Lots of people nd cameras to be mysterious contraptions
packed with circuits and sensors that somehow spit out
photos. When we charge the battery and press the shutter, we
know that we’re going to get a photograph, but the process by
which that photograph is created is a total mystery to most
people
To start at the beginning, the word camera comes from
“camera obscura” which is Latin for dark chamber. An early
mechanism for projecting images onto paper so that they
could be traced, the camera obscura eventually led to the
development of the camera as we know it today, a device
used to capture visual images with a medium that can record
light intensity — either lm negatives or digital sensors
With traditional lm cameras, light passes through a lens and
is recorded using a chemical process in which sensitive
photographic lm is exposed to this light during an exposure
while the shutter is open. This photographic lm is a sheet of
plastic coated with an emulsion containing light-sensitive
crystal halide salts held together with gelatin. To nally create
a visible image, chemical processes are applied to the lm
during the lm development process
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Digital cameras, which currently make up the vast majority of
the camera market, use an electronic sensor in place of lm,
typically a CCD image sensor or a CMOS image sensor. The
basic idea is that both CCD (charge-coupled device) and
CMOS (complementary metal-oxide semiconductor) image
sensors convert the light’s energy into voltage, which is then
converted into digital information
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DSLR – A digital single-lens re ex camera. Any digital
camera with interchangeable lenses where the image is
viewed using a mirror and prism and the image is taken
directly through the lens. What you see in your view nder is
what the lens sees
EV – Exposure value; this is a number that represents
the various different combinations of aperture and shutter
speed that can create the same exposure effect
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Bulb – the “B” setting on your camera where the shutter
remains open for as long as the button or cable release
(remote trigger) is pressed
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Bracketing – Taking a series of images at different
exposures. You may see a setting on your camera that says
AEB (auto exposure bracketing). Bracketing is often used
when creating HDR images or in dif cult lighting situations
where you may want to have a range of exposures from light
to dark
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Aperture – The variable opening in the lens through
which light passes to the lm or digital sensor. Aperture is
measured in f-stops. I like to compare it to your pupil, which
opens and closes to allow more or less light into your eye
depending on the brightness level of the room
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The processor in your camera takes the information
obtained by the digital sensor and converts it into an image
le that gets written to a memory card in the format that
you’ve selected — usually Jpeg or RAW
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ISO – Represents the sensitivity of your camera’s
digital sensor to light. The lower the number (ISO 100), the
less sensitive to light; the higher the number (ISO 3200), the
more sensitive to light. A higher ISO allows you to shoot in
low-light conditions
Shutter speed – The amount of time the shutter is open
during an exposure. The shutter speed controls the
appearance of motion. Use a fast shutter speed (such as
1/2000s) to freeze motion or a slow shutter speed (such as
1/30s or longer) to blur moving objects
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F-stop – A measure of the aperture opening in the lens
de ned by dividing the focal length of the lens by the
aperture diameter. The sequence of f-stops features
multiples of the square root of 2 (1.4): 1, 1.4, 2, 2.8, 4, 5.6, 8,
11, 16, 22, etc. Though these numbers are rather cryptic,
make sure to remember that each step is double the amount
of light. Know that, and you’ve won half the battle
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Exposure – The total amount of light reaching the digital
sensor. It is determined by the aperture, shutter speed, and
ISO
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Exposure compensation – Modifying the shutter speed
or aperture from the camera’s recommended exposure to
create a certain effect or correct for exposure problems. Your
camera reads light bouncing off your subject and is designed
to expose for medium gray. So when photographing a
subject that is lighter or darker than 18% gray, you can use
this setting to tell the camera the proper exposure (by dialing
in – or + exposure compensation)
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Zoom lens – Any lens that has a variable focal length,
such as a 24-70mm or an 18-55mm lens. You generally
zoom in or out by rotating the barrel of the lens
Prime or xed lens – Any lens that does not zoom and
features a set focal length, such as a nifty 50mm lens
Remote trigger or digital cable release – A device that
allows the camera to be red without pressing the shutter
button or touching the camera. Helps eliminate camera
movement during long exposures
Macro lens – A lens that focuses very close to a
subject, so you can capture highly detailed, magni ed
images
“Normal” lens – Generally a 50mm lens (on a full-frame
camera). This lens closely parallels what the human eye
sees. If you have a crop-sensor camera, a “normal” lens will
be closer to 35mm
Telephoto lens – Offers a tighter eld of view than a
normal lens (i.e., it takes more magni ed images). Generally
from around 70mm to 300mm. A super-telephoto lens is
usually 300mm or longer
Wide-angle lens – A lens that features a wider eld of
view than a normal lens. Generally spans from over 10mm to
under 50mm. Depending on the focal length, there may also
be edge distortion (i.e., in super wide-angle lenses)
Tilt-shift lens – A special-effect lens. Allows for
realignment of the plane of focus (tilt). Allows for adjusting
the placement of the subject within the frame without angling
the camera, thus keeping parallel lines from converging
(shift). A popular lens for architectural and landscape
photographers and is becoming more widely used by portrait
photographers to create a unique, stylized look
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Camera resolution – The dimensions your camera’s
sensor is capable of capturing, expressed in megapixels.
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Camera modes – There are four standard camera
modes.
Auto mode selects settings without user input. Manual mode
allows the user to control the ISO, shutter speed, and
aperture. Shutter Priority mode allows the user to select the
ISO and shutter speed while the camera selects the
aperture. Aperture Priority mode allows the user to select the
ISO and aperture while the camera picks the shutter speed.
Program mode allows the user to select the ISO while the
camera picks the aperture and shutter speed.
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Full-frame vs crop/APS-C sensor – A full-frame sensor
is roughly the size of 35mm lm. Most lenses create a circle
of light just large enough to cover the 35mm sensor area.
But in a crop-sensor camera, the physical size of the sensor
is smaller; it only captures a portion of the entire image the
lens is projecting, effectively cropping out part of the shot.
Common crop factors are 1.5x and 1.6x, so if you use a
50mm lens on an APS-C camera, it offers a 75mm focal
length equivalent
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This is not the only factor in image quality, but the greater the
resolution, the larger the prints you can produce without
signi cant loss of quality (generally speaking)
JPEG vs RAW – Two different image le types. Most
cameras have the ability to shoot in JPEG and RAW. If you
choose JPEG, the camera will shoot a RAW le, process it
using the picture style you’ve selected in your menu, save it
as a JPEG, and discard the RAW version. If you choose
RAW, the resulting le will be larger, carry more information,
and require software to process. It gives you – the
photographer – more control over the nal look of the image