The following glossary is not a precise technical
definition of terms, but instead is an attempt
at explaining photography terms in simple layman's
Focal Length Multiplier)
A camera mode that attempts to use a fast
enough shutter speed (by upping the ISO)
to prevent camera shake.
Using a higher ISO usually results in higher
noise in your images.
Do not confuse with "optical image stabilization" or "image sensor shift" technology
where either the lens or CCD image sensor
is stabilized to prevent camera shake. This is known as mechanical or true image stabilization. (see Image Stabilization)
A new take on this feature is the "electronic"
blur reduction that can be performed in-camera
after the picture has been taken. This uses
software to basically "sharpen" the image
so it appears sharper. Again, do not confuse
with true image stabilization.
see Image Stabilization
||Also refered to
as f/stop, f/value, aperture value. The size
the lens opens to allow in light. A large
aperture is denoted by a small number, e.g.
F1.8, while a small aperture is denoted by
a large number, e.g. F16. A "fast"
lens is one with a large maximum aperture.
||Select an aperture
(f/stop) and the camera chooses the best shutter
speed. Use this mode to control the depth
of field, e.g. select a small f/stop for landscape
photography to ensure maximum depth of field,
and a large f/stop for portrait photography
to throw everything, except the subject, out
(pronounced BOH-KEH), and increasingly referred
to in print as "Bokeh"
||Japanese word meaning
"fuzzy" and referring to the out-of-focus
(OOF) portions of a picture. A lens is said
to have "good boke" if the OOF is
pleasant and does not detract from the main
subject. A lens with good boke produces out
of focus smooth-edged highlights and reproduces
an out of focus point of light as bright in
the middle and progressively getting fainter
with a fuzzy edge.
|Bulb (shutter speed)
||When set to the
Bulb setting, the shutter remains open as
long as the shutter release button is depressed.
This allows for real night photography, and
is ideal for taking multiple bursts of fireworks
on one frame.
||Cropping a picture
simply means to cut out a portion of the picture.
For example, you may have extraneous details
in your picture you do not want to display
or print, so you "crop" it out.
Notice, no enlargement is performed when you
crop a picture. Often, you will read the term
"100% crop" and all it means is
that the photographer does not want to post
the complete picture (could be 3MB+ in size)
and so crops out the relevant part and post
that as a "100% crop." No enlargement
or reduction performed.
Focal Length Multiplier
Not to be confused with "Crop"
of a picture, these terms are exclusively
used in the context of relating focal length
to field of view (FOV), using a full-frame
sensor size (24x36mm) as a reference.
When a 35mm lens is used on a digital SLR
using an image sensor that is smaller than
full-frame, the smaller sensor records only
a "crop" of what a full-frame
sensor can, thus recording a narrower field
For example, an APS-sized image sensor
is about half-frame and therefore has a
crop factor, or focal length multiplier,
of 2x (more accurately, 1.6x).
The term focal length multiplier is commonly
used because, to obtain an accurate indication
of the actual field of view covered, we
multiply the 35mm focal length of the lens
by the crop factor (focal length multiplier)
to obtain a 35mm focal length equivalent.
Technically, lenses made specifically for
a smaller than full-frame image sensor has
no crop factor. Thus, we don't specifically
speak of a crop factor for P&S cameras.
However, because image sensors in P&S
cameras come in many different sizes, the
specified focal lengths of the lenses do
not accurately represent the actual field
of view recorded and cannot be directly
compared one to another. They do not really
make any sense until we can relate all of
them to a standard reference. By using a
full-frame sensor and the lenses made for
them as our reference, we can then assign
a "35mm Equivalent" focal length
to each lens/sensor size combination to
obtain an accurate indication of the field
of view covered.
Using "35mm Equivalent" focal
lengths, a 35mm-50mm lens is considered
normal (35mm is a slight wide-angle, but
pretty much the norm in today's P&S
cameras), a 28mm or less is a wide-angle,
a 100mm-200mm is a medium telephoto, a 300mm-400mm
(and longer) is a long telephoto.
of Field (DOF)
||The distance wherein
objects are in focus. The smaller the aperture,
the greater the depth of field achieved. [more...]
|Depth of Field Preview Button
A button (usually found around the lens mount) on a DSLR that, when pushed in, closes the lens to the metered aperture ("stops down the lens") to allow you to check the DOF.
DSLRs with APS-sized sensors usually have viewfinders that are smaller than on DSLRs using a fill-frame sensor. The smaller viewfinder often makes it very difficult to judge DOF when the lens is stopped down.
And, since the aperture selected might sometimes be small and so return a dark view which might make it even more difficult to ascertain the DOF, some photographers prefer to take the shot and review the DOF on the big and clear LCD of their DSLR.
||The different modes
the camera provides for controlling exposure,
e.g. Auto, Manual, Shutter Priority, Aperture
Priority. See also: Shooting Modes.
Focal Length Multiplier
The image sensor is the equivalent of 'film'.
An image sensor contains millions of pixels
(megapixels) arranged in a matrix whose
job is to catch and record light when you
take a picture. Each pixel registers the
brightness -- or, intensity -- of the light
falling on it. By using colored filters
and an array of small lenses, the image
sensor is able to record color values in
a small footprint.
A high resolution
image sensor can capture
much more variation in light than a low
resolution image sensor,
and can therefore reproduce an image more
faithfully and realistically.
The size of an image sensor also contributes
to the quality of the images captured. In
general, the larger the image sensor, the
in the images.
Cramming ever more megapixels onto a small image sensor tends to reduce the image quality, especially introducing more noise. The sweet spot seems to be 7MP on a 1/1.8-in. image sensor.
A technology that stabilizes either the
lens ("optical image stabilization") or image sensor ("image sensor shift" or "CCD-shift") to effectively reduce
blur due to camera shake when using a slow
This allows the hand-holding of a camera
at slower shutter speed (without upping
Do not confuse with "Anti-Blur," "Digital Image Stabilization," "Picture Stabilization," or "electronic Vibration Reduction" where
the camera either selects a higher ISO to allow
the use of a fast enough shutter speed to
counter the effect of camera shake or uses in-camera processing to "sharpen" the image.
Optical Image Stabilization and Image Sensor (or CCD) Shift Image Stabilization are also known as mechanical or true image stabilization.
In photography, an ISO number is an indication of the sensitivity of the image sensor, where a higher number indicates higher sensitivity.
This is usually expressed as a range, e.g. ISO 100 - 1600.
A higher sensitivity allows us to take pictures in low light without using flash. However, this gain usually comes at a price: as we amplify the light signal, we also amplify the noise signal, and high ISO images are usally more "noisy" than low ISO images.
Noise reduction software can smooth out the noise but it comes at the expense of losing fine detail.
Larger image sensors have larger pixels with better light signal to noise ratio, and produce "cleaner" high ISO images.
Derived from the Greek isos, meaning "equal".
International Organization for Standardization chose this short all-purpose name instead of using its acronym "IOS" so that whatever the country and language, the short form of the organization's name is always "ISO" (pronounced "eye-so").
However, if you find others pronouncing it as "eye-s-oh" (as I do), leave us alone -- please don't make it into a fight ;o).
How the camera measures the amount of light
available to expose a picture.
Centre-Weighted: Readings are taken at
various part of the picture, with a special
emphasis for the centre.
Spot: Readings are taken at a specific
Besides the above two light metering options,
each camera manufacturer has its own variations,
such as Matrix Metering, Multi-Pattern Metering,
objects, by usually moving close up. A steady
tripod and a macro ring light ensure well
Millions of pixels (usually used in reference
to the resolution of an image sensor).
A digital camera can have an image sensor
that is rated 4.2 megapixels but delivers
an effective resolution of 4.0 megapixels.
The higher the effective resolution, the
higher the quality of the picture that can
be recorded (providing the lens is able
to produce the quality image in the first
Some digital cameras might advertise the
"interpolated" pixels. As an example,
Fujifilm's Super CCD image sensor can capture
"effective" pixels of 3.1 megapixels,
then its software kicks in and interpolates
them up to 6 megapixels. Do bear in mind
a digital camera that outputs 6 interpolated
megapixels will never deliver the same quality
that a real 6 effective megapixels digital
camera will, and should still be compared
to a 3 effective megapixels digital camera.
What is important when comparing resolution
of different image sensors in digital cameras
is the effective megapixels.
Original Equipment Manufacturer.
While this is not technically a digital
photography term, you may have come across
it when reading about how many of the major
digital camera companies do not actually
make the cameras bearing their brands, and
wondered if one brand was any different
The question is sometimes yes and sometimes
The OEMs outsource the manufacture to low-cost third party manufacturers and then
rebrand the cameras, sometimes adding value
in the form of better lenses and firmware,
and sometimes not.
Now you know why some of these digital
cameras have very similar feature set and why
many even look similar, minus some cosmetic
|Oily Nose Syndrome
Where oil from your nose smears the LCD.
Some digital cameras have viewfinders that are so flushed with the body that when you bring the camera up to your eye, you end up smearing nose oil all over the LCD.
When you use a Neutral Density (ND) filter on your lens, it allows you to optically cut out the amount of light going through the lens, but otherwise does not [ideally] affect image quality.
Of course, the quality of the glass used matters. It is also sometimes possible to stack one ND filter on top of another to vary the amount of light you want to reduce.
Usually used on bright sunny days to cut down on the amount of light and thus allowing the photographer to use a slow shutter speed for recording effects depicting motion (e.g. "water as a cloud").
When a slow shutter speed is used (1/30
sec. and lower), the image degrades due
to the buildup of electronic signal ("noise").
Software in the digital camera automatically
compensates to reduce that noise. Most digital
cameras has noise reduction that automatically
kicks in at slow shutter speeds.
Similarly, when a high ISO is used, noise
starts to show in images. For now, most
consumer digital cameras are not good at
high ISOs, even though the camera might
Noise exhibits itself as luminance and
chrominance noise. Luminance noise is the
digital equivalent of film grain, and appears
as brightness variations. Chrominance noise
(or colour noise) appears as coloured splotches.
see What Is... Noise?
||An image editing
software. The most popular.
Photography + Digital Pixels
Digital Photography is a marriage of traditional
photography (you still gotta develop an
eye for what makes a good picture) and digital
Digital Photography = Photography
+ Digital Pixels = Photoxels.
A technique to
allow you to focus on a subject that is not
at the center of the screen. By default a
camera will focus at the center of the screen.
By pressing the shutter release button half-way
you can lock focus on your off-center subject,
then recompose and depress the shutter release
fully to take the shot.
Pre-focusing also helps to eliminate shutter lag that is mostly due to the time the camera takes to lock focus.
For our purpose, let's just define this
as the number of pixels used to capture
an image. In reality, excellent image
resolution is achieved by a combination
of pixel count (image sensor resolution)
and lens resolution.
If the image sensor resolution is expressed
as numbers such as 2048x1536, just multiply
them out and divide by 1 million to get
the resolution in megapixels. In this case,
we get 3+ megapixels.
Usually the higher the image sensor resolution,
the better the image quality.
The amount of control you have in choosing
how your digital camera captures an image.
All digital cameras usually have an Auto
mode: the camera decides for you the best
shutter speed/aperture settings.
Shutter Priority: Allows you to decide
the shutter speed (e.g. fast at 1/500 sec.
for stop action photography, or slow at
2 sec. for night photography), and the camera
decides the best aperture.
Aperture Priority: Allows you to choose
the aperture (e.g. large at F1.8 for portrait,
of small at F16 for landscapes).
Manual: You have complete creative control
in selecting both the shutter and aperture.
Scene Modes: Pre-set exposure control (shutter/aperture
combination, plus other adjustments, such
as white balance, exposure compensation,
etc.) for various common picture situations,
such as Night Scene, Portrait, Landscape,
The time elapsed between pressing the shutter
release button and the camera actually taking
A short shutter lag (around 1/2 sec. or
less) is desirable since it allows you to
take candid shots.
A long shutter lag (around 1 sec. or more)
means that you will find it difficult to
capture the picture at the exact moment
you desire (since the camera takes it one
second or more after you depressed the shutter).
Using the pre-focusing technique can help eliminate shutter lag that is due to the relatively long time that some digital cameras takes to lock focus.
||Select the shutter
speed and the camera chooses the best aperture.
Use this mode to freeze fast moving action
or emphasize motion. For example, select a
fast shutter speed (e.g. 1/1,000 sec.) to
freeze a cyclist zooming by. Or, select a
slow shutter speed (e.g. 1/30 sec.) to capture
the cyclist as a blur to emphasize the speed
of the motion.
||The length of time
the shutter blades stay open to allow light
into the camera. The longer the shutter
stays open (e.g. 1/30 sec.), the more light;
the shorter the shutter stays open (e.g. 1/1,000
sec.), the less light. Snapshots and action
photography usually requires a fast shutter
speed to freeze action; landscapes usually
requires a small aperture for maximum depth
of field, and hence a longer shutter speed
for properly exposed pictures.
||The digital medium
that replaces film. A number of competing
storage media cards are offered, with the
most common ones being CompactFlash (CF) and
SecureDigital (SD). [Sony uses its own proprietary
Memory Stick, Olympus has its proprietary
see Image Stabilization
(Do not confuse with electronic Vibration Reduction that uses in-camera processing to sharpen the image)
balance refers to the ability to adjust
colors based on white as a reference color
to give as true a white as possible; in
the process, all the other colors are also
Auto WB (AWB): the camera determines and selects the correct color temperature for white.
Some preset white balance settings
are daylight, cloudy, tungsten, or fluorescent.
Using white balance properly is essential
in digital photography.
Optical vs. Digital vs. Total
Whereas an optical zoom uses the optics
(lens) of the digital camera to move you
closer to your subject, a digital zoom simply
uses the existing image and enlarges it
Enlarging the image digitally reduces picture
quality, and should therefore usually be
avoided. However, a judicious use of digital
zoom may sometimes yield images that are
of quite acceptable quality. So, use with
Some manufacturers label their lenses with
the "total zoom" by multiplying
the optical with the digital. Ignore total
zoom claims because you can use any multiplier
digital zoom you want in an image editing
What is important when comparing
digital cameras is the optical zoom.
Digital zoom can always be achieved later
in an image editing software, such as Photoshop,
so should not really be a determining factor
when choosing a digital camera.
see Optical vs. Digital Zoom