Shoot Better Photos: Basics of DSLR Controls

When a photographer starts talking about shooting photos, words and acronyms like Shutter Speed, Aperture, ISO, MegaPixel, White Balance, or AF Area can be talked about.  The problem is that a lot of people have no idea what these terms mean.  Books have been filled explaining these ideas, so I'll try and keep this entry as filled with information as possible, without overwhelming everybody with too much all at once. This article will go over the basics of what these terms mean and how they can be used, and I will follow up on these controls work on your DSLR in another article. 

On a side note, if you have a point and shoot camera (anything pocket sized), these controls are generally not available on cameras that size.  

Let's start at the beginning - shutter speed, aperture, and ISO.  These three settings control how much light gets into the camera and how that light is received by the camera's sensor.  In order to take a balanced picture, the amount of light that reaches the camera's sensor has to be just right.

When a picture is taken, the lens opens up for a specific amount of time at a specific width. This allows just the right amount of light to get into the camera's sensor.  This light reaching the sensor is what produces an image.

If too much light gets in, you get an "overexposed" picture with lots of white and washed out details.  

However the opposite is also true.  If too little light gets in, the image is "underexposed" with black areas and not much definition.

Luckily, your camera is smart enough to balance these settings to get your picture correctly exposed almost every time.  As you can see here, the camera slightly overexposed this picture on automatic mode.  The wall above the speaker is washed out with no definition - this is what can be avoided using manual settings.

Shutter Speed

Shutter speed is a measure of how long the lens stays open.  A faster shutter speed, 1/100 of a second or higher, will allow you to "freeze frame" whatever is in front of you, but lets less light into the camera.  In an indoor setting, this will usually cause the image to be underexposed without the aid of flash.  A longer shutter speed will allow more light into the camera, but can cause motion blur.  A tripod can be infinitely helpful to stabilize the camera and prevent blurring.  A good rule of thumb for handheld shots is about 1/30 of a second to keep from blurring.

Aperture

Aperture is sort of like the pupil of your eye in that it opens wider as light decreases to let in more available light.  If you have a quick shutter speed, a wider opening in the aperture will allow more light to enter the lens.  The diameter of an aperture is measured in f-stops. A lower f-stop number widens the aperture and allows more light onto the camera sensor.  Higher f-stop numbers make the camera's aperture smaller so less light hits the sensor.  Aperture can also have an effect on the depth of field in the image.  Higher f-stops (smaller diameter, less light getting to the sensor) allow more of an image to be in focus, and if you have enough light, this is usually a good idea to make sure your subject is in the best focus.  Lower f-stops allow for a very cool isolation of your subject by blurring out the details of anything in front or behind it.

These two concepts are very interrelated in that the faster the shutter speed, the larger the opening of the lens and vice versa.

ISO

So now that we can control the amount of light that gets into the camera which is very helpful if we have an ideal amount of light wherever we're shooting.  However, we live in the real world and shoot pictures in many places where the lighting is far from perfect.  For these situations, we can use ISO to control the camera sensor's sensitivity to light.  ISO 100 is the norm for outdoor shooting and will offer superb color and image rendering.  Higher ISO's will allow brighter pictures with less light, but this comes at the expense of image quality.

If you're new to all this, hopefully I haven't caused your brain to explode quite yet!  Just keep in mind that the best way to learn about your camera and how setting work is to just go out and shoot photos.  Start to play with some of the settings and see if you can make any cool effects, and if all else fails, your camera has a manual that will help explain these settings in more detail.

Good luck, and happy shooting!