With traditional cameras, the film is used both to record and store the
image. With digital cameras, separate devices perform these two functions.
The image is captured by the image sensor, then stored in the camera on a
storage device of some kind. In this section we look at many of the
storage devices currently being used.
Removable vs. fixed
storage
Older and less expensive cameras have built-in fixed storage that can’t
be removed or increased. This greatly reduces the number of photos you can
take before having to erase them to make room for new ones.
Almost all newer digital cameras use some form of removable storage
media, usually flash memory cards, but occasionally small hard disks, and
even the venerable floppy disk. Whatever its form, removable media let’s
you remove one storage device when it’s full and insert another. The
number of images you can take is limited only by the number of storage
devices you have and the capacity of each.
The number of images that you can store in a camera depends on a
variety of factors including:
The number you can store is important because once you reach the limit
you have no choice but to quit taking pictures or erase some existing ones
to make room for new ones. How much storage capacity you need depends
partly on what you use the camera for. If you’re used to shooting 5 or 6
rolls of standard film on vacation, your camera better be able to store
the same number of images or you’ll be out of luck.
Removable
storage
Since both flash memory cards and magnetic disks are widely used in
digital cameras, let’s pause here to look briefly at how these very
different forms of storage compare. Both types of storage devices share
some outstanding features:
Let’s take a look at the leading types of image storage devices in
digital cameras.
Flash memory cards
As the popularity of digital cameras and other handheld devices has
increased, so has the need for small, inexpensive memory devices. The type
that’s caught on is flash memory which uses solid state chips to store
your image files. Although flash memory chips are similar to the RAM chips
used inside your computer there is one important difference. They require
no batteries and don’t loose images when the power is turned off. Your
photographs are retained indefinitely without any power to the flash
memory components. These chips are packaged inside a case equipped with
electrical connectors and the sealed unit is called a card.
Flash memory cards consume little power, take up little space, and are
very rugged. They are also very convenient; you can carry lot’s of them
with you and change them as needed (assuming you can afford lots of
them).
Types of flash cards:
There is an old set up line for a joke that begins “I have good news
and bad news.” The good news is that we have these flash memory cards at
all. The bad news is that they come in a variety of formats that are not
interchangeable. Once you have a sizable investment in memory cards, you
are locked into using only those cameras that support your format.
Until recently, most flash cards have been in the standard PC Card
(PCMCIA) format that is widely used with notebook computers. However, with
the growth of the digital camera and other markets, a number of smaller
formats have been introduced. As a result of the competition, cameras
support a confusing variety of incompatible flash memory cards including
(but as the lawyers say “not limited to”) the following:
Each of these formats is supported by its own group of companies and
has its own following. If one will ever prevail over the others remains to
be seen.
PC Cards (ATA)
When laptop computers became popular, they didn’t have room for large
storage devices so small plug-in cards were developed. Initially called
PCMCIA cards (after the Personal Computer Memory Card International
Association), this name was later changed to PC Cards. However, not
everyone has switched to the new name so the cards are now called by two
names!
Whatever you call these devices, they are used in most notebook
computers and some cameras. About the size of a credit card, PC Cards come
in a variety of types or thicknesses, but it’s the Type I and II cards
that are used for solid state, or flash memory. Like CompactFlash and
SmartMedia, PC Cards are ATA compatible so they can be swapped between
devices and systems. (Any ATA-compatible card will work with any
ATA-compatible system, including digital cameras and almost all
computers.) These cards currently store up to 1.2 Gigabytes.
CompactFlash cards
CompactFlash was developed by SanDisk Corp and uses the popular ATA
architecture that emulates a hard disk drive. The cards are 1.433-inches
(36.4 mm) wide by 1.685-inches (42.8 mm) long-about the size of a
matchbook. At the time this was written, CompactFlash looked like the
early winner in the digital camera flash memory sweepstakes. It was the
most widely used form of digital camera flash memory. Type I cards (see
box below) currently store up to 512 megabytes.
Like many advanced technologies, CompactFlash is moving faster
that the terminology used to describe it. The CompactFlash
Association (CFA) is trying to standardize terminology to avoid
confusion and here are the terms they recommend until a final ruling
is made.
Note. CF+ originally referred to I/O cards such as modems,
Ethernet cards and so on, but in the digital camera storage area,
the IBM Microdrive is the only device that current warrants the name
(because it utilizes a high power (current) mode). The Lexar USB
Enabled CompactFlash card is sometimes referred to as a CF+ card
since it has a USB (I/O) interface added to the card. Using the CF+
terminology for these different types of cards does create problems,
so the CFA is working to develop recommended terminology that will
be useful to users.
SmartMedia cards
SmartMedia is the major competitor to CompactFlash and is used by a
number of leading camera companies. Like CompactFlash, SmartMedia is based
on an ATA architecture. The major advantage of SmartMedia is its
simplicity; it is nothing more than a flash chip on a card. It contains no
controllers and no supporting circuitry, which reduces the size of the
card as well as its manufacturing costs. The problem with this approach is
that the necessary controller functions must reside in the camera and
therefore compatibility with newer or older versions of the cards isn’t
guaranteed. A number of the first cameras using this storage medium had to
be returned to their manufacturers for upgrades when the next generation
of higher-capacity cards was released. These cards currently store up to
64 megabytes.
Sony Memory Sticks
Sony Corporation has developed a new form of flash memory called a
Memory Stick� that’s shaped something like a stick of gum. The current
versions have capacities of up to 64 Megabytes using currently available
flash chips, but capacity can be increased up to 256 Megabytes by 2001 as
denser chips become available.
MultiMedia cards
A MultiMediaCard weighs less than two grams and is the size of a
postage stamp. Targeted initially at the mobile phone and pager markets,
other markets including digital photography and MP3 music players have
started to take advantage of this solid-state data storage device that’s
about one-fifth the size of the popular CompactFlash memory
card.
Memory Card Storage
Cases
Cards are easy to misplace and the smaller they are, the easier they
are to lose. If you don’t find a way to store them safely, you’re sure to
run some through the washing machine forgotten in a shirt or pants pocket.
One way to keep them safe is to use an inexpensive storage case.
Magnetic disks
Instead of flash memory, which uses solid-state chips, some cameras are
designed to use magnetic disks, much like those used in your desktop
system.
Floppy disks
One of the oldest and cheapest storage media still in use is the
3�-inch floppy disk. You’d be hard pressed to find a computer system that
can’t read these disks. There is one digital camera that has chosen this
almost universally available media for its in-camera storage. Fitting a
fairly large floppy disk drive into a camera increases its size a little,
but the ready access to drives that can open and use the image files make
up for this one shortcoming. Almost all other types of storage require
special hardware or software on the machine before they’ll open your image
files. It’s the simplicity and universal usability of the floppy disk that
makes it so attractive.
It’s only been a matter of time before someone introduced cameras that
accepted the latest high-capacity floppy disks. Now they are beginning to
appear on the market.
Hard disks
One of the current drawbacks of compact flash memory cards is their
limited storage capacity. For high resolution cameras this is a real
drawback. One solution is high speed, high capacity hard disk drives.
Until recently, these drives were too large and expensive to be mounted
inside cameras, but that changed with IBM’s introduction of 1 Gigabyte,
340 Megabyte, and 170 Megabyte Microdrive hard disk drives. These drives
are smaller in volume and lighter in weight than a roll of film. In fact,
they are so small they can be plugged into a Type II CompactFlash slot on
a digital camera or flash card reader. (Type I CompactFlash slots are
thinner.) These drives will first appear in expensive professional
cameras, but eventually will drift down in price to a point where they can
be used in consumer cameras.
Another form of hard drive comes packaged in a Type III PC Card. A
newer Type IV card will be used for high capacity hard drives.
Clik! disk drive
Iomega’s Clik! drive uses a 40 megabyte 2-inch square disk. One version
of the Clik! drive is designed to provide additional storage in the field.
When your flash card is full, you can download the images to a battery
powered Clik! mobile drive. Back at your home or office, just place the
drive in its docking station that connects to the computers parallel port
and download the pictures to the computer.
Magneto Optical Disks
The iD-Photo disk that stores 730 MBytes has been developed by Olympus,
Sanyo and Hitachi-Maxwell. Expect cameras with this disk to begin
appearing very soon. Eventually, capacity may be increased to over 3.5
Gigabytes.
Optical discs
Although not yet adopted by a digital camera manufacturer, small
recordable optical discs much like the familiar CD are on their way.
DataPlay discs can hold 500 MB on a disc expected to cost somewhere around
$10. The disks, like CD-R discs are write-once but that ensures archival
quality with no danger of important files being deleted or written over.
- The capacity of the
storage device (expressed in Megabytes). - The resolution at which
the pictures are taken. - The amount of compression
used.
- They are erasable and
reusable. - They are usually
removable, so you can remove one and plug in another so storage is limited
only by the number of devices you have - They can be removed from
the camera and plugged into the computer or printer to transfer the
images. - Despite their similarities, they also have some significant
differences: - Magnetic disks have
moving parts while flash memory cards don’t. - Magnetic disks are
usually cheaper (per picture) and faster. - Flash memory cards are
smaller, lighter, and less prone to damage.
- PC Cards
- CompactFlash
- SmartMedia
- MemorySticks
- Multimedia Cards
- CompactFlash cards
and slots that are 3.3 mm thick are called CompactFlash
(abbreviated as CF) or CompactFlash Type I
(abbreviated as CF-I). Note that when there is no Type I or
Type II designation it implies a Type I device. - CompactFlash cards
and slots that are 5mm thick are called CompactFlash Type
II (abbreviated as CF-II). - Lexar USB enabled
CompactFlash cards are referred to as USB Enabled
CompactFlash. - IBM Microdrives are
referred to as CF+ Type II Microdrive (abbreviated as
CF+/II Microdrive).
| Storage Media Types
Compact Flash Terminology |