About Digital Still Cameras
A Bit About Digital Cameras
Digital cameras work very much like film cameras. The quality of the image depends on the quality of the lens and the sensor chips in the camera (which convert the light into a digital signal).
The more manual control enhancements the camera has, the higher the price tag. The least expensive models have fixed settings for all controls (shutter speed, aperture, focus, etc.).
Some models have a built-in zoom lens, which is limited to an optical zoom factor of about 3 times (approx. 38 mm to 114 mm). But some can go as high as 10 times (approx. 38 mm to 380 mm). Zoom amounts can be enhanced with digital zoom technology.
Some higher-end models are just camera back and accept interchangeable lenses. Others have the capability to use screw mount lenses used on video cameras. These options allow for close-up portraits and wide-angle shots. Close-up lenses are also available for some models.
Most cameras come with a built-in flash. The higher-end models have a hot shoe for an attachable flash unit, allowing for better lighting options. Some models have adjustable f-stops (aperture settings). The lower the f-stop setting, the better your image will be in low-light settings. Shutter speeds are also a consideration. Moving images require a faster shutter speed. 1/60 of a second is the lowest shutter speed for hand-held, stop-motion photography.
Many of the higher-end models allow you to shoot short movies. The duration of these movies are dependent upon your memory card size. The quality of these movies varies greatly from camera to camera. If this is an important feature to you, be sure to test the camera in the store before you decide which to purchase.
Digital cameras vary in how many images they shoot, and how they store them. How you will (in the studio or in the field) and what you will be shooting (still lives or race horses), will be a major factor when deciding what type of camera you purchase.
Consumer and mid-range digital cameras can now store up to 100s of images at a time. There are a number of different types of storage options, memory cards, sticks, and CDs. Memory options are available in many different sizes, the larger the storage device the more images it can hold. Many cameras now come with both memory card and stick slots available.
The cards range from 2MB to 128MB+ storage capacity. How many shots you can store depends on the resolution and compression quality of the image and the size of the card. These cards are reusable but can be a bit expensive. If you will be in the field shooting, larger cards or a camera that saves to an external disk may be the option for you.
All Best and Standard are not the Same!
Be aware that most cameras have two or more image quality settings (or may use interchangeable memory cards for extra storage space). Images can be set to standard, high quality, and beyond. Standard can range from 320x240 pixels to 640x480 pixels. High quality images can run from 480x240 pixels to 1,024x768 pixels or more. Check each camera manual to see what the manufacturer describes as its camera’s “standard” and “best” resolution. Compare these details before you buy a camera.
Optical Viewfinders, Electronic Viewfinders (EVF), and LCD Displays
Many of the consumer level point-and-shoot cameras use optical viewfinders on their cameras. This means that they have a separate viewfinder that works with the lens but is independent. What this means to you is that what you see in the viewfinder is not what you get in your image. This situation is especially true when you zoom in on an area. Many manufacturers include little bracket lines in the viewfinder to help compose the image. This is why many people who use optical viewfinder often use their LCD screen to compose their shots. Some camera makers have discontinued viewfinders altogether and have bigger LCD screens.
Most cameras have an LCD screen attached to the camera body, which allows you to compose and view your shot instantly. This feature allows you to preview your shots and helps you decide whether to keep it or erase it and shoot it again, without downloading it to your computer first. Some LCDs can swivel, which improves your chances of good shots in tight situations. The problem with LCDs is that you may not get an accurate rendering of the image: the image may look bad on the LCD, but it could be salvageable after it is downloaded. You may find the LCD hard to view in bright sunlight, and LCDs vary in size and brightness. If you will be using the LCD for setting up your shots, look for big bright LCDs. While in the store, look at the LCD in bright sunlight if possible.
Many cameras come with EVF, which acts like a traditional camera viewfinder. It allows you to bypass the LCD screen and see what the camera sees along with the camera settings. Often, when you snap the shutter, a small version of the image will appear in the viewfinder. You also have the added benefit of viewing menu options in it, bypassing the need to use the LCD screen. Both the EVF and LCD use battery power to display the preview image.
Sometimes these EVFs have trouble viewing the shot in dimly lit situations, a night shot, etc. Some models come with illuminated EVFs to try to alleviate this problem.
How They Work
Single shot cameras use a technique called "striped area array." Basically, RGB filters work with a sensor in the camera called a CCD (charge-coupled device). Each element in the array captures red, green, or blue information for a single pixel. The software included with the camera interpolates the color information for the other channels from neighboring pixels to create a whole image.
Image quality varies from camera to camera, depending upon the size and quality of the CCD, the filter placements, and the interpolation software. The lower the image resolution the higher the likelihood of color fringing on the edges of objects in your image and artifacts appearing in the shadows.
Chromatic aberrations, most often known by its more descriptive name “purple fringing”, can appear on images where high contrast areas meet dark and sometimes mid-tone areas (i.e., a bright sky meets dark mountains, or the side of a brightly lit building meets one in shadow, thin tree branches against sky).
In general, if you're reducing these images before printing, some or most of the purple fringe will not be noticeable. If on the other hand, you are enlarging the image, the dreaded purple fringe can become very noticeable.
Some cameras handle this problem better than others. The problem is not just with inexpensive models--even the best SLRs (single lens reflex) can suffer from purple fringing.
Types of Cameras
Basically, 4 types of digital cameras are available to choose from today. Web cams, point-and-shoot, midrange, and digital SLRs. Like traditional photography, it is important to buy a camera that meets your needs and skill level. Do not spend extra money on features you don’t need or will never use.
Web cams and cell phones take very small images that are only suitable for web pages.
Point-and-Shoot cameras are available in a wide range of resolutions but are noted for their ease of use. They are usually fully automatic. They often have a range of scene presets to choose from, with few or no manual controls. These cameras are best suited for those who wish to take images with out fussing with controls. If you are considering a point-and-shoot camera, if it is optical, be sure it has a large and bright viewfinder and LCD display.
Midrange cameras come in a wide range of resolutions and offer more features, including scene presets and auto and manual override settings. Some also offer a few more film ASA (American Standards Association) speed options. They usually offer a larger range of image sizes, formats, and compression options than the point-and-shoot models. In most cases, these cameras have accessories that can extend or enhance their performance such as telephoto and macro lens extension kits, the ability to accept an optional flash unit, professional filters, etc. These cameras are for those who are comfortable with photography and who want to have the freedom to override the auto settings. They’re also for those who want to advance their photography skills or move up from point-and-shoot.
Digital SLR cameras are most like traditional professional cameras and feature through-the-lens viewing. What you see in the window is what appears on the picture. They are usually digital camera bodies, and the lens comes separately. The good news is they usually come with one general-purpose lens. They are available in only higher resolutions, offer scene presets, auto settings and lots of manual overrides, and more film ASA options. They also have many options for saving and compressing images. Most often, they have an internal hard drive to store images or the option to attach one. These cameras are not for the point-and-shoot user, and they may be more than the average midrange camera user needs. This camera is aimed at the professional photographer who is making the move to digital or the midrange user who is (or has become) more serious about digital photography.
ResolutionHow Many Pixels Do You Really Need?
Digital cameras measure their digital image output in megapixels, which is the total number of pixels in the image. How the pixels are arranged will determine the final size and quality of your final printed image.
For example, I took a picture with my 2.1 megapixel camera. I opened the image in Photoshop and saw that it was 1600 pixels wide and 1200 pixels high. The print dimensions were 22.222 inches wide and 16.667 inches high with a resolution of 72 pixels per inch. My printer works best with print resolutions of 260 or 280 pixels per inch. So, I need to rearrange the pixels to get the best output.
When I change the image resolution in Photoshop to 280 pixels per inch in the resolution control box, the image height and width change to 5.717 inches by 4.286 inches. The total number of pixels stays the same but are now reorganized based on the desired output.
With the 2.1 megapixel camera, I am limited to the optimal output size of approximately 5x7 inches. I could print the image at its original large 22 x 16 inch, 72 dpi state, but the quality of the print would not be very good. Noticeable pixilation would start to appear.
When are More Pixels Important?
Your printer’s resolution and the size images you want to print are important factors to keep in mind when deciding on pixels. The more pixels you have to work with, the larger and crisper the images you can create. When larger output is your most important consideration, in most cases, the more pixels you can afford the better. If you don’t print larger format prints, or if you only use your images for online distribution, a less expensive model with fewer pixels may make better sense for you.
More pixels also come in handy if you crop your images using computer software. With a larger number of pixels, you can crop out some of the image and still have enough pixels for a large printout. You may not be able to get a full size print of the original image before your edit, but depending on the amount of your crop, you could get pretty close.
Zoom Factors Optical and Digital
When reading the manufacturer’s information about their cameras, you will often see “optical” and “digital zoom” listed in the features. Often the optical zoom will be a lower number and than the digital zoom.
The difference between optical and digital is really very simple: It’s just what it says it is. Optical zoom is the base level of zoom that the lens can zoom in and out. With digital zoom, the camera tries to increase zoom range by cropping the image previewed in the viewfinder. Once cropped, it blows that area up as if you zoomed in closer. It is a bit like interpolation on scanners. While the extra zoom possibilities seem great, the images employing this feature usually come out soft (blurry) and can become very grainy.
If a large zoom range is important to you, when faced with a zoom choice, always choose the camera with the higher optical feature over the digital zoom feature.
Digital cameras devour batteries. Some companies package recharger kits with the cameras, others offer them as an extra purchase. In the long run, you would do well to invest in the recharger kit and purchase three sets of rechargeable batteries. This set up allows you to have a set in the charger, a set in the camera, and a replacement set charged and ready to go.
Sometimes the camera manufacturer uses its own specialized batteries, which only work in that particular camera. It would be a good idea to get yourself at least one backup.
Always use the factory recommend battery type in your camera. Some cameras can accept any type of batteries, others have more specific requirements. Using the wrong type of batteries in your camera can harm it. If you see any corrosion appear on the tops of your batteries, discard them. Leaking batteries will damage your camera.
You can save your battery life by taking photos and selecting the camera’s options setting using menu options through the viewfinder, not the LCD monitor. Another good habit to get into is not to rely on battery power to download your images to your computer. Use your power adapter when downloading images to your computer whenever possible, or better yet, use a card reader.
Connections and Formats
Most cameras come with software and connections for both Macintosh and Intel-based computers. Most cameras save in JPEG or TIFF format, or its downloading software will convert the image to your favorite format.
Image Compression How Images are Stored
Digital cameras save files in either an uncompressed or compressed format. How the image is compressed (or not compressed), is generally set by the user. Most digital images are very large, without compression very few images would fit on the average memory card.
Generally the options are TIFF for uncompressed files and various degrees of JPG compression. These settings are referred to as normal, fine, superfine, and good, better, or best. The more compression applied, the smaller the file size; therefore, more photos can be stored on a card. With high compression, digital artifacts and lost details can occur. When less compression is applied, fewer images can be stored on the card, but there are fewer JPG artifacts in the image.
Most manufacturers use a middle of the road setting of “better” or “fine.” Unfortunately these terms are not standardized. What is better on one camera may be good or best on another. Be sure to research these differences before buying a camera.
Here’s a chart illustrating compression sizes.
Memory Card (Digital Film) and Card Readers
Many of the newer model cameras are able to use two or more types of memory cards. This is a very nice feature that some camera companies are using as an enticement to switch camera makers. This set up enables you to use your older style memory cards preferred by the other camera maker (and that you have lots of money invested into), in your new camera. Some of the higher-end cameras come with a small hard drive or can accommodate one. Some cameras also burn files directly to CD storage.
To make downloading easier, you can purchase a handy device to read your memory cards. You insert your memory card into the device and it is reads the files like an external hard drive. Some of these devices come with the ability to accept multiple types of cards. These units are very handy when you have more than one camera type in a household or office environment.
Older models of card readers came in the shape of floppy disk. You inserted your memory disks into the reader. The reader then was inserted into the computer’s floppy drive and appeared on the desktop just like a disk.
A number of printers on the market are made specifically for digital camera output. Some come with card readers built in. The best for photo quality images at this point in time are inkjet and dye sub technologies. Sometimes the camera manufacturer will recommend an appropriate printer for the camera.
There are printers with inks sets ranging from 4 to 8 color ink cartridges. Some of the colors are packaged in one cartridge and others come packaged individually. Six or more color inks will give you optimal color reproduction. Additionally, the higher the resolution of the printer, the more photo-real the printed image can appear. Of course if your image is a large image, with a 72-pixel resolution, then higher printer resolution will probably be wasted, and the image will appear dotty and pixilated.
Some companies have made archival inks available which are waterproof, and according to the manufacturers, can last as long as 100 years on the right paper and under the right lighting conditions. These inks usually need to be used with higher-end papers, which are sometimes referred to as professional papers. If used with lesser quality papers, they may not be waterproof, or light safe, and the colors may be inferior and contain colorcasts.
Dye sub printers are very different from inkjet printers. The ink is joined to the paper in a sublimation process, and become one. This technique usually an expensive option, as you have to use a paper that the special inks can be sublimated to. The paper and inks are not easily available in stores. But, the output can be very good when the image resolution is matched to the printer.
Always remember that in most cases the printer will NOT be able to accurately reproduce on paper the colors on your screen. Monitors and inks have an altogether different range of colors, known as color gamut. Please study this very important issue before you spend lots of time, ink, paper and money, only to end up frustrated with your image output. That said, many of the newer model printers are doing a great job fixing gamut problems with their software. It is important to read the manual to set up the printer for the best possible output. Always take notes about your settings if you change them. If you’re happy with the image, and you want to reproduce it a month or two later, you’ll know what settings you used.
Keep in mind that if you are just buying a photo printer exclusively for your digital images, and will not be printing 8x10 or larger images, or if your camera can’t create acceptable output at those sizes, you don’t need to buy an 8x10 or larger format printer.
The great news about photo printers is that they are getting cheaper every day. The replacement inks and paper supplies are another matter altogether.
See the "About Color Printers" page to get more information about color photo printers.
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