Exposure – The absolute basics of photography.

Exposure – The Absolute Basics of Photography.

I often talk about specific areas of photography in this blog, but sometimes, I forget to cover the basics.  This post it is time to get back to the basics and make sure you remember the elements essential to good photography.  The most important thing to understand in photography is exposure.  It is essential that we capture the right amount of light to create a good photograph.  This is true in both film and digital photography; the rules apply equally to both.

Several components come together to create a proper exposure.  Although our cameras today can do terrific things with exposure in automatic mode, we’re here to help you understand how to do that on your own.  By learning to control your camera manually you’ll be able to be far more creative with your photography than running in auto mode will ever allow. 

For digital photographers it’s more important for you to get a good understanding of exposure than it is for a film photographer.  In digital you do have the ability to edit your photos before they’re printed, but it’s critical that you have good data in the image you capture.  That’s where it becomes essential to understand exposure and apply that knowledge to record a good quality image in the first place.

One rule above all others can help you learn to adjust exposure readily while you’re out shooting, the Sunny 16 Rule.  The Sunny 16 Rule: with your subject in full sunlight, use an aperture of f/16, at a shutter speed of 1/ISO.  By using this rule as a starting place for setting your camera, you can be very flexible in making well-exposed images, while maintaining your control over creativity.  This takes practice, so don’t get discouraged if you don’t learn it right away.

The elements that we must consider for creating a proper exposure are: 

  • Amount of light on our subject. –  Sometimes we can control how much light is on our subject, and others, we’re going to deal with whatever light is available.
  • F/stop (Aperture) – How much light we allow to come through the lens is controlled by our f/stop.  The f/stop is simply a method of controlling the size of the aperture (opening) the light is passing through as it comes through the lens.
  • Shutter Speed – How long we allow the light to come through the lens.  We want to control the length of time we expose a shot to capture the right amount of movement, or to stop the action.
  • ISO Speed – The speed at which our camera is recording the image.  ISO is directly tied to the quality of our images and we want to keep it as low as possible (i.e. 100) to maintain the best possible quality.  If we have very little light available and need a fast shutter speed, we may need to increase the ISO.  Just keep in mind that this will have a negative affect on the quality of the image.

I talked previously about using the correct f/stop for your subject (to control depth-of-field) and the correct shutter speed (to deal with motion), so this column is intended to help you bring it all together. 

If you want to make a portrait, you want to have very little depth-of-field, so you’ll want to use a wide open aperture, like maybe f/4.0.  So if you set your camera to Aperture Priority mode and set the f/stop to f/4.0, you can use the camera to take a meter reading on your subject.  Get near enough to your subject to NOT cause a shadow, point the camera and push the shutter release half-way down.  This will display the shutter speed in the viewfinder for you, so make a note of that display (yes, you need to read your manual to understand everything in that display).  Then switch your camera to manual mode, set the f/stop to f/4.0 and the shutter speed to whatever the meter reading provided on the display.  If your meter reading showed a shutter speed of 1/100th of a second, then set the shutter speed to 1/100th of a second.  Step back to where you want to shoot from and start shooting.  This will make your shots far more consistent than using an auto, or semi-auto mode.  Do the same thing with Shutter Priority mode if you want to use a particular shutter speed.  Once you’ve practiced this technique for a while you’ll learn to make adjustments on the fly fairly quickly, and you will be more comfortable over time.

The illustration I’ve included here might help you understand what you’re seeing inside your viewfinder.  Although this is a typical Canon display, it should be easy to translate to whatever appears in your particular display.

© 2009 Jeff Cowell, jeffcowell.com

~ by jrcowell on November 21, 2009.

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