A – D
Some cameras incorporate a light or infra red
beam to assist the autofocus system, other cameras use the
'pop-up' flash for assistance.
Aperture ( f number)
The aperture on a camera lens allows more or
less light to fall on the sensor, commonly known as ' f '
numbers, the larger the ' f ' number the smaller the 'aperture'
(lens opening). A smaller lens opening (large 'f' number)
has the effect of giving the image more depth in terms of
sharpness, which is important in macro photography.
When a camera is set on 'aperture priority'
it enables the user to set the aperture to the best setting
for the image being taken, in the case of intra oral images
this would be the largest number i.e. smallest lens opening
or aperture. 'Aperture Priority' would be the setting of choice
for Digital Compact Cameras.
In this mode the camera sets everything for
you, all you need to do is press the shutter. This is not
a good setting for intra oral in particular.
Auto White Balance
Different types of light have different colour
temperatures, the eye tends to compensate for this so we are
seeing 'natural' colours in most lighting conditions. When
you set your camera to Auto White Balance the camera automatically
adjusts the white balance to match the true colour of the
Many cameras have the facility to 'bracket'
either exposure and/or white balance, this means the camera
will produce 3 images at slightly differing exposure or white
balance settings, for you to choose the best.
Custom settings allow you to set frequently
used settings to memory and use those settings whenever necessary.
Cameras usually have at least 1 custom setting, some have
2 or 3.
Digital zoom extends the 'Optical zoom' range
of the camera by zooming in electronically on the image. These
images can be pixelated (individual pixels can be detected
in the image). Because the camera is enlarging the centre
of the image, just like enlarging a 35mm picture the user
will get a ‘grainy’ result. Images can be cropped
on the computer to achieve the same effect.
Glossary E – I
Sometimes referred to as a speedlight, this
is usually your main source of light for dental photography.
Some cameras allow you to vary the light output of the flash.
On all Digital SLRs and many compact cameras
the area where the camera focuses can be set, cameras will
default to the centre setting, but for intra oral, mirror
shots in particular it is useful to be able to dictate where
the camera focuses.
Most digital cameras have many more functions
than any 35mm equivalent ever had. Functions are the cameras
capability to perform tasks and generally make photography
easier for the user i.e. Auto White Balance
This is the fitting often found on top of many
cameras, it's primary use is for attaching additional flashguns
or power packs for accessories such as ringflash.
35mm film was graded in 'sensitivity', as in
Kodak Gold 200 and Kodak Gold 400. The 200(ISO) was a better
quality (definition) film than the 400 but less sensitive
to light, so if you were off on holiday to sunny destinations
the 200(ISO) would be good, whereas if you were wanting to
take interior shots without using flash 400 would be better.
Glossary J - M
Joint Photographic Experts Group, the most
popular and widely use image file format. It is called a 'lossy'
compression file but does the compression of files very well.
Settings of choice on many cameras would be the highest jpeg
setting available, often designated as superfine or fine.
Once the image is loaded onto your PC each time it is opened
and SAVED, the image is recompressed which will degrade the
image, ALWAYS MAKE A COPY TO WORK WITH!
This mode will naturally assume you are taking
a landscape, often focus is set on 'infinity' and aperture
is quite often a small number i.e. larger lens opening. Focus
and aperture are set this way because the subject is a distant
shot , and also little depth of focus is required.
Officially macro refers to life size or 1:1
images, macro in real terms refers to close up photography,
majority of digital compact cameras have a macro setting.
For taking intra oral images it is essential that a camera
is able to take 'close up' images. The common icon to depict
the macro setting is the 'tulip'. Some cameras will have a
macro mode as well as a 'tulip' setting, this is not a good
idea to use as it often disables the flash and endeavours
to get as close as possible to the subject to achieve maximum
magnification. This is explained more on the techniques pages.
Cameras with manual control give you the ability
to override camera auto or programme settings, for most applications
in Dentistry this is essential to get good consistent results.
This refers to the number of pixels a camera
uses to produce it's images, the more pixels the better resolution
an image should have.
As with mobile phones the quality of these
movies are improving, though if you want to make a movie buy
a video camera, if you want high quality stills..buy a still
camera. Some cameras now have the ability to record in HD…well
worth looking at.
Glossary N - R
Night Scene Mode
With this setting the camera uses the flash
but also uses a slow shutter speed, this has the effect of
lighting the main subject, say a friend and then the slower
shutter speed also records the surrounding area thus giving
a more balanced exposure i.e. not too dark or too light. As
a slow shutter speed is used you will need to ask your subject
to keep still and also may need some support for the camera
to stop shake.
Unlike 'digital zoom' this moves the lens elements
to zoom in on the subject with little loss of detail.
With this setting the camera will choose a
large aperture i.e. small number, to render the background
out of focus, thus often giving a pleasing effect.
This mode sets everything for you but does
allow some degree of 'tweakin' by the user, unlike 'Auto Mode'which
doesn't give any user adjustable options.
Picture quality setting on cameras usually
refer to the jpeg cmpression settings, such as Superfine,
Fine, Normal (Canon PowerShot G6). This setting should not
be confused with 'Resolution'.
RAW doesn't actually stand for anything other
than it is the raw image data that is recorded and saved.
Unlike jpeg any processing is applied post photography, whereas
jpegs are processed at the time of photography
Resolution is measured in Megapixels, this
setting on your camera should be set to it's highest! Why
pay for 10 Megapixels and then set your camera to use only
5 or less?
Glossary S - V
This is rated as an ISO setting, details of
which can be found in this glossary under ISO
If taking photographs without the use of flash,
the shuutter speed setting is critical if you are to avoid
camera shake. Shutter priority can be used when photographing
x-rays.An x-ray is flat and requires little depth of focus,
but because you are not using flash the camera needs to either
be on a tripod or set to a shutter speed that will not invoke
'camera shake', hand held photography is difficult for most
at speeds below 1/60th second.
This mode aids the taking of Panoramic images
by shooting overlapping frames.
TIFF(Tagged Image File Format)
This is a file format option that was available
on many of the earlier cameras, it tends not to appear on
the newer models. Unlike JPeg, a TIFF file is uncompressed
and therfore by definition produces a higher quality image.
The file fomat still has it's uses though, if you have edited
a jpeg in Photoshop, an option to retain the quality and not
recompress the image on saving, would be to save as a TIFF.
TIFF files are generally very large.
Glossary W - Z
Setting white balance on your camera alters
the colours of your image. Most of the time 'Auto White Balance'
works well. If you are howevre getting inconsistent results
in terms of colour rendition when using flash for intra oral
images, a change to 'speedlight' balance often helps.