All that you need to know about Digital Cameras
Buying a camera
There are many factors to consider when choosing a digital camera and
ultimately there is a compromise between performance and cost.
Points to consider:
- Higher resolution cameras produce better quality images than lower
resolution cameras but are more expensive to buy.
Images of 640 x 480 are good
enough for general purposes and can be downloaded quickly. Although it
is now possible to have images professionally printed on photographic paper,
the quality of the printed image is limited by the quality of the printer and
paper you use.
- Camera power supply can be a huge hidden cost. It is important to check
whether the camera uses rechargeable batteries, and can be connected to mains
power supply. It is worthwhile remembering that switching the camera on and
off uses power, so keep the camera on if you are taking a number of pictures.
- Cameras will have an optical viewfinder and/or a LCD monitor. The optical
viewfinder is like the viewfinder in a traditional camera. The LCD monitor
allows you to view, change, delete and save images stored in the camera. It
uses a lot of power, so remember to switch it off when possible, if you need
to save battery power.
- Accessing images can be a tricky one. It is possible to download images
from the camera onto the computer via a serial cable or USB port. This can be
time consuming! USB is 30 times faster than the serial cable. In some cases
the USB uses power from the computer, which will save your battery life as
downloading can use a lot of power. Floppy discs can be inserted in some
cameras and this is a really useful way of accessing
images if the camera is shared by groups. Each group can
insert their own floppy when they use the camera, eject it when they've
finished and pass the camera on!! The images can be instantly accessed on any
computer, no need to have specialist software, the camera, wires etc. This
also means the camera can be used somewhere else while you access your
pictures. Other cameras contain a removable memory card which fit into a
memory card adaptor. The adaptor looks like a floppy disc, is inserted in the
a:\drive and is as easy to use as a normal floppy disc.
- Does the price include accessories? If accessories are not included in
your package, you don't necessarily have to buy the manufacturers'
accessories, e.g. for certain Sony cameras there are a number of accessories
made by competitors that are of equally good quality but don't carry the
premium that Sony products do.
Your digital camera should fit your lifestyle, interests,
photographic needs, be easy to use, and give great results. You will
have to decide on the physical size of the camera, number of
megapixels
(the resolution), zoom capability, type and amount of memory, and other
features. Of course, a lot will be determined by how much you are
prepared to spend but high quality point-and-shoot type digital cameras
are now available for reasonable prices.
But above all, you need to be comfortable with the feel of the camera
and make sure it is easy to use. This may only come after you spend some
time using the camera and experimenting with various modes. But before
you go shopping, do some research, familiarise yourself with some of the
terminology, and find a knowledgeable sales person who can show you the
features and comparisons of various models in your price range.
Some Pointers:
Here are some of the features to look for in a digital camera.
Size, weight: You need to understand the compromises between size
and weight, features, performance and price.
Resolution: Start your camera search looking at a minimum of 3 Megapixels. 4 or 5+ Megapixels is preferred if you can afford it.
A good
2 Megapixel camera is acceptable if low price is the determining factor.
Anything less than 2 megapixels is not worth considering.
Optical Zoom: Minimum 3 x optical. Digital zoom ratings
are meaningless.
ISO - Equivalent Speed:
Capable of up to 200 ISO. 400 ISO or higher is nice but not essential.
Aperture: Look for a minimum of F2.8 at zero zoom. The larger the
aperture (lower number) the better.
Memory Storage: The type of memory card used is not terribly
important. Choose at least 128 Mbyte capacity and if you can afford it
carry another 128 MByte spare card. 512MByte cards are now quite
cheap - use one if possible. Excellent for those little video
shots.
File Format: Camera will have JPEG modes (in various settings).
TIFF or RAW mode option is nice but not essential.
Battery: A standard format (like AA) rechargeable is
preferred over a proprietary format. Always carry a charger and backup
battery pack/cells in your kit bag. I prefer to have Lithium
batteries - usually smaller but can have a longer life - more
expensive. You still need to carry a spare.
Flash: The built-in flash should be as far from the lens as
possible to minimise red eye.
PC Interface: A USB interface is standard and does the job. A
card reader is a handy accessory. A docking/charging station is nice but
not if it comes not at a large premium.
LCD Monitor: As large as possible but should not be a determining
factor in selecting the camera.
Modes: Review other modes the camera is capable of: such as flash
settings, manual overrides, macro (close-up) and movie mode.
A complete camera kit will consist of:
Digital camera with 128 Mbytes of memory ( 64 Mbytes is OK for a 2
Megapixel camera)
Spare 64/128 Mbyte memory card
Spare battery pack or rechargeable AA cells
Battery charger
USB cable
Camera bag
Optional
Slave flash
Memory card reader
Docking station ? if available and affordable
Table top tripod * Very useful for timed shots or video
shots!
Full tripod
Size and Weight
The camera should feel comfortable and secure in your hand. The controls
should be conveniently placed and easy to use; the menu display should
be easy to navigate. In essence, changing the camera?s settings should
be almost intuitive. You?ll need to decide if you want the camera to fit
in a shirtsleeve pocket, a pants pocket or no pocket at all. Aside from
the cost premium you will be paying for miniaturization, some of the
smaller cameras are amazingly capable and full featured.
Resolution
Resolution ? or the amount of ?fineness? or detail the camera can
capture - is measure in megapixels (millions of pixels). A pixel is a
?picture element? ? with each picture element capable of capturing (in a
camera) or displaying (on a display) the full colour spectrum. The more
megapixels, the higher the resolution and the more the photo can be
enlarged or cropped without seeing any loss in picture quality.
Nowadays, a 3 megapixel camera is considered to be the minimum
acceptable. This will yield good images up to 8 x 10 enlargement ?
provided the original image has not been cropped or heavily edited prior
to enlargement.
A 4 or 5 megapixel camera is preferred. These camera have
sufficient resolution for very good 8 x 10 and larger prints, plus allow
you to crop images quite severely yet still get good quality prints. If
you can afford a 5 megapixel camera or better ? go for it. But you will
only see a difference on extreme enlargements or highly cropped and
enlarged images.
Megapixels, Image Size and Quality Guideline
|
Megapixels |
Image Size in Pixels |
Quality Guideline |
| 2.1 |
1600 x 1200 |
High Quality 6" x 4" photos, very good 8 x 10? with no cropping. |
| 3.3 |
2048 x 1536 |
High Quality 8" x 10" photos |
| 4 |
2272 x 1704 |
High Quality 11" x 14 ? photos |
| 5.1 |
2560 x 1920 |
High Quality up to 16" x 20" and cropped, photo-quality 8" x
10?s from a fraction of the original image file |
File types and file size
JPEG is a file compression for photo images and what (normally) comes
out of your digital camera. Files saved in JPEG format will have a .jpg
file extension. Compared to an uncompressed file, an image saved in JPEG
result in a significantly smaller file size with minimal degradation in
quality. However, JPEG is a lossy compression format, meaning that each
time an image goes through JPEG compression, some quality or fine detail
is lost that cannot be recovered.
You should set your camera for best quality JPEG format, usually called
?fine? quality. If necessary you can always compress the file to a
smaller file size (for sending via email or posting on a web site) using
image viewing or editing software.
A true photo ?pro? may want to capture and output images in TIFF mode ?
an uncompressed format. The resulting file sizes are very large and your
memory card may only hold a handful of images. But for anything but the
most critical applications, you will not see any difference compared to
a high quality JPEG. TIFF and other non-compressed formats are best left
to professionals.
Zoom ? Optical and digital
Most cameras in the 2 megapixel and up category have zoom capability.
Digital cameras have two types of zoom, optical and digital. Don't be
influenced by the digital zoom rating of a camera. It is meaningless
(useless?) since digital zoom can always be done after the shot is taken
using your photo editing software. Optical zoom is all that matters
in the camera. A 2 x zoom is minimal and hardly worth the trouble. A
3 x zoom is a good choice though the price of 4 x zoom lenses is coming
down. With a 3 x zoom something 30 feet away can be made to appear as if
it was 10 feet away at maximum zoom.
Higher zooms are available, but once you get into a zoom of 6x and
higher, camera shake can be a problem, and you?ll need to consider using
a tripod or stabilizing method when shooting at these higher optical
zoom settings.
Aperture
If you care about taking pictures in low light look at the maximum
F-stop your camera can support. There is an iris in the lens and this is
a measurement of the maximum it can open up, it affects the brightness
of the image. F/2.8 is good and anything numerically less is better.
Maximum F-stop can also vary somewhat with zoom. High F-stop zoom lenses
have very large lenses at the front and would be heavier. F-stop also
affects depth of field, the range of distances for which the subject
will be in focus.
To get a general impression of light gathering performance look at the
size of the lens opening. Some cameras have tiny lenses - this means
that less light enters the lens and therefore the camera does not
perform so well in low light level.
LCD monitor
LCD?s (Liquid Crystal Displays) are power hungry and will use up battery
power very quickly if left on for extended periods. One tremendous
advantage of digital cameras is that you can immediately review the shot
you just took on the LCD and decide whether to keep it or re-do it. But
using the LCD as a viewfinder to frame a shot only works under ideal
lighting conditions. LCD?s ?wash out? outdoors in bright sunlight and
may be dim in low light conditions. LCD size should not be a big
determining factor in choosing your camera.
ISO Speed
Like conventional photo film, a digital camera uses the ISO rating to
denote its speed (sensitivity to light). The higher the ISO number, the
better the camera is of operating in low light, and the better it is
with indoor flash (flash will work further from subject since camera has
better low light sensitivity). But as the ISO number increases, picture
noise or graininess increases. Just like conventional film, there is a
compromise between film speed and graininess with digital ?film?. Your
digital camera will most probably have a nominal ISO equivalent setting
of 100. Most new cameras will allow you to manually set the camera to
other ISO settings (200, 400 and higher), but these should only be used
in situations with low light or when capturing high-speed action.
Otherwise, leave the ISO setting on ?Auto? and let the camera do the
work.
Battery
Battery life will depend on how much you use the LCD display, and how
often you use the flash. With a little care, a fully charged pack should
easily last a full day of shooting. It?s a good idea to start each day
of use with a fully charged battery. And remember that a charged battery
pack does discharge (slowly though it may be) even if you are not using
it. So get into the habit of keeping your spare pack or set of cells
under charge, ready to use at all times.
It?s nice to have standard rechargeable battery format such as AA so in
a pinch you can use off-the-shelf alkaline cells. But if a proprietary
battery is used, buy a spare, and charge/swap it alternately with the
original battery pack.
If you are using a docking station, the battery in the camera is
recharged when placed in the docking station. This is fine when working
at home. But when travelling, you probably won?t want to carry the
docking station and need to have a separate battery charger and spare
batteries.
Memory
There are many types of memory cards used. There is no one truly
superior to the other but some of the newer types, such as SD and xD,
are physically smaller and designed specifically for digital cameras
using new storage technologies. Memory types include:
Compact Flash
Micro-drive (in a Compact Flash II configuration)
Smart Media
Secure Digital (SD)/ Multi-Media
xD Picture Cards (eXtreme Digital)
Memory Stick (Sony proprietary)
You can never have enough memory! I recommend at least 128 Mbytes (for
anything with more than 2 megapixels) plus another 128 Mbytes as spare.
This will allow you to store about 160 shots for a 2 Megapixel camera or
about 60 to 70 shots for a 5 megapixel camera. These numbers can vary
greatly depending on the actual level of JPEG compression your camera
uses and the type or complexity of photos taken.
Flash
All point and shoot cameras have a built in flash, but this flash has
limited capabilities. If the flash is too close to the lens, it is prone
to create red eye. Even with red-eye reduction mode switched on, red eye
is hard to avoid when shooting with direct flash. Not to worry as your
image editing software can eliminate any remaining red-eye.
All cameras will have various flash modes such as auto, fixed-on, slow,
red eye reduction, and none.
A valuable accessory is a slave flash. This is a standalone flash
unit that is triggered by the built-in flash of the camera. You position
the slave flash to the side of the subject or bounce light from it off a
wall or the ceiling. The slave flash compliments the camera?s main flash
by eliminating harsh shadows and generally providing a better-lit scene.
Some digital cameras fire a ?pre-flash? prior to the main flash to allow
the camera to set white balance. In this case you will need a slave
flash that can be set to fire on the second flash pulse, but not all
slave flashes have this option. Also, you may have to set your camera to
?slow flash? for best operation with a slave flash. A little
experimentation may be required.
Some high-end cameras have a ?hot shoe? that allows you to attach a
higher power flash directly to the camera. This is better than the weak
built in flash but does not necessarily replace a well-placed slave
flash fired from at angle to the subject.
Modes
Macro
Most cameras have a macro mode that allows you to focus on objects
inches away from the lens. If you primarily take pictures of people and
landscape this does not matter. But if you want to take close-ups of
flowers small objects, this is an important feature.
Manual Modes
Some cameras allow you to manual adjust the camera for ISO speed,
weighted vs. spot exposure control (?scene modes?), and set aperture
priority or shutter priority or full manual mode. Most of the time,
you?ll probably leave the camera on ?auto? and use it as a ?point and
shoot? camera but it is nice to be able to have some manual control over
the settings. Whatever manual setting features are provided, it should
be easy to switch back to full ?auto? mode.
Movies
Some cameras have a movie mode that can capture a number of seconds of
low resolution movies. If this is of interest to you, compare the
capabilities of the cameras under consideration. This can be an
interesting feature to use.
Burst Mode
Most cameras allow you to take a series of quick, low to medium
resolution still shots to allow you to capture a sequence of
fast-happening events or take these at slightly different exposures
(called bracketing) to make sure you can a well exposed shot.
TV Out
In addition to the USB output used to transfer images to your PC, some
cameras have a TV Out that allows you to hook up the camera directly to
the video input of a TV. Again, this is a nice feature to have but
should not be a big determining factor is selecting your camera.
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