Having control
When it comes to having control over your exposures, you really need to understand aperture. A fundamental understanding of what aperture is and how it effects your photos is a basic foundation for taking your photography to the next level.
In a nutshell, aperture is defined as a hole or opening through which light travels. When you depress the shutter on your camera, light travels through the lens and is captured on the sensor (or film) of your camera. But what does aperture really mean?
The way aperture works on camera’s is somewhat counter-intuitive. A smaller aperture number (often referred to as the f-stop) means a bigger opening for light to travel through. A larger aperture (f-stop) means a smaller opening for light to travel through. The size of that opening greatly affects how an image will look.
A larger opening (smaller f-stop/aperture) will greatly decrease your depth of field. That means what you are focusing on will be in sharp focus, but other parts of the image might be blurry. In the above example, I used a relative small aperture (f/2.9). As you can see, the “control” key is in sharp focus, but the rest of the keys aren’t. The further away you get from the “control” key, the less in focus the image is.
Conversely, if I had taken that photo with a large aperture – say f/22 – all of the keys and the screen would be in critical focus. Of course there are trade-offs to aperture. Changing the aperture of your camera requires an equal, opposite change in shutter speed to maintain a properly exposed image. For example, if I had a properly exposed image at f/4.0 and a shutter speed of 1/60s and I decided to change the aperture to f/2.8. My image would require an equal, opposite change in shutter speed to remain properly exposed. Changing the shutter speed to 1/125s is the correct choice here.
Let’s take a moment to analyze that. If a smaller aperture really means a bigger opening for light to pass through. Then by creating a larger opening for light to pass through, we are allowing more light through to the sensor. If you have a properly exposed image, and allow more light, you get what’s called an over-exposure. One way to combat an over-exposure is to reduce the duration of time light is allowed to pass through the lens – a ha! A faster shutter speed will reduce the amount of light! By reducing your aperture one f-stop, you need to increase your shutter speed by one f-stop. Increase your f-stop, you would need to decrease your shutter speed by the same amount.
I’m sure many of you are thinking “whoa, this is waaaaay too complicated!”. Luckily, most manufactures have a special shooting mode called Aperture Priority. Aperture Priority allows you to choose what aperture you want, and the camera will automatically choose the correct shutter speed to make a properly exposed image. Check your camera’s user guide to find out if you have an Aperture Priority shooting mode on your camera – and figure out how to turn it on! When I’m out shooting, I can honestly say I’m in Aperture Priority about 90% of the time.
Aperture is a complex subject that can’t be covered in just a few paragraphs. I’ll be touching on this subject in more detail in the weeks to come. However, I was playing around with my old point-and-shoot tonight and snapped this picture and decided to share. While it certainly helps, this picture is also proof that you don’t need a $3000 camera to take a nice photo. My Nikon Coolpix P50 is over two years old and cost about $130 from B&H Photo :)
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