Improve Your Photography - Part 10, Aperture and Shutter Speed

For any control over the camera, one has to know how aperture and shutter speed combine to
create an exposure.
An aperture is defined as: The device that controls the amount of light entering a camera.
It controls the amount of light entering the camera through a circular diaphragm designed
blade.
The aperture opens in a circular manner. The wider the aperture, the more light it allows
through. And vice versa for when it is closed down.

Shutter speed: A shutter blade that allows light to enter the camera for a determined time.

Exposure:
Exposure is the resultant image that a camera produces once the shutter release is pressed. It
is the resultant image that comes from a combination of the shutter speed of the shutter and
how much light the aperture let through the diaphragm.
Aperture and shutter speed are the two controls a camera uses to make an exposure on the
film when you "take a picture". Shutter speed is the speed with which the camera's shutter opens when the picture is taken. It is the "click" you here when you push the button.

You probably have seen a dark picture or light pictures; these are illustrations of incorrect
exposures. With Compact cameras, these properties are most of the time beyond your control,
as the camera is working in “auto” mode. The more control you have over an image, the less
incorrect exposures you will have. We are lucky that cameras produce good results 95% of
the time- allowing us to enjoy our photography without worrying too much.
However, creative control comes with you controlling the camera, so your camera will have
to move off the “auto mode” and start working in Aperture” and “Shutter” Priority modes on
your camera.
These modes give you control over what aperture to use and how you can control the
resultant image, allowing extensive creative control.

Added to this equation is Depth of Field (DOP).

Aperture also controls Depth of field. The smaller the hole in the diaphragm; the greater the
DOP. The larger the hole in the Diaphragm; the narrower the DOP. We will cover this later,
for now lets look at shutter speed.

Things to consider when choosing a shutter speed:
There are some basic rules that we need to know:

• Most individuals cannot hold a camera steady (without blur in the photo) for anything
slower than 1/60 of a second.
• Subjects need to be extremely still/steady in order to not show motion/blur in the
image less than 1/60 sec
• Fast moving subjects tend to need shutter speeds of 1/250 of a second or faster into
order to freeze motion or prevent blur.
• The faster the subject, the faster the shutter speed needed
• Low levels of light limit one to a slow shutter speed
• High levels of light may limit one to fast shutter speed
• Thus for low light- one needs support to get a steady shot (or flash)
• For High light levels, can hand hold and good for action shots
ISO
Iso is the digital cameras sensitivity to light. As with film, and asa, iso is determined by an
increase in numbers. As each number doubles, so does the sensitivity of the sensor.
Ie: iso goes up as 100, 200, 400, 800, 1600 etc
With each increase, the sensitivity of the sensor increases.
If all other factors were to remain constant and iso had to increase, then the shutter speed
would have to also increase. For each increase in iso, the shutter speed would halve. This is
due to the sensor being twice as sensitive to light (it needs half the amount of light to make an
image) and thus the shutter speed halves.
One problem with iso is that as it increases, so does images quality decrease. Thus it is almost
not worth taking photographs at iso’s above 800, unless you are going for a specific effect.

Conclusion
Shutter speed, aperture and iso go hand in hand in determining how your creativity. You need
to know how they affect one another and how you can use them to your advantage.

For more information on Photography courses and how to improve your photography see here.

All text copyright C4 Images and Safaris