Digital Cameras & Digital Photography

Brian Lee asked:


Resolution

The amount of detail that a camera can capture is called the resolution, and it is measured in pixels. The more pixels a camera has, the more detail it can capture and the larger pictures can be without becoming blurry or “grainy.” High-end consumer cameras can capture over 12 million pixels. Some professional cameras support over 16 million pixels (megapixels), or 20 million pixels for large-format cameras. For comparison, it has been estimated that the quality of 35mm film is about 20 million pixels.

Exposure and Focus

Just as with film, a digital camera has to control the amount of light that reaches the sensor. The two components it uses to do this, the aperture and shutter speed, are also present on conventional cameras.

Aperture: The size of the opening in the camera. The aperture is automatic in most digital cameras, but some allow manual adjustment to give professionals and hobbyists more control over the final image.

Shutter speed: The amount of time that light can pass through the aperture. Unlike film, the light sensor in a digital camera can be reset electronically, so digital cameras have a digital shutter rather than a mechanical shutter.

These two aspects work together to capture the amount of light needed to make a good image. In photographic terms, they set the exposure of the sensor.

In addition to controlling the amount of light, the camera has to adjust the lenses to control how the light is focused on the sensor. In general, the lenses on digital cameras are very similar to conventional camera lenses — some digital cameras can even use conventional lenses. Most use automatic focusing techniques.

The focal length, however, is one important difference between the lens of a digital camera and the lens of a 35mm camera. The focal length is the distance between the lens and the surface of the sensor. Sensors from different manufacturers vary widely in size, but in general they’re smaller than a piece of 35mm film. In order to project the image onto a smaller sensor, the focal length is shortened by the same proportion.

Focal length also determines the magnification, or zoom, when you look through the camera. In 35mm cameras, a 50mm lens gives a natural view of the subject. Increasing the focal length increases the magnification, and objects appear to get closer. The reverse happens when decreasing the focal length. A zoom lens is any lens that has an adjustable focal length, and digital cameras can have optical or digital zoom — some have both. Some cameras also have macro focusing capability, meaning that the camera can take pictures from very close to the subject.

Digital cameras have one of four types of lenses:

1) Fixed-focus, fixed-zoom lenses - These are the kinds of lenses on disposable and inexpensive film cameras — inexpensive and great for snapshots, but fairly limited.

2) Optical-zoom lenses with automatic focus - Similar to the lens on a video camcorder, these have “wide” and “telephoto” options and automatic focus. The camera may or may not support manual focus. These actually change the focal length of the lens rather than just magnifying the information that hits the sensor.

3) Digital-zoom lenses - With digital zoom, the camera takes pixels from the center of the image sensor and interpolates (alters) them to make a full-sized image. Depending on the resolution of the image and the sensor, this approach may create a grainy or fuzzy image. You can manually do the same thing with image processing software — simply snap a picture, cut out the center and magnify it.

4) Replaceable lens systems - These are similar to the replaceable lenses on a 35mm camera. Some digital cameras can use 35mm camera lenses.

Storage of Images

Most digital cameras have an LCD screen so you can view your picture right away. This is one of the great advantages of a digital camera — you get immediate feedback on what you capture. Of course, viewing the image on your camera would lose its charm if that’s all you could do. You want to be able to load the picture into your computer or send it directly to a printer. There are several ways to do this.

Although most of today’s cameras are capable of connecting through serial, parallel, SCSI, USB, or FireWire connections, they usually also use some sort of removable storage device. Digital cameras use a number of storage systems. These are like reusable, digital film, and they use a caddy or card reader to transfer the data to a computer. Many involve fixed or removable flash memory. Digital camera manufacturers often develop their own proprietary flash memory devices, including SmartMedia cards, CompactFlash cards and Memory Sticks. Other removable storage device include floppy disks, hard disks (external, or microdrives), and writeable CD’s and DVD’s.

Regardless of what type of storage they use, all digital cameras need lots of room for pictures. They usually store images in one of two formats — TIFF, which is uncompressed, and JPEG, which is compressed. Most cameras use the JPEG file format for storing pictures, and they sometimes offer quality settings (such as medium or high).

To make the most of their storage space, almost all digital cameras use some sort of additional data compression to make the files smaller. One compression routine takes advantage of patterns that repeat. The image can be reconstructed exactly as it was recorded, reducing the file size no more than 50%, often much less. Another compression routine called irrelevancy eliminates some of the more meaningless data, taking advantage of the fact that digital cameras record more information than the human eye can easily detect.

Brooke Yan asked:


Digital cameras, which employ reusable memory cards instead of film, give you far more creative control than film cameras can. With a digital camera, you can transfer shots to your computer, then crop, adjust color and contrast, and add textures and other special effects. Final results can be made into cards or T-shirts, or sent via e-mail, all using the software that usually comes with the camera. You can make prints on a color inkjet printer, or by dropping off the memory card at one of a growing number of photofinishers. You can upload the file to a photo-sharing Web site for storage, viewing, and sharing with others.

Like camcorders, digital cameras have LCD viewers. Some camcorders can be used to take still pictures, but a typical camcorder’s resolution is no match for a good still camera’s.

WHAT’S AVAILABLE

The leading brands are Canon, Fujifilm, HP, Kodak, Olympus, and Sony; other brands come from consumer-electronics, computer, and traditional camera and film companies.

Digital cameras are categorized by how many pixels, or picture elements, the image sensor contains. One megapixel equals 1 million picture elements. A 3-megapixel camera can make excellent 8×10s and pleasing 11×14s. There are also 4- to 8-megapixel models, including point-and-shoot ones; these are well suited for making larger prints or for maintaining sharpness if you want to use only a portion of the original image. Professional Digital cameras use as many as 14 megapixels.

Price range: $200 to $400 for 3 megapixels; $250 to $400 for 4 and 5 megapixels; $300 to $1,000 for 6 to 8 megapixels.

IMPORTANT FEATURES

Most Digital cameras are highly automated, with features such as automatic exposure control (which manages the shutter speed, aperture, or both according to available light) and autofocus.

Instead of film, digital cameras typically record their shots onto flash-memory cards. CompactFlash and SecureDigital (SD) are the most widely used. Once quite expensive, such cards have tumbled in price–a 128-megabyte card can now cost less than $50. Other types of memory cards used by cameras include Memory Stick, Smart Media and xD-picture card. A few cameras, mainly some Sony models, use 3 1/4-inch CD-R or CD-RW discs.

To save images, you transfer them to a computer, typically by connecting the camera to the computer’s USB or FireWire port or inserting the memory card into a special reader. Some printers can take memory cards and make prints without putting the images on a computer first. Image-handling software, such as Adobe Photoshop Elements, Jasc Paint Shop, Microsoft Picture It, and ACDSee, lets you size, touch up, and crop digital images using your computer. Most digital cameras work with both Windows and Macintosh machines.

The file format commonly used for photos is JPEG, which is a compressed format. Some cameras can save photos in uncompressed TIFF format, but this setting yields enormous files. Other high-end cameras have a RAW file format, which yields the image data with no processing from the camera.

Digital cameras typically have both an optical viewfinder and a small color LCD viewer. LCD viewers are very accurate in framing the actual image you get–better than most of the optical viewfinders–but they use more battery power and may be hard to see in bright sunlight. You can also view shots you’ve already taken on the LCD viewer. Many digital cameras provide a video output, so you can view your pictures on a TV set.

Certain cameras let you record an audio clip with a picture. But these clips use additional storage space. Some allow you to record limited video, but the frame rate is slow and the resolution poor.

A zoom lens provides flexibility in framing shots and closes the distance between you and your subject–ideal if you want to quickly switch to a close shot. The typical 3x zoom on mainstream cameras goes from a moderately wide-angle view (35mm) to moderate telephoto (105mm). You can find cameras with extended zoom ranges between 8x and 12x, giving added versatility for outdoor photography. Other new cameras go down to 24 or 28 mm at the wide-angle end, making it easier to take in an entire scene in close quarters, such as a crowded party.

Optical zooms are superior to digital zooms, which magnify the center of the frame without actually increasing picture detail, resulting in a somewhat coarser view.

Sensors in digital cameras are typically about as light-sensitive as ISO 100 film, though some let you increase that setting. (At ISO 100, you’ll likely need to use a flash indoors and in low outdoor light.) A camera’s flash range tells you how far from the camera the flash will provide proper exposure: If the subject is out of range, you’ll know to close the distance. But digital cameras can tolerate some underexposure before the image suffers noticeably.

Red-eye reduction shines a light toward your subject just before the main flash. (A camera whose flash unit is farther from the lens reduces the risk of red eye. Computer editing of the image may also correct red eye.) With automatic flash mode, the camera fires the flash whenever the light entering the camera registers as insufficient. A few new cameras have built-in red-eye correction capability.

Some cameras that have powerful telephoto lenses now come with image stabilizers. These compensate for camera shake, letting you use a slower shutter speed than you otherwise could for following movement. But an image stabilizer won’t compensate for the motion of subjects.

Most new 6- to 8-megapixel cameras come with full manual controls, including independent controls for shutter and aperture. That gives serious shutterbugs control over depth of field, shooting action, or shooting scene with tricky lighting.

HOW TO CHOOSE

The first step is to determine how you will use the camera most of the time. Consider these two questions:

How much flexibility to enlarge images do you need? If you mainly want to make 4×6 snapshots, a camera with a 3- or 4-megapixel resolution will be fine. Such a camera will also make an 8×10 print of an entire image without alteration that looks as sharp as one from a 6- or 8-megapixel model. But to enlarge the image more or enlarge only part of it, you’ll want a 6- to 8-megapixel camera.

How much control do you want over exposure and composition? Cameras meant for automatic point-and-shoot photos, with a 3x-zoom lens, will serve snap shooters as well as dedicate hobbyists much of the time. The full-featured cameras in the 6- to 8-megapixel range offer capabilities that more-dedicated photographers will want to have. Two of the more important capabilities are a zoom range of 5x to 10x or more, which lets you bring distant outdoor subjects close and also lets you shoot candid portraits without getting right in your subject’s face, and a full complement of manual controls that you determine the shutter speed and lens opening. ‘

Once you’ve established the performance priorities that you need from a camera, you can narrow your choices further by considering these convenience factors:

Size and weight. The smallest, lightest models aren’t necessarily inexpensive 3-megapixel cameras. And the biggest and heaviest aren’t necessarily found at the high end. If possible, try cameras at the store before you buy. That way, you’ll know which one fits you hand best and which can be securely gripped. In our tests, we have found that some of the smallest don’t leave much room even for small fingers.

Battery type and life. All digital cameras can run on rechargeable batteries of one of two types: an expensive battery pack or a set of AA batteries. In our tests of the cameras, neither battery type had a clear performance advantage. The best-performing cameras offer upward of 300 shots on a charge, while the worst manage only about 50. We think it’s more convenient to own a camera that accepts AA batteries. You can buy economical, rechargeable cells (plus a charger) and drop in a set of disposable lithium or alkaline batteries if the rechargeable run down in the middle of the day’s shooting.

Camera speed. With point-and-shoot cameras like the ones we tested, you must wait after each shot as the camera processes the image. Most models let you shoot an image every few seconds, but a few make you wait 5 seconds or more. They may frustrate you when you’re taking photos in sequence.

Your other cameras. If you’re adding a camera to your lineup or trading up to a more versatile model, look first for one that’s compatible with the other cameras. If it is, you can share memory cards and batteries. Designs within a camera brand line are often similar. So staying wit the brand you have lowers the learning curve on the new camera for family members who switch between cameras.

Copyright © 2002-2006 Consumers Union of U.S., Inc.

For the latest information on this and many other products and services, visit www.ConsumerReports.org.



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michael wong asked:


The simplified version of how the camera works is that it uses lens to focus light on photosensor. Most compact digital camera use charge-coupled device (CCD) as photosensor. When light strikes the sensor, it will record the image electronically and transfer it for organization. After that, it will convert the image into binary digital data and stored in memory.

In order to get an ideal photograph, the amount of light reaching the photosensor must be controlled carefully. To achieve that, you need to control the shutter speed and the aperture size. And to make things easier for you, the compact digital camera manufacturers have set the shutter speed electronically and set the aperture size on automation.

Megapixel plays an important role on the quality of your picture. It is related to the amount of details in your picture. So, the more megapixels you have the more detail you will have on your image.

You can see that cameras nowadays come with optical zoom and digital zoom. Optical zoom is more important because it actually zooms into your subject while digital zoom only enlarges your picture. That is why sometimes you will get fuzzy picture with digital zoom.

Cameras today also come with LCD screen for you to preview the picture you took. Don’t misunderstand that the digital camera is compact and the LCD screen will be small. It depends on how the manufacturer fir the screen to the camera.

If you have a digital camera back in the early days, you should remember that the storage device was built into the camera. That gave some frustration to some photographer because you need to clear the pictures when the memory is full. Luckily, as the technology evolves, you can now enjoy portable memory storage.

You can now store your pictures into memory devices like SD cards or smart media cards. When the memory is full, you can just label the memory device and keep it as your album. Furthermore, memory device nowadays come in different sizes. The storage amount of the memory device depends on the quality of your picture and how frequent you take photograph.

michael wong asked:


Although photography has been in the market for quite some time, some people still ask “how much it’s going to cost me?”, “what a digital camera can do?” and “why do I need photography?”

Let’s look at each of them in detail:

As digital photography is getting more popular, things are going to get cheaper. One of the reasons is that manufacturers are competing for market share and they are more likely to launch cheaper cameras with more functions. Just look at the compact digital camera in the market now, you can get a camera with at least 9 megapixels and 10x optical zoom at the price of less than $300. Even the DSLR cameras nowadays are getting more and more affordable.

Also when competitions are getting stronger, manufacturers will try to make cameras with as many features as possible. It is like an unwritten rule that compact digital cameras nowadays must be able to record video and audio. When you launch a point and shoot camera without this feature, your potential clients might not even want to look at it.

Also some digital cameras nowadays are equipped with sophisticated editing software and touch screen capability. You can now add stars, fog it up or add other whacky stuffs on the camera.

Since you can operate your camera with touch screen, you can expect that one day, you will see the LCD screen big enough to occupy the back of your camera. Can you imagine how much fun it is to look at your pictures in such a big screen and it will be more breath taking when the manufacturers throw in wide angle lens together.

Now, when you are going into digital photography, it is only logic that you have a digital camera. Photography is more than a hobby. It is about keeping the memory of that special moment. You want to remind yourself that you were once there at that period. You want to be able to show your child that you were young once and how life was back then. It is a different experience when you look back at your photos 10 years ago. Go have a look at them now.