”

In my opinion it is very different because it encourages a lack of knowledge, a lack of forethought, and a lack of control. Yes, there is that “control” concept again. I have confessed many times to being a control freak in some ways, and I admit it again now.

The way for YOU to CONTROL Depth of Field is really quite simple, and does not require fancy software, complicated calculations, or a Ph.D in physics. All you need to know is that large apertures  -  f/stops of 2.8 or 4 or 5.6  -  create shallow DOF as shown in the butterfly image, and smaller apertures  -  f/stops of 11 or 16 or smaller create deep DOF as shown in the scenic. That’s it. If you know how to change your f/stops, you can control DOF.

So that is the basic concept. The finer points will be discussed in another blog this week.   

Butterfly  -  Shutter Speed 1/125.  Aperture f/5.6.  ISO 100.  Lens: Canon 70-200mm f/4L IS with 1.4x extender for an effective focal length of 280mm.  Camera: 40D. Handheld.
Scenic  -  Shutter Speed 1/250 sec.  Aperture f/13.  ISO 200.  Lens: Canon 10-22mm f/3.5-4.5, set at 13mm.  Camera: Canon 40D.  Handheld.

TODAY’S QUOTE: “You can’t depend on your eyes when your imagination is out of focus.”  --Mark Twain

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