Smarter Than a Camera?

This page is for people who want to be smarter than a camera.  When you set your camera to AUTO mode you loose control.  This page will tell you how to take control and why you should.  With these basic concepts mastered you can start taking better pictures and prove you are smarter than the camera.

Pictures are about light.  The camera helps you manipulate the light.  There are three basic ways to control the amount of light that gets into your camera:  ISO sensitivity, shutter speed and aperture.

ISO Sensitivity

A higher ISO number makes the camera more sensitive to low light but it makes the picture more grainy or less sharp.  The best quality is normally at ISO 100.  You will need to experiment to see how high an ISO number you can use with your camera before the grain becomes unacceptable.  You may need to use a higher ISO setting to take pictures indoors without using a flash.
Click here for
more technical info about ISO sensitivity.

ISO 100 (enlargement)

ISO 1600
Notice how the high ISO grain makes the smooth gray rocks look spotted.

Shutter Speed

The shutter opens and closes to let light into the camera.  The longer the shutter is open the more light gets in. Shutter speed is measured in fractions of a second.  The larger the number the less time the shutter is open.  Example: 250 = 1/250 second.  A short shutter speed can help stop movement - which may or may not be a good thing. 
Click here for more technical info about shutter speed.

Waterfall at 1/1000 second shutter speed:
Notice the high speed shutter froze drops of falling water.

Waterfall at 1/30 second shutter speed:
The slower shutter speed blurs the moving water and looks more natural.

The AUTO mode on your camera would not know you were taking pictures of a waterfall to adjust the shutter speed appropriately.


The aperture is an adjustable size opening in the lens. It is represented as a ratio of the focal length of the lens to the diameter of the opening so the larger the number the smaller the opening and the less light gets in.  The aperture of 8 is shown as f/8 and is also called an f-stop.
Click here for more technical info about aperture.

Common Camera Exposure Settings

 Shutter     Aperture
 1/30  f/16
 1/60  f/11
 1/125  f/8
 1/250  f/5.6
 1/500  f/4
 1/1000  f/2.8
All the above combinations let in the same amount of light.

Lens Focal Length

The length of a camera lens is related to its magnification power.  For most cameras a lens of about 50 mm is normal.  A wide angle lens would be shorter than 50 mm and would make things look smaller but allow you to get a wider view without backing up.  A telephoto lens would be longer than 50 mm and would bring distant objects closer just like binoculars.
Click here for more technical info about focal length.

Depth of Field

Most modern cameras will automatically set the distance from the camera to the subject. This is called focusing.  There will always be a range of distances that will be in focus - this is called the depth of field.  The depth of field is affected by the aperture size and the focal length of the lens.  A wide angle lens has a larger depth of field than a telephoto lens. A larger aperture has less depth of field than a small aperture. 
Click here for more technical info about depth of field.

Flower at f/22 (small aperture) with a 70 mm lens:

Flower at f/2.8 (large aperture) with a 70 mm lens:
The blurry background effect is called bokeh.

The AUTO mode on your camera would not know to adjust the aperture to blur the background to make your flower stand out.

Camera Mode Settings

Many cameras have various mode settings that will allow you to override the automatic settings - but only if you are smarter than the camera.
M = manual mode - you have to set the aperture and the shutter speed.
P = program mode - camera sets aperture and shutter speed but you can make other adjustments like setting underexposure and overexposure.
A or Av = Aperture priority - you set the aperture and the camera automatically adjusts the shutter speed.  Use this when you want to control the depth of field.
S or Tv = shutter (time) priority - you set the shutter speed and the camera automatically sets the aperture. Use this when you need to freeze motion.

Camera Quick Reference

You Must Remember This...

Visit These Sites for More Information

Photography 101
Picture Correct
Wikipedia on photography