Sunday, December 6, 2009

First Week with a DSLR: Part 4

An Experiment
Your DSLR can do lots of great things so it's hard to know where to start when everything is new. Here is an assignment that can teach you a lot about your camera if you pay attention to what's happening.

The Setting:
For this experiment you still want to be outside in the daylight. And you'll want to go through this process multiple times with different subjects. Be sure to choose a moving subject a few times and be sure that there are lots of things in your image that are different distances from your camera. In other words, don't take a picture of a flat brick wall. Don't do any zooming or repositioning when you are going through one set of pictures.

The Settings:
You'll want your camera in Program Mode. This means the winding dial on the top should be on "P." Everything else should be normal - assuming you haven't fiddled with other settings.

What you need to know:
When you take a picture, your camera collects a proper amount of light to give you a good exposure. Your camera uses two variables to control how much light is collected. The key to this experiment is understanding that different combinations of these two variables can produce the same exposure.  It's the same as being able to multiply different combinations of numbers to get to 12.
  • 1 x 12 = 12
  • 2 x 6 = 12
  • 3 x4 = 12
You don't have to understand everything yet, just know that different settings can give you the same amount of light.

The Process:
Aim your camera at something and take a picture.  Now, while you are looking through the viewfinder, wind the command dial (pictured below) one click (either direction.)

In the viewfinder, you should see some numbers at the bottom change. In addition you should see "P" with an *.  (If all the numbers disappear, just push the shutter release down half-way.) What you have just done by winding the command dial is changed your two multiples without changing the product. So, for example, your camera may have chosen 2 and 6 to make 12 and turning the dial changed it to 3 and 4. So with these new settings take another picture. Wind and repeat until winding doesn't make a change to the numbers anymore.  Then go back to where you started and wind the other way.  You'll end up with a series of pictures with the same exposure using different settings. Do this all again aiming at different subject.  Then do it a few more times. If you ever feel like you've totally lost track of where you are, just turn your camera off.  When you turn it back on, it will start over.

Once you have done this four or five times (or more,) you can look at the result on your computer. Try to figure out what's happening. Check out some results here: Part 1, Part 2, Part 3.