Digital Camera
Technology is Making Film Obsolete
How is a digital camera different from a film camera? What are pixels and why are they important? What’s
the difference between optical and digital zoom? What advantages do digital
cameras have compared to film cameras? This article will address these and other questions
as we discuss digital camera technology.
First a short history
and overview of digital imaging…
The technology began with
television in the early 1950’s when researchers discovered how to convert video
images to electrical signals for storage on magnetic tape. In the 1970's
electronic still photo cameras were developed. These employed the first
generations of solid-state image sensors. By the late 1980's megapixel sensors
were introduced - the technology that paved the way to today's modern digital
cameras.
Fundamentally, film and
digital cameras do the same thing. Both utilize camera lenses to focus
photographic images on a light sensitive medium where they are stored for later
retrieval. But the way each camera does this is radically different.
Instead of capturing the image
on film that must be developed and printed, digital cameras measure light and
color characteristics using photodiodes built into a sensor - either a Charged
Coupled Device (CCD) or Complementary Metal-Oxide Semiconductor (CMOS). An
Analog-to-Digital Converter (ADC) then converts the signal to binary, or
digital, code. This code is sent to a Digital Signal Processor (DSP) which
adjusts photographic elements such as contrast and color, and compresses the
file for storage in the camera’s memory, compact flash card, or other memory
device.
Digital
cameras have huge advantages when it comes to viewing and printing photos. It's
nearly instantaneous! We can immediately look at the picture on the camera's LED
screen, and if we don’t like it, delete it and shoot again. Or we download and
view it on our computer's monitor. And the pictures can be cropped or enhanced
in minutes on the computer with
photo software and printed with a photo printer.
Plus many digital cameras have optional printer docks that don't require a
computer at all.
What’s a Pixel?
The human eye perceives a
nearly infinite blending of light and color which high-quality film can
approximate in a photograph. A digital image however, is a binary code file that
records these variations as elements called pixels - short for picture elements.
Pixels are tiny squares of
light and color, that when assembled create a mosaic. And like a mosaic, if the
squares are small enough we see a smooth, photographic image. However, if the
pixels are too big the transitions appear jagged or out of focus.
More pixels equal higher
resolution and photos with clearer sharper detail, much like when you look at a
mosaic with very small elements. For example, a 3 Megapixel digital camera can
produce pretty good snapshots and even enlargements to about 8” X 10”. But the
more you enlarge, crop or otherwise manipulate the image, the larger the pixels
become, degrading the photo’s quality.
Size Really
Does Matter
The number of pixels the sensor
produces is important, but so is the quality. The sensors of many compact
digital cameras are smaller than a fingernail, while some larger
models will feature sensors up to about 1” across. There are conflicting
opinions about sensor type and size, and the technology is advancing. But in
general it can be argued that the photodiodes in a tiny CCD probably won’t be as
powerful or effective as an equal number in a larger sensor.
So unless your most important
considerations are the smallest and/or cheapest camera, you’re likely to be
happier with the picture quality from a slightly larger model, assuming both
have the same number of pixels.
All Zooms are not equal
The specs say the camera has 3X
optical and 4X digital for a 12X total zoom. Sounds good, right? The answer is
yes and no. Optical zoom works like a telescope, while digital zoom crops the
picture. Using these zoom specs with our 3 megapixel camera example, here’s what
happens.
Optical zoom brings the image
3X closer and uses all 3 million pixels. But digital zoom crops up to 75% of
what the lens sees and the sensor is exposed to, so the photo now has about
750,000 pixels. Depending on lighting and other conditions, using full digital
zoom may not even get you a good 4” X 6” print.
The last few years have seen
tremendous advancement in digital imaging technology. Some high-end digital
cameras can now generate more than 12 million pixels and produce photos that
rival medium-format film cameras. As with all electronic technology, it’s
reasonable to expect even better cameras will come to the market over the next
several years.
Photography “purists” will
probably resist abandoning their film cameras as long as possible. But when
comparing convenience, flexibility and quality, it seems inevitable that the
majority of photographers will opt for digital over film photography – and
probably sooner rather than later.
For more information on
comparing features and finding the best digital camera to fit your photography
style and budget, see
Digital Camera Comparisons.
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