Shutter Speed
The amount of time the shutter is open, that your camera is
exposed to the scene you’re attempting to capture/the amount of light let in.
Shutter speed is measured
in seconds
or in most cases fractions of seconds. The bigger the
denominator the faster the speed (ie 1/1000 is much faster than 1/30).
In most cases you’ll
probably be using shutter speeds of 1/60th of a second or faster
This is because anything slower than this is very difficult
to use without getting camera shake. Camera shake is when your camera is moving
while the shutter is open and results in blur in your photos.
If you’re using a
slow shutter speed (anything slower than 1/60) you will need to either use a
tripod
or some some type of image stabilization, or at least set
it on a stable surface.
Shutter speeds
available to you on your camera will usually double (approximately) with each
setting.
As a result you’ll usually have the options for the
following shutter speeds –
(FAST) 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8 (SLOW)
This ‘doubling’ is handy to keep in mind as aperture
settings also double the amount of light that is let in – as a result
increasing shutter speed by one stop and decreasing aperture by one stop should
give you similar exposure levels (but we’ll talk more about this in a future
post)
Some cameras also
give you the option for very slow shutter speeds
that are not fractions of seconds but are measured in
seconds (for example 1 second, 10 seconds, 30 seconds (very long.) These are
used in very low light situations, when you’re going after special effects
and/or when you’re trying to capture a lot of movement in a shot.
Some cameras also give you the option to shoot in ‘B’ (or
‘Bulb’) mode. Bulb mode lets you keep the shutter open for as long as you hold
it down.
When considering
what shutter speed to use in an image you should always ask yourself whether
anything in your scene is moving
and how you’d like to capture that movement.
If there is movement in your scene you have the choice of
either freezing the movement (so it looks still) or letting the moving object
intentionally blur (giving it a sense of movement).
To freeze movement in an image, you’ll
want to choose a faster shutter speed (fast_shutter)
To let the movement blur you’ll want to choose a slower shutter speed (slow_shutter_water)
The actual speeds you should choose will vary depending
upon the speed of the subject in your shot and how much you want it to be
blurred.
Motion is not always bad.
Water flowing (slow_shutter_water)
Lights moving (slow_shutter_lights)
Stars moving (long_exposure_stars)
Choose a longer shutter speed. However use a tripod or
you’ll run the risk of ruining the shots by adding camera movement (a different
type of blur than motion blur).
ISO
Sensitivity of “film” to light, in digital, it is measuring
the sensitivity of the image sensor measured in numbers:
100, 200, 400, 800 etc.
The lower the number, the lower the sensitivity of the film
and the finer the grain in the shots you’re taking. The higher the number,
the rougher the grain.
The same principles apply in digital as in film photography – the lower the number the less sensitive your camera is to light and the finer the grain/noise. Higher ISO settings are generally used in darker situations to get faster shutter speeds (for example an indoor sports event when you want to freeze the action in lower light) – however the cost is noisier shots.
When choosing the ISO setting I generally ask myself the following four questions:
Light – Is the subject well
lit?
Grain – Do I want a grainy
shot or one without noise?
Tripod – Am I using a
tripod?
Moving Subject – Is my
subject moving or stationary?
If there is plenty of light, I want little grain, I’m using a tripod and my subject is stationary I will generally use a pretty low ISO rating.
If it’s dark, I purposely
want grain, I don’t have a tripod and/or my subject is moving I might consider
increasing the ISO as it will enable me to shoot with a faster shutter speed
and still expose the shot well.
Situations where you might need to push ISO to higher settings include:
Indoor Sports Events – where your subject is moving fast yet you may have limited light available.
Concerts – also low in
light and often ‘no-flash’ zones
Art Galleries, Churches
etc- many galleries have rules against using a flash and of course being
indoors are not well lit.
Birthday Parties – blowing
out the candles in a dark room can give you a nice moody shot which would be
ruined by a bright flash. Increasing the ISO can help capture the scene.
Basically, situations where
you can’t get better light, but need to capture the scene.
Aperture/Depth of Field
Aperture is the hole inside your camera lens
When you adjust the aperture, the hole gets bigger or
smaller, which in turn controls how much light can pass through your lens.
Aperture settings are expressed by F-stops and are
represented by numbers (i.e. f/2, f/5.6/f/11-reference week 2 white board)
Crayon Picture: Shutter speed and ISO remain untouched and
only aperture is changed, so you can see how ithe light is affected by changing
the aperture. The larger the aperture, the more light and is overexposed vs a
smaller aperture with less light and is underexposed.
Ruler Picture: Aperture can affect the depth of field—the
distance where objects in your scene are in focus. The larger the aperture
opening, the shallower the depth of focus. This is because only the light that
hits the area in focus will be rendered sharply on the digital sensor or film,
and other areas will be blurry. But, the smaller aperture will allow for a
deeper focus for what is in focus, because there is no extra unfocused light
spread out.
“Seeing”
Being able to observe the world and imagery around you
better will help you know what to do when you are creating, retouching, or
editing an image. Often, you will be working on an image and you know there is
something not quite right about it, but can’t figure it out. Observing the
world around you will help
Light
Using high contrasted areas can draw the eye's attention. Sometimes high contrasts created from light and shadow is called chiaroscuro and can add drama to an image.
Some good examples of imagery using light and shadow are here.
Line
The quality and direction of line in an image can create illusions of distance and space, and move the eye around a composition. You can use leading lines, like train tracks to lead the eye into the distance.
Some good examples of imagery using line here.
Color
Color can drastically change the mood of an image.
We often have personal or cultural associations with color.Take a look at some monochromatic (images focusing on the use of one color) pictures and notice the what kind of associations you might have with that color and how it alters your perspective on an image.
You can create points of interest to an image where to opposite colors meet like red and green or blue, and orange.
Some good examples of imagery using color here.
Assignment
Please set up a still life at home using at least three objects with direct light. Be creative with your still life. Think about texture, light, line, color, and composition.
Take 3 photographs of your still life using a different depth of field for each, from the same position, using a tripod or a still surface. Make sure your camera is set to take RAW pictures.
- Foreground subject in focus with blurry background
- Background in focus with blurry foreground
- All composition elements in focus
Required Reading
http://www.fuelyourphotography.com/how-to-compose-shapes-lines-light-dark-colors-textures/
http://digital-photography-school.com/rule-of-thirds
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