Basics of Photography – Beginners Guide
Most
of us either own or have used a D-SLR or use cameras which empower us with the
ability to manually make changes to the camera settings, so it’s definitely
useful to understand those setting and in time master them, while the “Auto”
mode or built in presets could get you good results, learning and understanding
how to use the manual functions effectively would yield you even better results
and the satisfaction of being able to capture an image just the way you want
it.
Let’s
try and understand the three main functions Aperture, ISO and Shutter Speed.
1) What is Aperture?
Aperture
is the opening in the lens through which light passes and enters the body of
the camera. The larger the
opening the more light gets in and inversely the smaller the opening the less
light gets in.
Aperture
is measured in F-Stops and determines the size of the aperture, for example
f/1.4, f/2.0, f/2.8,f/4.0,f/5.6 etc.
It’s
important to keep in mind that the small number f/1.4 is larger than f/2.8 and
much larger than f/5.6.
The
smaller the f-number the larger the opening the more light enters the camera
body.
Your
probably wondering this is good information but what about implementation,
so let’s discuss that.
The
size of the aperture has a direct impact on the depth of field, which is the
area of the image that appears sharp. A small f-number such as f/1.4 (bigger
aperture) will isolate the foreground from the background by making the
foreground objects sharp and the background blurry, while a large f-number such
as f/8.0, (smaller aperture) will bring all foreground and background objects
in focus.
Every
lens has a limit on how large or small the aperture can get. This information is usually printed on the
lens itself, for example on my Sony Nex-5 its 3.5-5.6/18-55, where 3.5 is the
largest aperture and 5.6 is the smallest. 18-55 is the focal length of the lens
(we could discuss the relation between aperture and focal length in another
topic)
The largest aperture of the lens is much more important than the smallest, because it shows the speed of the lens. Larger maximum aperture means that the lens can pass through more light, and hence, can capture images faster in low-light situations.
The largest aperture of the lens is much more important than the smallest, because it shows the speed of the lens. Larger maximum aperture means that the lens can pass through more light, and hence, can capture images faster in low-light situations.
Examples of
apertures that is suitable for the respective kind of photography.
Landscape
photographers usually use small aperture settings (large f-number) this ensures
that from the foreground to the horizon the subject is relatively in focus.
Portrait
photographers usually use large aperture settings (Small f-number) this insures
that the subject is in focus while the rest is blurry, this emphases the subject
while blurring and background distractions.
Summary:
High
Aperture - f/2.8 or lower – Shallow depth of field – Ideal for Portraits
Low
Aperture – f/8.0 or Higher - Extended depth of field – Ideal for Landscape
Photography
Side note – The lens
is sharpest at the centre of the aperture range, for example aperture range of f/1.4,
f/2.0, f/2.8,f/4.0,f/5.6, the lens would yield the sharpest image at f/2.8
(other effecting factors - ISO, shutter speed).
2) What is ISO?
ISO
is the sensitivity of the image sensor to light.
The
lower the number (e.g. 100,200) the less sensitive the camera is to light but
it produces less noise (barely visible) which means high quality pictures.
The
higher the number (e.g. 12,800,25,600) the more sensitive the camera is to
light but it produces more noise and relatively low quality pictures with lot
of noise (grains in the photograph)
So when
would you use a low or a high ISO?
Since
the lower ISO gives the best image
quality we would love to use it all the time, but since the sensitivity of the sensor is
relatively low with lower ISO it would make sense to use it in situations where
there is ample light available (a bright sunny day, outdoors).
However
in low light situations (indoors, evenings etc) because there is hardly any
light to work with, the ISO would need to be increased so that the sensor can
become more sensitive to the available low light and be able to capture the
subject, bumping up the ISO enables us to capture images in relatively low
light situations but at the expense of introducing noise and reducing the
overall quality of photographs.
Typical ISO
sequence
100
200 400 800 1,600 3,200 6,400 12,800
The
important thing to understand is that with each stop (e.g. from 100 to 200) the
sensitivity of the sensor to light is doubled. So at ISO 12,800 the senor is 8
times as sensitive which means the time required to capture the image is
reduced by 8 times. (Higher Shutter Speeds)
Summary:
As
far as possible try to use the lowest ISO to yield the best image quality, try
tweaking the Aperture and shutter speed accordingly, increase the ISO has a
last resort.
Side note – Usually
ISO up to the third last stop should yield decent workable photographs
e.g. In the above “Typical ISO sequence” ISO up to 3,200 would yield a decent
photograph with some noise. (This might be different depending on the camera
you use and is subjective to personal preference of image quality)
3) What is Shutter
Speed?
Shutter
Speed is the length of time the camera shutter is left open to allow light to
expose the camera sensor.
Shutter
speed is measured in seconds or fraction of seconds where 1/250 is faster than
1/15 while 1” is much slower then both. Seconds
are usually denoted by the symbol “.
Higher
Shutter speeds are ideal for capturing still images of “motion” for example
1/500 would be fast enough to capture still images of most humans in action.
While a Slow shutter speed of 1” would create
a blurring effect, it would make flowing water look like milk.
Some cameras
also have a “bulb” mode where the shutter is left open for has long as you keep
the shutter button pressed this mode makes for some interesting light painting
photographs.
While
choosing the shutter speed it’s important to know that anything slower that
1/60 would introduce blur in your photographs due to hand shake. The immediate
solution would be to use a Tripod of use a lens or camera with image
stabilization.
The
safe shutter speed for hand-holding the camera would be to choose a shutter
speed with a denominator that is larger than the focal length of the lens.
For
example if you use a lens with a focal length of 55 mm a shutter speed of 1/60,
1/125 or higher would be ideal.
Summary:
Higher
shutter speeds 1/250 and above are ideal for capturing still pictures of motion
(humans, birds, objects etc)
Shutter
speeds between 1/125 and 1/60 would best for capturing regular human movement
and would not require a tripod.
Slower
shutter speeds of 1/15 and below would introduce motion blur and would require
a tripod.
Side note – When the
shutter speed is changed, you would also need to pay attention to the Aperture
and ISO. Let’s say the shutter speed is changed from 1/60 to 1/125 this would
result in half has much light entering the camera, so to compensate you would
either need to increase the ISO (e.g. from 100 to 200) or increase the Aperture
(e.g. f/4.0 to f/8.0)
Summary - Aperture,
ISO and Shutter Speed
Changing
Aperture changes depth of field.
Changing
ISO changes the image noise
Changing
Shutter Speed changes how motion is captured
Taking
a Great picture is a balancing act between these three elements of photography.
The
best way to learn and get better at photography would be to master the basics
and then combine that knowledge with your Artistic side. Just keep on exploring the world around you
and your camera and take great pictures J
In aperture section-
ReplyDelete" A small f-number such as f/1.4 (bigger aperture) will isolate the foreground from the background by making the foreground objects sharp and the background blurry"
Actually- low aperture wont isolate the foreground. It would isolate your subject from the rest of the frame. Even If your subject is in the foreground, a small aperture number would blur everything in the foreground as well as the background except the subject.
Second important factor in DOF is focal length. wide angle lens on f/1.4 would have lesser or almost no bokeh (blur) effect. Focus point will remain sharpest but background and foreground blurs are less prominent, also larger area remains sharp. But f/1.4 with a higher focal length (55mm, 70mm etc( would have purely the subject in focus and rest of the frame would appear totally blurred.
Lastly- aperture is an important factor while buying a new lens. The lower the aperture number, the better the ability of the lens to shoot in low light conditions. Also called a faster lens or faster aperture. Such lenses would reduce your dependence on the ISO which might cause your pics to appear grainy at high ISO numbers.
It is possible to compare two lenses on the same.
Lens A has focal length from 18mm to 140mm min aperture is f/1.8 - f/5.6
This means the lowest aperture number possible at 18mm is 1.4 and at 105mm is 5.6
Lens B has focal length from 17mm to 130mm min aperture is f/1.8 - f/5.6
How much light enters each lens at their lowest and highest focal lengths can be estimated by applying a calculation as follows:
f= focal length
Light that enters the lens at min aperture on Lens A at 18mm (f/1.8) = 18/1.8 = 10
Light that enters the lens at min aperture on Lens B at 17mm = 17/1.8 = 9.44
So at the lowest focal length Lens A allows more light so is considered a lens with faster aperture or better in low light.
Light that enters the lens at min aperture on Lens A at 140mm = 140/5.6 = 25
Light that enters the lens at min aperture on Lens A at 130mm = 130/5.6 = 23.21
Lens A is faster at the highest focal length as well.
Assuming both lenses are made of similar components, Lens A would be considered a faster lens.