How do digital cameras work?
In contrast to a conventional film camera, in a digital camera the light is focused onto an image sensor called a CCD (charge coupled
device). The CCD is a collection of light-sensitive photosites that produce an electric charge when struck by light. These charges are
converted into numbers that are stored in the memory (usually on a memory chip). From there, the whole image can be displayed, sent to a
computer, or even printed directly on a printer.
Who are the biggest digital camera manufacturers and what cameras do they make?
Is the digital zoom important?
No, it is not. Unlike optical zoom, only some of the light sensors are used to produce an image when the digital zoom is used, producing
a lower-quality picture. The same effect can be achieved by using the zoom in the image-processing software. The digital zoom is a marketing
gimmick allowing digital camera manufacturers to claim a higher zoom factor than their cameras can really achieve.
Is the image stabilization important?
The image stabilization is very important when choosing a camera with a high optical zoom factor (>4). Without this feature, most
pictures taken while zooming in, or at longer exposure times, and holding the camera in your hand will be blurred. Note that almost all
digital camcorders have image stabilization.
What resolution do I need for high quality pictures?
For 4 inch by 6 inch pictures, you need at least 0.9 megapixels. For 5x7 prints, you need at least 1.3 megapixels. For 8x10 prints, you
need at least 3.0 megapixels. For 8.5x11 prints, you need at least 3.5 megapixels. For putting up pictures on web sites, a 2.0 megapixel
camera should be enough.
Will my printer be able to handle high-resolution digital photos?
With a relatively new printer, the resolution should not be a concern. However, you should consider a "photo" printer since
they are specifically made for printing pictures and are generally considered to produce better pictures. You will need glossy paper and a
paper cutter to cut out the pictures (faster and much more accurate than scissors).
What is the cost of printing pictures?
The main costs of printing your own pictures are the costs of the printer ink and of glossy photo paper. The major advantage of digital
cameras is the ability to take multiple pictures at no extra cost and then printing only the best ones. Some traditional film developers (Walmart
and Costco) have started offering printing of digital photos at about the same prices as their conventional film development. There are also
online companies that can print out uploaded pictures and send them back to you by mail.
What is ISO speed?
This setting has been adopted from film cameras. It refers to the film's sensitivity to light. Higher ISO speeds are needed to take
pictures in worse lighting conditions, however they also cause an increased amount of noise. 100 ISO is the default. At 400 ISO the noise is
easily detectable on most cameras.
What is lens aperture?
Lens aperture or the f-number is the ratio of the focal length of the lens to the diameter of the light rays passing through the aperture
in the iris diaphragm. Smaller numbers represent bigger openings and allow more light to pass through. F-number settings are adjustable;
lenses are marked with their maximum aperture (lowest f-number).
What is shutter speed?
Shutter speed is the amount of time the shutter allows light onto the CCD. The shutter speed is measured in seconds (or fractions of a
second for most common pictures). The slower the shutter speed, the more motion is recorded by the camera. A tripod might be needed to use
slower shutter speeds without blurring the picture.
How does aperture affect depth-of-field?
Larger aperture (smaller f-number) produces shallower depth of field. Depth of filed affects how far away from the focus point the
objects can be before they become increasingly blurred in the resulting picture.
What are aperture and shutter priority modes?
In aperture priority mode, you manually choose the aperture setting and the camera adjusts the shutter speed. This mode is mainly used to
control the depth-of-field. Correspondingly, in the shutter priority mode, you choose the shutter speed and the camera chooses the right
What is auto bracketing?
Auto bracketing is a mode in which the camera takes a number of successive shots of the same scene at slightly different exposures. This
makes sure that one of the shots comes out looking good, even if you are don't know what exposure setting is the best.
What accessories do I need?
One major upgrade needed by almost all digital cameras is a higher capacity memory card. You should buy as large a memory card as your
camera can accept, as the memory cards that are included with the cameras are usually not nearly big enough to hold a good number of high
quality pictures. Other accessories worth considering are a battery charger, rechargeable batteries, tripod, and a camera case. Best prices
on accessories are rarely offered with the cameras - many retailers compete on the price of cameras, hoping to make big markups on
What types of storage are used in digital cameras?
Two popular memory card types are CompactFlash™ and SmartMedia™ cards. Most new cameras can accept CompactFlash™ up to 256 or 512
MB or SmartMedia™ cards up to 128 MB. Both types of memory are similar in price and performance but CompactFlash™ cards are more widely
used. Other possibilities include Sony Memory Stick (smaller and more expensive compared to memory cards), built-in hard disks (more
expensive, very large capacity), CD-Rs (increase the camera size), or DVD-Rs (also big). The type of storage has no effect on picture
How many pictures will fit in the memory?
The exact number depends on the size of the memory card (or other type of storage used), the camera's resolution, the compression quality
setting, the exact type of camera, and even the type of pictures taken. For example, a 3 megapixel camera might make 0.8 MB pictures at the
highest JPEG quality setting, therefore fitting about 160 pictures on a 128 MB card.
What is it with the Foveon X3™ technology?
Foveon developed a new type of image sensors that can capture full red, green, and blue light at each sensor. The sensors in conventional
digital cameras have to use mosaic color filter array because they only detect one color per location. Foveon's patented X3™ technology
should improve the sharpness and quality of pictures if it can be produced cheaply enough to be competitive with traditional CCD sensors. It
is not yet used in any quality consumer-level cameras.
Why is the advertised megapixel resolution higher than my picture resolution?
The camera does have as many sensors as claimed, however not all of them are used to capture color info.
What is JPEG and TIFF?
Two most popular picture storage formats used by digital cameras are JPEG and TIFF. The JPEG format uses lossy compression (some data
judged by the algorithm to be less important to the human viewer is discarded) to achieve small file sizes. The TIFF format uses lossless
LZW compression so no information is lost, however the pictures are typically much larger. High-quality JPEG setting is preferable for most
What is it with quality settings on cameras?
You should make sure to read your camera's manual before taking pictures at low quality settings. At those settings, the camera may store
images at lower resolutions or use very high JPEG compression levels, resulting in lower quality pictures and negating the purpose of paying
for a high-resolution digital camera. If you can't fit enough pictures in the memory, you should buy a higher capacity memory card instead.
What batteries are used in digital cameras?
The flash and the LCD display use a lot of battery power. For this reason most digital cameras need rechargeable batteries. Some cameras
come with chargers. Many cameras that take rechargeable NiMH AA batteries can use regular alkaline batteries in an emergency.
What are smart chargers?
Smart chargers can turn themselves off when the batteries are done charging.
What are OLED displays?
OLED is a new type of display technology meant to replace LCD screens used to preview pictures. The major advantage of OLED is that they
glow only when needed, using less battery power. They also don't need a layer of filters and shutters as do LCD screens, making them
brighter when viewed from an angle. Their main current disadvantage is a shorter life span and degradation over time when used.
What is red-eye reduction?
Red-eye effect occurs when the pupils of people's eyes appear to be red in a picture. This effect can be prevented by using the camera's
feature of shining the light before a picture is taken, asking the subjects not to look directly at the camera, or using the photo-editing
software's red-eye removal feature.
What are SLR digital cameras?
In an SLR (Single Lens Reflex) camera, the user is seeing exactly what the camera is seeing through a series of prisms and mirrors. This
becomes important for more advanced photographers. In SLR cameras, it is also possible to interchange lenses and keep the lenses from other
cameras. Many digital SLR cameras also offer higher resolution since they are aimed at the pros. The disadvantages of SLR digital cameras
are the significantly higher costs, bigger size and weight, and a small delay before the photo is taken because the mirror has to move out
of the way before a shot.
What are NiMH batteries?
The NiMH (Nickel Metal Hydride) batteries are the most popular type of rechargeable batteries used in digital cameras. A higher mAh value
(ex. 1700) means a proportionally longer life before the recharge is needed. Most NiMH batteries can be recharged up to 300-1000 times.
There is no need to wait for these batteries to be completely discharged before recharging them. There is not much difference between
brands. Rechargeable NiMH batteries slowly discharge themselves when sitting unused.
What about MPEG movie modes in digital cameras?
Many digital cameras offer the ability to shoot short movies that are saved in the MPEG formats. Unfortunately, the quality of these
movies doesn't come close to the movies shot with a camcorder. They are often severely limited in terms of length. Some cameras also don't
Are manual controls important?
Automatic settings can work for amateur photographers in a majority of cases. However, once a few pictures come out underexposed or
blurred with auto settings, the manual controls become necessary.
What is a shutter lag?
Almost all consumer-level digital cameras suffer from a rather long (about 1 second) delay before the picture is taken after the shutter
button is pressed. This is a big problem when taking shots of fast-moving subjects, for example in sports. On many cameras this delay can be
reduced by half-pressing the button before the shot to focus the camera on the subject.
What is a macro setting?
The macro setting improves the quality of close-up pictures (for example when photographing documents).
What are gray-market cameras?
Many deep-discount online dealers offer gray-market cameras. These cameras have been made for markets outside US and imported into US for
sale without the permission of their manufacturers. The main issue with these cameras is the possible lack of warranty.
What should I worry about when buying from a lowest-cost online dealer?
You should be prepared for such a dealer to push warranties or accessories, usually at higher prices than you could buy them for
elsewhere. There is small possibility that a camera is a gray-market one or refurbished. There might be a longer wait if the dealer doesn't
keep the camera in stock.
What is a fast lens?
Fast lens means lower f/value, which corresponds to larger aperture size. For example, f/2.0 is a fast lens. Fast lenses allow use of
lower ISO settings or higher shutter speeds for pictures without flash, producing sharper images. Faster is better.
Does CCD size matter?
In general, the larger CCD means a bigger light-collecting area and therefore better performance in low-light conditions with less noise.
However, this rule is very inexact and it doesn't hold in many cases. The trend is to lower the CCD size because it also lowers the costs.
Do digital cameras have better quality than film cameras?
Newer high-resolution digital cameras (6+ MP) approach and exceed the quality of the 35mm SLR film cameras. Price to quality ratio is
still better for film cameras but the digital cameras offer many benefits such as instant previews, no cost to additional photos, computer
photo editing, or private printing that film cameras cannot match.
How to move pictures from the camera to the computer?
Most cameras use the USB 1.1 standard cable for uploading the pictures. Some support USB 2.0 or FireWire (IEEE-1394) for faster uploads.
Of course, cameras that can save pictures on CDs don't need a cable.
Will an airport X-Ray scanner erase my pictures on a digital camera card?
No, the chance of this happening is very remote.
Is the CRT or the LCD flat panel monitor better for viewing digital camera pictures?
A traditional CRT monitor is better due to limitations of color representation by currently available LCD monitors.