Hi folks! Welcome back
to my second entry on the Visual Technology Production, which entirely focused
on digital image photography and manipulation. I just remembered we have two
international students from Nigeria and I need to use English as my medium of
interaction from now on to enable them to understand my blog afterwards. And by
the way, a very warm welcome to you both and welcome to Malaysia, a place like
no other! Chee gitew~
So I will recap on what
I had covered on for the first blog previously. I did an introduction to
different types of cameras and their brands and functions respectively. I also discussed
on the types of DSLR cameras, Digital cameras, and even DSLM cameras, the
latest and upgraded types of DSLR cameras. Eventually, there are differences and
similarities for each of the cameras that I had been mentioned earlier. Many of
you thought that different brand has different types of cameras have different
functions and the more expensive it was, more functions were included. That was
wrong! There were many similarities actually which will be further discussed in
this entry later.
Firstly, there are lots
of camera brands being promoted and bought by professional photographers and we
mostly saw them using Nikon or Canon for a professional photography. I’ve
attached a link that shown a comparison
between DSLR and SLR type of cameras,
DSLR
and SLR. Which one is better?
Digital
cameras and DSLR. Which one is better?
Okay guys, are you still with me? So far we had
covered the differences and comparison of DSLR and SLR cameras and I’ve shown
you the examples of DSLR and digital cameras that mostly used by professional
photographers to shoot professional photographs. You noticed that the pictures
that they took were beautiful thanks to the techniques that they used in taking
pictures. Focal length of lens and aperture, shutter speed and exposure as well
as ISO and functions are crucial in obtaining
beautiful pictures depend on the environment and emotion settings itself. In
the next post, I will go in details on it and hang on tight folks!
We started with:
Aperture
A large aperture (1) and a small aperture (2)
The aperture is a hole or an opening through which light
travels. The aperture of an optical system is the opening that determines the
cone angle of a bundle of rays that come to focus in the image plane. The aperture
determines how collimated the admitted rays are, which is of great importance
for the appearance at the image plane. If an aperture is narrow, then highly
collimated rays are admitted, resulting in a sharp focus only for the rays with
a certain focal length. This means that a wide aperture results in an image
that is sharp around what the lens is focusing on. The aperture also determines
how many of the incoming rays are actually admitted and thus how much light
reaches the images plane (the narrower the aperture, the darker the image for a
given exposure time). In the human eye, the pupil is the aperture.
Shutter speed
How shutter speed works
Shutter speed on the
other hand is the aperture diaphragm of a lens (bigger or smaller values) and
timing (open and close) of the camera’s shutter curtain- both perform the tasks
of regulating the amount of light entering the camera and expose onto the film.
The shutter speed scales engraved on the shutter speed dial of conventional
camera bodies with a shutter speed ring OR via some flickering digital numerals
on the LCD screen like: 1/8000, 1/4000,
1/1000, 1/1500, 1/250, 1/125, 1/60, 1/30,
1/15, 1/8, 1/4, 1/2, 1 or -1, -2 etc. are essentially indicators of the
duration (timing) at which the shutter curtain opens up and closes during an
exposure process. A 1/125 setting means the shutter curtain open and close
within one hundred and twenty five of a second while 1 means a one full-second
the shutter opens up during exposure to absorb the available light source onto
the film to form an exposure.
Mechanism of shutter speed in SLR cameras
The shutter speed dial provide
the selection of shutter speeds, and indicates the timing of the shutter open
and closes. A fast shutter speed such as 1/500 sec will close faster than, say
1/2 sec exposure time. In this case, the shutter curtain will close very fast
and thus resulting in less light entering the film. Illustration used here is a
older horizontal shutter design, more info is available by < clicking here >.
Exposure
A long exposure of stars rotating around the southern and northern celestial poles.
A photograph of sea after the sunset with an exposure time of 15 seconds.
Exposure
in photography is the amount of light per unit area (the image
plane luminescence times the exposure time) reaching a
photographic film, as determined by shutter speed, less aperture and scene
luminance. In digital photography, “film” is substituted with “sensor”.
Exposure is measured in lux seconds, and can be computed from exposure value
(EV) and scene luminance in a specified region.
In
photography jargon, an exposure generally refers to a single shutter cycle. For
example: a long exposure refers to a single protracted shutter cycle to capture
enough low-intensity light, whereas a multiple exposure involves a series of
relatively brief shutter cycles, effectively layering a series of photographs
image. For he same film speed, the accumulated photometric exposure (Hv)
should be similar in both cases. More reading references on exposure can be
found <here>
ISO settings
In
traditional (film) photography ISO (or ASA) was the indication of
how sensitive a film was to light. It was measured in numbers (you’ve probably
seen them on films – 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.
In
Digital Photography ISO
measures the sensitivity of the image sensor. The same principles apply as in
film photography – the lower the number the less sensitive your camera is to
light and the finer the grain. 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 higher the ISO you choose the noisier shots you
will get.
The
one on the left is taken at 100 ISO and the one of the right at 3200 ISO
You
can see larger sized images of both shots here for
the 100 ISO and here for
the 3200 ISO). 100
ISO is generally accepted as ‘normal’ and will give you lovely crisp shots
(little noise/grain).
The Exposure Triangle
It is at the intersection of these three elements
that an image’s exposure is worked out.
Most importantly – a change in one of the elements
will impact the others. This means that you can never really isolate just one
of the elements alone but always need to have the others in the back of your
mind. The Exposure Triangle consist of:
- ISO – the measure of a digital camera sensor’s sensitivity to light
- Aperture – the size of the opening in the lens when a picture is taken
- Shutter Speed – the amount of time that the shutter is open
Mastering the art of exposure is something that
takes a lot of practice. In many ways it’s a juggling act and even the most
experienced photographers experiment and tweak their settings as they go. Keep
in mind that changing each element not only impacts the exposure of the image
but each one also has an impact upon other aspects of it (ie changing aperture
changes depth of field, changing ISO changes the graininess of a shot and
changing shutter speed impacts how motion is captured).
The great thing about digital cameras is that they
are the ideal testing bed for learning about exposure. You can take as many
shots as you like at no cost and they not only allow you to shoot in Auto mode
and Manual mode – but also generally have semi-automatic modes like aperture
priority and shutter priority modes which allow you to make decisions about one
or two elements of the triangle and let the camera handle the other elements.
So that's enough for today's lesson. In the next
entry, I will discussed in details on visual photography especially in
techniques and applications in daily life as well as visual modification/manipulation
by using cameras and media storage devices respectively. Hope you gain some
knowledge especially the differences in between aperture, shutter speed,
exposure and ISO settings in your own camera afterwards. Fighting!
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