Foundation
Digital images are formed from tiny dots of red, green and blue color. The dots, usually many millions per image, blend into the smooth continuous tones we’re so familiar with from film. These images are captured directly with digital cameras, or by scanning a transparency, negative, or print. The end result is an image in a universal format that can be easily manipulated, distributed, and used. This digital format for images, and the development of the Internet in particular, have opened exciting new vistas for photography, which we'll explore in this class.
It was only a few short years ago, around 1995, when digital photography appeared on the scene for most of us. In that year, Apple's Quick-Take 100 and Kodak's DC4o both broke the $1000 barrier for digital cameras. These film less cameras captured very small images, but they were immediate hits. Small businesses, realtors, insurance agents, and other early adopters snapped them up. They were so popular that the early models were soon followed by a steady stream of digital cameras from Casio, Soney, Olympus and others. The race was on and the stream of new cameras not only continues, it accelerates. Things have advanced so far that the same money that would have bought one of those early cameras will now buy one that captures images 20 times larger and has many more features such as video sound, and professional style controls.
These cameras weren't developed in isolation. Professional cameras based on film cameras with image sensors added to capture digital images, were growing in popularity among professionals. However, their high prices, often $20,000 or more, made these cameras available only to an elite few. Kodak had also already introduced the Photo CD process where they inexpensively scanned slides and negatives into a digital format. The process caught on with professionals, but not with amateurs as Kodak had hoped. Meanwhile, publishing, advertising, medicine, and many other fields were going digital. Digital images slipped easily into this trend because they could be instantly displayed, e-mailed, and inserted into documents. It was professional who led the change from film to digital, but it wasn't long before many more of us were headed in the same direction. Film is no longer just a mature industry it's dying. Given the scale of this change, how did it all come to pass?
Digital cameras come in all shapes and sizes and no one yet knows what a digital camera should look like. 35mm cameras have taken familiar forms because form follows function and they require room for the film and light path as well as prisms and such. Digital cameras are freed of many of these limitations so they can take new forms. During these early days, some companies make their cameras look like familiar 35mm cameras while others veer off in new directions. Increasingly cameras are even built into other devices such as cell phones and digital camcorders. Regardless of how digital cameras look, the market for them is roughly divided into categories with blurry lines separating cameras based mainly by image size, features, and Of Course, price.
POINT AND SHOOT CAMERAS
For the past few decades, serious photographers have mainly been using traditional 35mm SLR cameras. But these large and heavy cameras are inconvenient to say the least, so most serious photographers have always stuck a point and shoot camera in their shirt pocket. The photos from these small cameras may not be quite as good (and that is debatable), but they go anywhere, and pictures that would otherwise be missed are captured. These cameras are fully automatic and usually don't provide you with every possible creative control-that's why they are called "point and shoot." Point and shoot cameras have earned their stripes and are welcome additions to even the most professional photographer's camera collection. Increasingly, point and shoot cameras are being embedded in mobile devices such as camera phone, smart phones and personal digital assistants (PDAs). These embedded cameras, once almost toy-like, are rapidly moving up the quality ladder with 3 megapixel sizes available in some parts of the world.
ADVANCED AMATEUR CAMERAS
Positioned just above the point and shoot cameras is a family of cameras with larger image sizes and more advanced features. These cameras appeal to serious photographers who like to have more creative control of their camera's settings and make larger prints. Because their features appeal to both experienced amateurs and professionals, they are sometimes called prosumer cameras. With these cameras you have as much, or more, creative control as you do with 35mm SLR cameras.
PROFESSIONAL CAMERAS
At the highest end of the spectrum are the professional digital cameras including digital versions of professional 35mm SLR film cameras. One huge advantage these cameras have is that they accept most of the accessories such as lenses and flash units designed for the film versions. They also work much the same way as the film version, so if you are familiar with that version there is less to learn.
Large format cameras used by most studio and a few nature photographers have also gone digital. In most cases you can switch between digital and film just by switching the camera's back. A digital back can replace the film magazine on a medium format camera and slide into the back of a 4 x 5 or larger camera just like a film holder. These digital backs come in two basic forms: linear and area arrays.
Linear array backs scan the image much like a scanner scans a page. The image gets built up one line at a time. The time it takes to scan an image makes these backs suitable only for static subjects under continuous illumination nation. Scan backs usually use three strips of CCDs (called a trilinear array) also it can capture a full color image in one scan.
Area arrays are like the CCDs in consumer digital cameras and capture full color images instantaneously. A few cameras use three separate image sensors, each with its own colored filter that captures just red, green, or blue light.
Generally, you can get good results from any camera, provided it has the features you need.THINGS TO CONSIDER
Image size or resolution is often overrated. Generally the larger the image a camera can capture, the sharper it will be when enlarged. However, most images are reproduced in print at between 200-300 pixels per inch so even less expensive cameras will give good 4 x 6 inch prints. Images on the Web are normally displayed at less than 100 pixels per inch, so you can get good results with images that are quite small.
Image quality is determined by the amount of compression and the file format used. Normally, cameras capture JPEG images in a variety of compressions. A few cameras also let you shoot in higher quality, uncompressed formats such as TIFF or RAW.
Storage media varies widely and the kind you use doesn't matter a great deal, with one exception. If you have more than one digital camera, or other digital device that uses storage media, it's nice to have them use the same kind so you don't need to buy more then one kind of media.
Lenses can make a huge difference. If the camera has a built-in zoom lens, its zoom range is important as is it's maximum aperture. Larger, and more expensive SLR cameras often have interchangeable lenses. The lens also determines how close you can get to a subject, or how far away.
Auto focusing doesn't always work the way you like; so manual focus is a nice feature to have.
Autoexposure is available on every camera but aperture and shutter priority modes are nice to have. Exposure compensation lets you lighten or darken images when automatic exposure doesn't work the way you want. Histograms let you analyze your results with more precision.
Macro mode lets you get closer to small subjects or capture fine details on larger ones.
Hot shoes let you mount a more powerful and flexible external flash on the camera. There are also other ways to connect a flash or strobes.
AC adapters let you keep the camera on all of the time without it going into sleep mode or running down the batteries. These are ideal when using the camera to give a slide shows.
A monitor lets you review your images as soon as you shoot them. The best monitors swivel and tilt so you can shoot with the camera held above your head or close to the ground.
Video out connections lets you connect your camera to a TV set so you can see larger versions of the images as you shoot them.
A self-timer or a remote control lets you trigger the shutter without shaking the camera and blurring the images.
Video modes let you capture short video clips that you can play back on the computer or integrate into slide shows.
A diopter adjustment lets you adjust the viewfinder so you don't need glasses when composing images.
All digital cameras have an automatic mode that sets focus and exposure for you. With the camera set to this mode, all you have to do is frame the image and push the shutter button. You'll find that this mode is great in the vast majority of situations because it lets you focus on the subject and not on the camera.
Here are some things to expect with almost all digital cameras.
Getting ready.
Turn the camera on and set it to auto mode. To conserve your batteries, turn off the monitor and compose your image through the optical viewfinder. If the camera has a lens cap, be sure to remove it.
Holding the camera. To take pictures, hold the camera with your right hand while supporting the lens with your left. Be sure not to block the flash autofocus port, or lens.
Framing the image. Viewfinder shows you the scene you are going to capture although most show only about 95% of the scene. If your camera has a zoom lens, you can zoom it in and out by pressing a button or lever or by turning a ring on the lens. Zooming out widens your angle of, view and zooming in enlarges subjects. If the image in the viewfinder is fuzzy, see if the camera has a diopter adjustment dial you can use to adjust it.
Autofocus. Compose the image in the viewfinder making sure the subject that you want sharpest is in the focus area in the center of the viewfinder. Some cameras have more than one autofocus point indicated in the viewfinder or on the monitor and will focus on the closest part of the scene covered by one of the points. This lets you easily focus on a subject that isn't in the exact center of the viewfinder.
Autoexposure measures light reflecting from parts of the scene and uses these readings to set the best possible exposure. This happens at the same time focus is locked-when you press the shutter button halfway down.
Autoflash. If the light is too dim, the autoexposure system will usually fire the camera's built-in flash to illuminate the scene. If the flash is going to fire, it pops up or a flash lamp glows when you press the shutter button halfway down. If the flash lamp blinks when you press the shutter button halfway down, the flash is charging. Release the shutter button for a few seconds and try again.
Automatic white balance. Because the color cast in a photograph is affected by the color of the light illuminating the scene, the camera automatically adjusts color balance to make white objects in the scene look white in the photo.
Taking the picture. The shutter button has two stages. When you press it halfway down, the camera locks focus and exposure and the camera beeps or an indicator lights up when this happens. (If the indicator blinks, it means the camera is having trouble focusing.) After focus and exposure are locked, press the shutter button all the way down to take the picture. When you do so, the camera may beep. As you take photos, they are first stored in the camera's internal memory called a "buffer." When the buffer is full you'll have to wait until one or more of the images has been transferred to the memory card before taking any more pictures.
Quit. When finished taking pictures, turn the camera off to conserve battery Power.
To operate a digital camera you use buttons and menus. When reading about digital photography you'll often encounter the term mode. This basically means the same as a setting. Many cameras have a small control panel that displays the current camera settings and how many pictures remain. You should make it a practice to check this control panel whenever you start shooting. If you don't you may find you've been using the wrong settings.
BUTTONS
Buttons work in one of two ways depending on the camera. With some, you press the button one or more times to switch modes. On others you hold a button down while you turn a dial. Buttons are frequently marked with icons so you know their function.
MENUS
Menus are displayed on the monitor, usually when you press a menu button. The menu that's displayed depends on what mode the camera is in.
In shooting or record mode you usually make settings that affect the images you capture. You've seen how you can use the auto exposure mode. That's one of the most commonly used shooting modes. There are other exposure modes, and recording modes that capture movies, panoramas, and series of images.
In playback mode you can scroll through the images you have captured. You can usually display an image full-screen or display a series of smaller thumbnails. If you find images you don't want, you can delete them.
RESETTING COMMANDS
Many settings are remembered even when you turn the camera off and back on. This can really screw up photos if you don't remember to reset the camera.
When you first start taking photos, it sometimes seems that there is too much to learn all at once. Here are some things you may want to know right off.
Date and Time. The first time you use a digital camera, or if the batteries have been removed or dead for an extended period, you should enter the date and time. Having the correct date and time automatically added to each image file as you take photos will help you organize and identify your images later.
Batteries. Most digital cameras use rechargeable nickel-metal hydride or lithium batteries and come with a charger. If you can't turn on the camera, the batteries are dead or have been removed. If your batteries drain quickly, stop using the monitor to take and review pictures. If it's cold, keep the batteries or camera under your coat.
Sleep Mode If the camera seems to be turned off, it may just have entered sleep mode. If you don't use any controls for a specified time, the camera enters this mode to reduce battery drain. To wake it up, press the shutter button halfway down, or turn the camera off and back on. After an hour or so of inactivity, some cameras shut off completely. You can often change the time it takes before the camera enters sleep mode.
Indicators. When you turn the camera on, look for a battery shaped icon that indicates when the batteries are fully charged, getting low or run down empty and should be replaced immediately. Also look to see if there are any error messages and check how many pictures will still fit on the memory card.
Saving images. If an image is being stored when you turn the camera off, the image will be completely stored before the camera powers down. Don't open the battery or memory card access covers while an image is being saved. Doing so cannot only damage the image being saved; it can also damage the card.
Image review. Some cameras will briefly display the image you just took as it is being saved. Usually you can turn this review feature on or off.
Display. You can usually adjust the brightness of the monitor. Make it brighter in bright light and dimmer in dim light. It's hard to evaluate exposure, color, and focus on these small monitors, but they are a basic guide. Always confirm your results on the computer screen.
Tripods. Many cameras have a socket so you can attach it to a tripod.
TV playback Most digital cameras can be connected to a TV set so you can share your photos with others. You don't have to show the images you just took. You can copy images from the computer back to the flash card to display edited shows.
Out of Memory If you can't take a picture, it may be because the memory card is full. To free up for new pictures, move the image files to a computer and erase the memory card, delete some you don't need, or switch to a smaller image size.
Wrong settings. If your pictures are not at all the way you expect, it may be because the camera remembered a change you made in the settings and continues to use those changed settings. Some cameras remember changes even when you turn a camera off and back on.
To help you compose images, digital cameras usually have both a monitor and viewfinder. The primary roles of these two features are quite different, although there is some overlap.
MONITORS
Monitors are small LCD color displays built right into most cameras. The size is specified in inches, and the measurement, like those of TV sets, is based on the diagonal measurement. These screens range between 1.5 and 3 inches and serve a number of useful functions:
• Menus are displayed on the monitor so you can change camera settings.
• Image composition. On many, but not all cameras, you can compose the image on the screen before you take it. SLR cameras don't let you do this because they use a mirror to bounce the image formed on the lens into the viewfinder. The image sensor only creates the image when the shutter is open.
• Image review. You can review an image you've taken so you know it's the way you want it. No more surprises as so often happens when you use a film camera and pick up your traditional prints.
• Image management. You can scroll through the images taken and create slide shows, delete, rotate, rename, print, protect, copy or otherwise manage them. Many cameras also display thumbnails of a group of images so you can quickly locate the image you're looking for. Most cameras let you enlarge the image on the monitor to zoom in on details in your photo-a great way to check for details.
• Direct printing. They let you select images for printing when you bypass the computer.
On cameras that let you compose the image on the monitor the image is taken directly from the image sensor, so it is a true TTL (thru-the-lens) view. Although you can use it to compose photos as you take them, this normally doesn’t work well for a number of reasons.
• Battery drain. Large monitors drain batteries quickly, so it's best to keep them turned off and use the optical viewfinder for taking pictures.
• Glare. The image on the monitor can be difficult to read in bright sunlight.• Steadiness. You may have to hold the camera at arm's length, in awkward position that tends to introduce blur into your images through camera shake.Although the monitor should normally be turned off when taking pictures to conserve battery power, there are a few situations in which it becomes indispensable.
TIPS.
• When using a camera that isn't an SLR for close-ups, the monitor is a great way to compose and focus the image since it shows the scene exactly the way it will be in the image you'll capture.
• Odd angles. When photographing over a crowd, at ground level, or around a corner, you can compose the image without holding the camera up to your eye.
VIEWFINDERS
Viewfinders are ideal for following fast action as it unfolds -- waiting for the decisive moment. One of their advantages is that they don't draw battery power so your batteries last much longer. But that's not all. The best optical viewfinders, known as real-image viewfinders are coupled to the zoom lens and show the same area covered by the image sensor. There are two kinds of viewfinder displays, optical and electronic and they either show the scene through the lens (SLR) or through a separate viewfinder window.
Optical viewfinders on SLR cameras show the scene through the lens (TTL) just as 35mm SLRs do. A mirror bounces light coming through the lens into a prism that directs it out of the viewfinder. When you take a picture, the mirror swings up to let light hit the shutter and image sensor. These are true "what you see is what you get viewfinders because you see exactly what the lens sees. Optical viewfinders on point-and-shoot cameras show the scene through a separate window that is slightly offset from the view seen by the lens. The offset view isn't a problem except in close-up photography where parallax causes you to see a view that is slightly offset from the one the lens sees so a subject centered in the viewfinder won't be centered in the image.
Electronic or digital viewfinders use a small LCD monitor built into the viewfinder that shows you the same image being seen by the image sensor. Because these displays are electronic, menus can be superimposed over the scene so you can change settings without lowering the camera from your eye.This is especially useful on bright days when a monitor is hard to read because of glare. It's also advantageous for people who need reading glasses because the menu can be read without glasses.