So you've got yourself an SLR camera but you can't quite get the hang of shooting in manual. The foundation of understanding your camera is going to be utilizing and knowing what we call the exposure triangle. Today we are going to talk about Aperture.
APERTURE
Also known as the "f/stop", this is the only part of The Exposure Triangle whose
limitations are determined by your lens. Controlling your aperture controls how
wide the blades within your lens will open. What can be misleading is that the
lower the number, the larger the aperture. For example a very small aperture is
f/22 and a very large one is f/1.2.
SHUTTER SPEED
The shutter speed is probably the easiest comoponent of The Exposure Triangle
to understand. It determines how quickly your camera's shutter will open and
close. A slower shutter speed will allow for more light to be let in your camera,
while a faster shutter speed will do the opposite.
ISO
By changing your ISO, you change how sensitive your camera's sensor is to light.
A higher ISO will create a lighter image, and vice versa. It should be noted that a
higher ISO will produce more grain in your image and soften the focus.
Aperture
How do I take photos in a dimly lit room? How do I get that blurry
background? What do I do when I'm taking a picture of a large group of
people?
The answer to all of these questions is to adjust your aperture.
I admit this may be the most difficult component of your camera to
understand but once you do, you will be able to do amazing things!
YOUR LENS
If you take a look at your lens, you will see some numbers with decimals listed. If
the lens is a zoom, then you may see two numbers. So what do these numbers
mean?
This number, or set of numbers, represent your lens's maximum aperture. For
example, if you have a 35mm 1.8, then your maximum aperture with this lens is
1.8. That is the most your lens can open to let in light. But what if your lens has
two sets of numbers? A common lens (also known as a kit lens, because it often
comes with your camera body) is the 18-55 f/3.5-5.6. HUH?! What does this
mean? That means that your maximum aperture will depend on the focal length
you're shooting. In this case, if you are at 18mm then you can dial your aperture
all the way up to 3.5 but if you zoom to 55m, the biggest you'll be able to get is
f/5.6. A prime lens (one that does not zoom) will have a fixed max. aperture. You
may find some zoom lenses with a fixed aperture, but these tend to be very
expensive.
DEPTH OF FIELD
Maybe you've heard this term before but you don't really understand what it
means. Your depth of field (DOF), simply put, is the perceived distance between
two points in your photo. One of these points will be in focus and one will be
blurry.The larger your aperture (the lower the f/stop), the more shallow your DOF.
For example, you may take a close up shot of your baby's face with your aperture
set to 1.8. When reviewing your photo, you may notice that your baby's nose is in
focus but his eyes are blurry. However, if you take a few steps back and take the
photo with the same aperture, you'll see that your baby's face is now all in focus
and the background behind him is blurry.
Another example would be if you are photographing a large group of people. A tip
I've heard is that your aperture should match the number of people in the picture.
I'm not sure that I completely agree but it's good advice to some extent. If I'm
shooting a couple my aperture is going to be much bigger than if I'm shooting a
group of 35. That said my aperture for a couple isn't necessarily going to be f/2
and it will almost certainly not be f/35 for the large group. Distancing yourself
from your subject(s) is a good way to keep them in focus without needing to
decrease your aperture to much. Distancing your subject from the background is
a great way to create DOF without adjusting your aperture.
A WORD ABOUT LIGHT
It should be emphasized that the aperture play an extremely important role in
creating a correct exposure in the camera. Remember, a lower number means a
larger aperture which means more light coming into your camera. A higher
number means a smaller aperture, and a darker image.
THE ADVANTAGE OF A SMALLER APERTURE
So now you know that shooting with a larger aperture gives you beautiful DOF,
with a creamy, blurred background (bokeh) and lots of light. So why would you
ever want to decrease your aperture? Well, there re actually quite a few
situations where a smaller aperture would work best. For starters, you may find
your images are not as sharp as they could be when shooting "wide open".
Turning your aperture up a few stops will help you create a sharper image. The
more you shoot with multiple lenses, the more you'll find that each lens has a
different "sweet spot" where it's sharpest. Of course, there are times when you
need an even smaller aperture. Shooting landscapes, or home interiors are two
times when a smaller aperture (higher f/stop) is preferred.
