the three building blocks of exposure

I've had the amazing chance at taking two different photography classes over the past few weeks. They have been so helpful, and one of my Twitter followers asked me if I'd pass along some information to you.

Of course I can!

So, today I am going to tell you about the Three Building Blocks of Exposure.

They are:

1. ISO

2. Shutter Speed

3. Aperature (my personal favorite!)

Now, hang with me. These can get kind of confusing, but, in the end, you'll figure it out, I'm sure!!!

First, let's talk about ISO. ISO stand for International Organization for Standardization, but don't worry-- that's not on the quiz. ISO basically refers to your camera's sensitivity of sensor to light. If you are going to be blowing your photo up to a large size, you will want a low ISO. You will also want a low ISO if you are shooting brightly-lit scenes or when you are able to use a tri-pod in low light situations. Use a high ISO for dimly-lit scenes or for capturing fast action (this ties in to shutter speed, which we will talk about next).

Also, a note about high ISOs-- they tend to produce and generate more "noise" in your photographs. "Noise" is basically that grainy-looking-ness on your images. Compare the following two photographs:

The photo on the left has an ISO of 100. The photo on the right (the grainy image) has an ISO of 3200.

OK, now, let's talk about Shutter Speed. Shutter speed refers to the duration of time your sensor is exposed to the light through the lens. This number is measured in fractions of a second on your camera. For example, a very fast shutter speed would be 1/650. A very slow shutter speed would be 1/6. You would use a fast shutter speed to capture movement with no blur (like to photograph a child running). A fast shutter speed "freezes" your subject in motion. A very slow shutter speed would be used to show the motion, such as moving water or, again, a child running. A slow shutter speed will show blur.

Longer shutter speeds are for dimly-lit situations when using a tri-pod. Anything less than a shutter speed of 1/60 needs a tri-pod, or your photo will come out blurry from where you were moving the camera.

Most of the time, you will use a fast shutter speed.

This is a fast shutter speed-- probably around 1/500.

This is a slow shutter speed-- probably around 1/30.

Finally, let's look at aperature, my favorite of the three building blocks. Aperature is what separates a snapshot from a photograph, in my opinion. Aperature refers to a variable diaphram within the lens, which, as it opens and closes, allows more or less light through to the sensor. Aperature is represented by an f-number, or more commonly, an f-stop.

This is where it gets a little tricky-- the higher the numeric value, such as f22, the smaller the opening; the smaller the numeric value, such as f8, the larger the opening. The smaller the opening, the greater the depth of field. The larger the opening, the less the depth of field.

Now, what in the world is depth of field? I'm so glad you asked-- depth of field is what is in focus, or sharp, in your photo. Look at this example of a picture I made in Italy:

Notice how in the picture, the statue is really in focus, but the building in the background is not. That is aperature.

Aperature, when used correctly, can really enhance your photos! It can really help your photographs to stand out.
I hope this helps out some. I'm still working (and I'm sure I will continue to work) on mastering these three skills. Photography is an art, and it takes time and effort to learn your camera and learn all the different aspects of photography. I am, by no means, any expert-- I just wanted to help you learn a little more about how to move beyond making snapshots and move toward making photographs.

Only the picture of the statue is mine. The other two came from here and here.