Digital Photography Foundations
With most digital cameras, it's easy to begin taking photos as soon as you insert a battery and a memory card. But it's important to familiarize yourself with the different settings contained in your digital camera's menus and submenus. Human nature being what it is, of course, most of us probably take lots of pictures before delving too deeply into the instruction manual. The fully automatic mode on most cameras that handles every decision for you except where to point the camera makes this very easy to do. The Auto mode is great for those times when you need to take a picture quickly and don't want to think about which setting to use. But to achieve the photograph you're after, you'll more often need—and want—to take the camera off autopilot. Understanding the core concepts outlined in this chapter will make the difference between using your digital camera as a nifty gadget and using it as powerful creative tool.
In the first part of this chapter, we'll explain some important settings and menu options to help you know your camera better. In addition, we'll take the time to review some fundamentals of photography and how they relate to digital cameras. In the second part of this chapter, we'll look at some of the important concepts and practices that form the foundation of making good photographs.
Setting Up Your Digital Camera
The path to a camera's menu system differs from one camera to the next. With some you may be able to access it by simply pressing a Menu button on the back of the camera. With others, you might have to rotate a dial to a special position. Some cameras separate the menus into two sections: one for overall setup configuration that you access via a dial and another with specific shooting mode options that you access with a button. Depending on the camera you have, the order of the settings may vary, and some of the ones mentioned here might not be available to you, but many of them are standard on most digital cameras. We'll start with the items that are the most important for image quality.
Choosing a File Format
The first setting to consider is what file format to use when saving the images to the camera's memory card. The two choices are JPEG and RAW. Depending on the type of camera you have, RAW may not be an option. Some cameras also offer the ability to record short video clips, but for this section we'll focus on still images. We'll discuss video capabilities in Chapter 6, "Multiple Exposures and Extending the Frame."
Most consumer-level digital cameras offer only one "choice" of file format: JPEG. If this is the case with your camera, then your choice is easy. Shooting in JPEG also offers you the ability to choose different image sizes and compression levels (how small the file size is when saved to the memory card). Image size and compression are important settings that affect how many images you can fit onto a memory card, as well as image quality. We'll take a closer look at those settings shortly. As you move into the world of deluxe point-and-shoot and more advanced models, an additional format will likely be available: RAW.
As you saw in Chapter 2, "How a Digital Camera Works," a RAW file isn't really an image file format; rather, it contains the data gathered by the camera's image sensor before any post-capture processing is applied to it. A RAW file is a "recipe" to make an image. And just as you can modify or improve a recipe for a food dish, with RAW processing software you can also modify the RAW recipe and change certain aspects of how the image looks.
RAW gives you the most creative control and editing flexibility. Since the RAW format is "unprocessed," you can compensate (within reason) for exposure deficiencies in the capture during image processing. Although RAW offers unprecedented control in how you can process the captured image, for some people, RAW's primary disadvantage is that it adds additional steps to the workflow. You can't simply open the image directly into Photoshop or another program. You must convert the RAW file to a common image file format, using either the camera manufacturer's proprietary software or other products such as Adobe Lightroom, Apple Aperture, Adobe Camera Raw (which comes with Adobe Photoshop), or other programs. Many consumer-level photo sharing and editing applications, such as Apple's iPhoto, also offer the ability to view RAW files from some cameras as long as the software is up to date and offers support for your particular camera. We feel the extra conversion step is a small price to pay for the considerable creative choices and nondestructive workflow that RAW provides. If your camera supports a RAW format, and maximum quality and control over the image processing are important to you, we recommend choosing the RAW format over JPEG (see the sidebar "The Case for RAW"). For more on integrating RAW images into your imaging workflow using Lightroom, see Chapter 8, "Working in the Digital Darkroom."
RAW + JPEG
For those times when the convenience of JPEG is still important, such as when you need to hand off files to a client right after a shooting session or for the simple reason that you're not totally confidant with RAW processing yet, many cameras offer the ability to shoot in RAW + JPEG mode. This mode saves a RAW file along with a JPEG version of each shot. The downside to this approach is that it reduces the number of photos that can be saved to the memory card. But for some situations it may be the perfect compromise between the ease of use that JPEG offers and the full control and image quality available in a RAW file.
JPEG Settings: Image Size and Compression
If you are shooting JPEG, of all the menu settings you can make at the camera level, arguably the most important in determining final image quality are image size and compression. ISO and White Balance are two other important settings that can affect image quality, but they apply to both RAW and JPEG files and we'll cover them later in this chapter.
The image size in pixel dimensions is the primary determinant of how large a print you can make, and the compression level affects the quality of the image once it's written to the memory card in the JPEG format. Other settings, such as sharpening, saturation, and contrast adjustments, can also affect the quality of a JPEG image, of course, but they usually show up farther down in the menu system, so we'll cover them a bit later in this section.
Most cameras offer a number of size settings to choose from. Cameras may identify image sizes in their menu as large, medium, and small; or they may use terms like full or specify an exact pixel size, such as "10M 3648x2736" (Figure 4.1). Large or full is typically the largest image size that the camera can produce and in most cases reflects the actual size of the camera's sensor in terms of pixel resolution. Some cameras may also offer a resolution that is slightly different than the largest size to provide a different aspect ratio. If the menu choices don't list a specific pixel dimension, you'll have to resort to your camera's manual to determine the exact pixel dimensions of each setting. If you're shooting in RAW format, you do not have a choice of image size, since RAW is always recorded at the largest size the camera can produce. What you plan to do with your image, as well as how many images you want to fit onto the memory card, will determine which settings you use.
Figure 4.1 Cameras specify image size options using different terms.
The intoxicating prospect of storing hundreds of images (or thousands, depending on the capacity of the card) on a single memory card might tempt you to choose a smaller image size. The only circumstances in which we would advise this approach is if you know you'll never need to make larger prints or if you find yourself pressed for space on the storage media and have no choice at that moment. If making high-quality fine prints is your main concern, we recommend always setting the image size as large as the camera will allow (actually our recommendation for that goal would be to shoot in RAW). More pixels equal a larger file size, but more important, they also mean more detail and more flexibility if you have to make adjustments to the photo at a later time. As the saying goes, "It's better to have it and not need it than need it and not have it" (Figure 4.2).
Figure 4.2 Shooting with a larger image size (more pixel resolution; left) gives you greater flexibility and better quality if you need to crop the image later (right).
Capturing images at the highest pixel resolution offered by your camera is crucial for making fine digital prints, but we realize you won't always have printmaking in mind. If you plan on using the image only for email or to advertise an item on eBay, you might choose a smaller size. Photographs for online catalogs or other uses that have a short shelf life are also candidates for a smaller image size. Even if your image is only destined for the Web, there's a lot to be said for photographing it at a larger size. This allows you to crop or enlarge it, as well as zoom in close to do fine detail work in an image-editing program. Another reason to shoot at larger image sizes is so you can use the image for other purposes at a future time where you may need a higher resolution. Shooting at a larger size gives you more options.
Figure 4.3 Check to see if your camera provides quick access to an info summary screen so you can see all the important settings in a single screen.
When using the JPEG format, one crucial decision is how much compression to apply. The decision is always a compromise between image quality and the number of files you can fit on the memory card. Unless you need to cram as many images as possible onto the card or the final quality is not that crucial, we recommend always using the setting that delivers the highest image quality (lowest compression level). JPEG compression degrades the image, and when applied at higher compression levels, the artifacts and flaws it introduces can wreak havoc with the fine details of an image (see the sidebar "The Lowdown on JPEG Compression"). In most cases, a high-quality compression setting produces excellent image quality and generates compact file sizes that allow you to fit many images onto a memory card.
Remember that the level of compression works hand in hand with image size in terms of final image quality. Seán once had a student in a basic digital photography class who conscientiously set the compression to high quality for her first trip through Europe. When she returned from her vacation, she realized that she had forgotten to check the camera's image size settings and all of her pictures had been recorded at the smallest size. She was dismayed to discover that the quality of the enlargements was below her expectations, and she had to be satisfied with slightly soft 5-by-7 inch prints instead of the 8-by-10s she was hoping for. Cultivating an awareness of your camera's settings and checking them often will ensure that you're always capturing the image quality you need.
The ISO setting determines a digital camera's sensitivity to light. As the ISO rating doubles, the light sensitivity of the image sensor also doubles—or it can be considered twice as "fast." This is similar to how the ISO rating works for film. Unlike with film, however, where the ISO is the same for an entire roll, digital cameras let you change the setting on a shot-by-shot basis. This provides you with tremendous flexibility in your photography. You could shoot at ISO 100 in the bright sunlight for most of the day, for example, and then quickly to switch to ISO 400 or much higher if you suddenly found yourself in heavy shade or went indoors.
With film, the chemical recipe used to create the light-sensitive emulsion determined the ISO sensitivity. As you saw in Chapter 2, even though a digital camera offers different ISO settings, the image sensor has a specific sensitivity that can't be changed. To increase the effective ISO setting, the sensor's signals are amplified as they are handed off for internal processing by the analog-to-digital converter. In this respect, the ISO setting on a digital camera has more in common with the volume control on your stereo, since it just "turns up" the signal from the sensor, allowing the camera to be more sensitive in lower light levels.
Choosing an ISO setting
Most compact and point-and-shoot cameras have ISO settings that range from 100 to 1600. Many also offer an auto-ISO feature as the default setting. This setting is usually equivalent to 100 or 200 in well-lighted conditions, but it automatically rises when light levels are low. More advanced cameras offer a wider range of ISOs—up to 6400 along with an ISO expansion or "boost" feature that makes ISO ratings of 25,000 or more possible. Keep in mind that using a higher ISO setting, especially in low-light conditions, increases the likelihood that noise will appear in the image, although the noise levels on newer pro DSLRs at ultra-high ISO settings are still remarkably good. The amount of noise you will see in an image will be affected by the characteristics of the individual sensor (including the size of the sensor—expect to see more noise on images from compact cameras) and the camera's image processor (Figure 4.5). Proper exposure can also have an effect on noise levels, no matter what the ISO setting is, and noise is more likely to be visible in underexposed images. Like film grain, noise tends to rear its ugly head more often in darker areas of the image (Figure 4.6). To see how image quality is impacted by ISO on your camera, take some test shots in a dark environment at different ISO settings and evaluate them on a computer to determine your personal tolerance for image noise. If you are shooting JPEG, be sure to use the largest image size possible and view the images at 100% to see the best display of fine details.
Figure 4.5 An old radio photographed with an inexpensive compact camera (left) and a full-frame sensor DSLR (right). Both images were shot at ISO 1600, but the smaller sensor of the compact camera yields an image with more noise.
Figure 4.6 Two test shots from a Canon 5D: Though both were photographed at the same ISO (3200), the image on the right was underexposed by 2 stops, and after lightening it in Adobe Camera Raw the noise is quite apparent.
Since the ISO setting you choose will be influenced by the type of photographs you're taking and the lighting conditions you're in, there's no "right" ISO setting, but there are some general guidelines you can follow:
- Low ISO for minimal noise. If your main concern is capturing the best image quality with the least amount of noise, use low ISO settings. Every camera is different, of course, and this is where making test exposures at different ISO settings can be very valuable in helping you decide on the ideal setting for different types of images. If you find that the shutter speed at a given ISO is too slow for a handheld shot, choose a wider lens aperture or use a tripod. If you don't have a tripod, stabilize the camera by resting it on a table, the roof of your car, a tree stump or wall, or another object. When all else fails, try bumping the ISO up to a higher number.
- Higher ISO for low light or fast capture. For low-light photography or situations where you need to react fast to changing conditions or capture motion (and using a tripod is not an option), higher ISO settings will provide you with a wider range of exposure options. Most high-end and professional DSLRs produce excellent results with surprisingly low noise levels at ISO settings of 1000 to 3200. And the ISO expansion or boost feature on many cameras can produce very serviceable images even at ultra-high ISO settings of 25,000. Higher ISOs are appropriate for times when you must use a fast shutter speed that's not available with a lower ISO or if there simply isn't enough available light for handheld photography.
- Auto ISO. Many cameras offer an Auto ISO setting where the camera will adjust the ISO as the lighting levels change. Most Auto ISO features base their choice of ISO on the ability to use a shutter speed that is fast enough for handheld photography. If you'd rather not worry about keeping track of the ISO, Auto ISO may be way to go.
Photography is all about light (the Greek word photography derives from phos and graphis meaning "light writing"), but not all light is created equal. Different sources of light produce illumination with different color characteristics. A digital camera's ability to record an image with an accurate color balance is largely determined by the White Balance setting. Before we delve into the nuances of white balance and digital photography, let's take a quick look at the science behind it.
The term color temperature is used to describe the color of light, but it doesn't refer to the thermal value of the light (in other words, heat); rather, it refers to the visual appearance of the light. Color temperature is always measured in Kelvins, or K, a unit named for Lord William Thompson Kelvin, the 19th-century Scottish physicist who first developed the absolute temperature scale. In photography, the Kelvin scale describes the relative intensity of red to blue light. Lower temperatures describe light that is warmer, or redder in appearance; midrange temperatures refer to light that is white, or neutral; and the highest readings indicate light that has a cooler, or bluer, appearance (see the sidebar "Color Temperature: Don't Try This at Home"). On the warm end of the scale, you might find light created by candles or standard lightbulbs (1000K to 2500K). In the middle of the scale is typical daylight and electronic flash (5000K to 5500K). And on the cool side is open shade and overcast days (7000 to 10,000K). Table 4.1 lists different lighting conditions and their approximate color temperatures.
Table 4.1. Approximate Color Temperatures for Common Light Sources
Candlelight, firelight, oil lamps
Standard household lightbulbs
Tungsten photo lights: studio hot lights, photo floodlights
Typical daylight, electronic flash
Daylight-balanced films; electronic flash
Bright sunlight, clear skies
Slightly overcast skies
Open shade on a clear day
Heavily overcast skies
Although different sources produce light with varying color temperatures, the amazing thing about human vision is that our eyes and our brain continuously balance the colors, no matter what the lighting may be, so that we see a scene with a reasonably accurate color balance. If you leave an office building that is lit with ordinary fluorescent lights, which are closer to the green end of the spectrum, and walk out into the sunlight, you don't notice any major changes in the color balance of the objects you're viewing. Even with such a sophisticated visual system, however, there are still situations where we notice that some light sources produce illumination that's noticeably "warmer" (early morning, late afternoon, or candlelight) or "cooler" (shade or twilight).
Cameras, unfortunately, are not nearly as advanced as the human visual system, though the image sensors in digital cameras do have an edge over film. You've probably seen photos from film cameras that were taken inside under typical household lighting with no flash. An image made under those conditions usually exhibits a strong yellow color cast (Figure 4.7). The reason is that film emulsions are manufactured to produce a response that matches a general category of illumination, such as daylight. If daylight-balanced film is exposed in normal household lighting, the color balance tips toward yellow because the film is designed to produce a balanced response at 5500K, whereas the illumination indoors is a cooler color temperature (and has a warmer appearance) of about 2500K.
Figure 4.7 In an indoor shot with no flash; typical household lightbulbs create a strong yellow color cast. When the same subject is photographed outside, the color balance is more neutral.
With film, the choices for color balance were limited to daylight and tungsten lamps. If you needed to make further adjustments, you had to rely on color-correction filters. Digital cameras, on the other hand, make no assumptions about the type of light you're shooting in until the image data is processed by the camera's software. The decision the camera makes about how the colors in an image should be rendered is determined by the White Balance setting. At the most basic level, the camera uses white balance to accurately reproduce white. If you get the white balance right, all the other colors should also be accurate.
Choosing a White Balance setting
By setting the White Balance in a digital camera, you're specifying the type of light source that's illuminating the scene. There are a variety of different settings that affect the camera's interpretation of the white balance in a scene. Here is a rundown of how these settings work:
Auto White Balance. All digital cameras offer an Automatic White Balance (AWB) feature. With AWB, the camera evaluates the scene and tries to find the brightest point that is close to white. From this reading it determines the White Balance setting for the scene. Some AWB systems perform a more advanced evaluation that factors in many different areas of the scene and performs complex calculations to arrive at a white balance decision.
AWB works quite well in most situations, although this can vary depending on the image processor in the camera and the type of lighting. The main advantage of using AWB is the convenience of not having to remember to change the setting when the lighting changes. One of the advantages of shooting in RAW is that White Balance is not a "permanent" setting, and you can easily fine-tune the white balance of photographs in your RAW processing software.
As with any auto feature, however, there are times when it can be fooled, especially if the image lacks any tone that is close to white, is dominated by one particular color, or when you're photographing in low-temperature illumination, such as with tungsten lightbulbs. Even in scenes that do have obvious white areas, the presence of very bright specular highlights (a highlight that is totally white) can also throw off the AWB and prevent it from determining the correct white balance for a scene (Figure 4.8). Subtle white balance color shifts can be hard to see and evaluate on the LCD monitor on the back of the camera, particularly in bright sunlight. If you are photographing under a controlled or consistent light source, such as in a studio, it's best to use a custom white balance to fine-tune color temperature settings.
Figure 4.8 In this photo, a tungsten light source and the presence of very bright specular highlights in the background prevent the AWB feature from finding a correct white balance.
White balance presets. Most digital cameras offer a choice of white balance presets that are designed for specific lighting conditions. Standard choices include Daylight, Shade, Cloudy, Tungsten (sometimes labeled Indoors or Incandescent), Fluorescent, and Flash. Although settings such as these are useful for those times when they match the lighting you are in, we've found that the AWB feature on most cameras does an excellent job of figuring out the approximate color temperature of the lighting and adjusting the camera accordingly. The one exception to this is tungsten lighting. Even with AWB the shot is likely to turn out too yellow for most people's tastes. In this case, choosing the tungsten white balance preset gives you a more balanced shot. The main drawback to using white balance presets is that it's easy to forget to change the setting back to auto if you move to another location where the lighting is different. If you find you're shooting in tricky lighting, you can always make a few test shots with the camera set to the white balance preset that most closely matches the existing light. Fluorescent lights are likely to have the most variance from the setting your camera offers, simply because so many different types of lights fall under this general category. As with any camera setting that can affect image quality, we recommend testing the white balance presets in the appropriate lighting before you're on an actual shoot. By making test photos and then evaluating them on your computer, you'll be better able to predict how a certain preset will perform under different lighting conditions (Figure 4.9).
Figure 4.9 Besides AWB, standard color temperature presets included on digital cameras are Daylight, Shade, Cloudy, Tungsten, and Fluorescent.
Custom white balance. Some deluxe point-and-shoot cameras and nearly all DSLRs provide the capability to set a custom white balance based on the lighting at any given location. You usually do this by photographing a white object, such as a sheet of paper or a gray target, under the specific lighting conditions you want to adjust for. The goal is to shoot a normal exposure, since an underexposed or overexposed shot can give an incorrect white balance. In the camera's Custom White Balance mode, you then select this image as the source, and the camera calculates the custom white balance. The exact steps for determining a custom white balance may vary depending on your camera, and you may need to select custom white balance first and then point the camera at a target object and press the shutter button. If you don't have a sheet of white paper or a gray card handy, you can also get by using something that is a neutral tone, such as a gray sidewalk. Custom white balance is highly useful if you are in situations where the scene is illuminated by mixed light sources, such as daylight coming in through a window to blend with tungsten and fluorescent lights (Figure 4.10).
Figure 4.10 The image on the left was photographed using the camera's AWB setting. For the image on the right, a Custom White Balance setting was used based on the illumination at the location and results in a more accurate color balance.
- Setting a manual color temperature. Some higher-end cameras let you select a specific color temperature. This can be useful if you're using a color meter to determine the accurate color temperature of the lighting in a scene and want to be sure that the camera matches it exactly. At high altitudes, for example, the color temperature of the light is likely to be much higher, which produces photos with a cooler, or bluer, appearance. Although the Automatic or Custom White Balance feature may handle this condition with ease, if you're precisely measuring the color temperature using a color meter, you may find it useful to set a specific temperature. Even if you're not using a color meter, you can still make test shots and experiment with manual settings to determine which one gives you the color balance you need.
Understanding how your camera handles white balance and how to modify the settings is important because it can affect the appearance and color quality of your images. Shooting in RAW provides more flexibility for making changes to the white balance in the digital darkroom. We cover white balance as it pertains to crafting a well-exposed image in Chapter 5.
Sharpening, Saturation, and Other Enhancement Options
Since some people may find the initial image as delivered by the camera too "soft," cameras typically have a sharpening option to produce JPEG images that look sharper and more finished. Fortunately, many cameras allow you to choose the level of sharpening applied, or even to turn it off completely. Our view on the sharpening feature is unanimous: If your camera provides you with a way to disable it, turn it off for good.
The reason for our impassioned view is that sharpening is a destructive process that permanently alters the color and contrast of edge pixels—areas of the image where light and dark colors are adjacent to each other. The camera just sees a bunch of pixels and applies a sharpening amount based on canned formulas that are hard-wired into it. A camera doesn't know what your photograph requires or how you might want to use sharpening, so the sharpening it applies may not be appropriate for the image. This is especially true if you plan to make prints, since the amount of sharpening that you apply is influenced by the subject matter and the size of the final print.
We have the same philosophy when faced with options to alter contrast, brightness, and color saturation: Turn these features off! All of these decisions and enhancements are best applied later in an image-editing program, where you can apply them in a way that complements the specific image and in a flexible manner that doesn't harm the original (Figure 4.11).
Figure 4.11 The image on the left is a detail view showing a photo with no in-camera sharpening applied. The image on the right is the same subject with in-camera sharpening turned on. Although the sharper image may initially look better, it offers less flexibility in terms of image editing and printing.
Color Space Settings
Digital cameras, monitors, scanners, and televisions all create color using the RGB color model, which is based on red, green, and blue, the three additive primary colors of light. Within the range, or gamut, of RGB colors there can be different subsets of colors, known as color spaces, that describe different gamuts within the overall RGB color model. A simplified way to think of this is to imagine a large container that holds all the colors you can see. Within this container are several smaller containers, or color spaces, with each one describing a slightly different range of colors. Some of the containers might have more greens and cyans in them, for instance, whereas others have more oranges and reds. Some containers may also have more intense, or saturated, colors than others. Color spaces with a larger gamut can contain more colors than smaller-gamut color spaces.
Most entry-level, point-and-shoot digital cameras do not offer a choice of color space settings. They create color based on an industry standard color space known as sRGB. Microsoft and Hewlett-Packard developed sRGB, basing it on the color gamut of the average, inexpensive monitor (aka the lowest common denominator). Many deluxe point-and-shoot cameras and higher-end DSLRs offer a choice between sRGB and Adobe RGB for the JPEG files they create. The difference between these two color spaces is primarily gamut size; Adobe RGB has a much larger gamut than sRGB (Figure 4.12).
Figure 4.12 These two views from the 3D gamutgraphing feature of the program ColorThink (chromix.com) compare the gamuts of sRGB—shown as a solid color shape—with Adobe RGB (1998), shown as a wireframe.
If your camera offers you a choice, the best choice depends on what you ultimately need to do with the image. If you're only concerned with emailing photos to friends and family, creating images for the Web, or making prints for scrapbooks or photo albums, there's nothing wrong with choosing sRGB. However, if your work consists of creating professional, exhibition-quality prints or if you're shooting images destined for reproduction on a printing press, Adobe RGB is the better choice. In reality, all color spaces involve compromise and there is no single ideal color space. But if you have to decide between the two, we recommend Adobe RGB. Camera color space settings only apply to JPEG images. Because RAW files are unprocessed, these settings do not affect them. Color space for a RAW file is assigned in the RAW conversion software.
Additional Camera Settings
Besides the basic settings we've already discussed, you should be aware of a few others:
- LCD brightness. Many cameras feature an LCD brightness control that allows you to increase or decrease the brightness level of the LCD screen. If you are in bright sunlight trying to review your images, bumping up the brightness of the LCD may help you to see the display better, although this can also throw off your perception of the actual tonal values in the scene. It's better to keep the LCD brightness at a set level and use other methods to get a better view of the LCD screen, such as using an LCD viewing hood or the jacket off your back to create shade.
- LCD/system sleep. This determines the length of inactivity (in other words, not pressing any buttons) required before your camera enters a sleep or standby mode. If you want to conserve your battery, choose a relatively short amount of time such as 15 to 30 seconds; if you want the camera to be always at the ready, set a longer interval. If your camera has a separate setting for LCD standby, choose the shortest time available. If you don't use the LCD for framing the image but rather rely on the optical viewfinder, see if you can turn off the display for all but reviewing purposes. The less the LCD is on, the longer your batteries will last.
- Setting the date and time. This is pretty straightforward, but it's definitely something you want to do before you take any photos. Digital cameras record the date and time of day you created an image, as well as other information, and include it with the image file (see the section "Metadata" later in this chapter). Computers can also use dates to sort images, so having an accurate date and time attached to your images is important. Although having the accurate time may seem like a trivial detail, it can be very useful to know the time of day a photograph was taken. For world travelers, see the sidebar "Managing Capture Times Across Different Time Zones."
File-numbering options. Digital cameras name files using a combination of letters and sequential serial numbers (such as DSC_2051.NEF or IMG_0406.CR2). Although this filenaming scheme is hardly useful if you have to sort through countless folders of digital photos, it does provide a starting point. On many cameras you can specify how you want to handle the numbering sequence.
Continuous Numbering continues the number sequence even after you've changed storage media. This setting ensures that all your shots will have discrete numbers, preventing you from accidentally overwriting an earlier image with the same file number. Cameras usually assign an upper limit to the numbering scheme, such as 9999, beyond which they'll start over again at 0001.
Auto Reset, or Auto Renumber, automatically resets the file number to 0001 whenever you replace the storage media card. The main drawback to this system is that if you are not careful with how you organize your files, newer files could accidentally overwrite earlier images with the same name. If you store your images from each session in separate folders, there is less of a chance of conflicting filenames, but the possibility does exist.
We all use Continuous Numbering and batch rename the camera files when downloading or importing them into an image-management application, such as Lightroom. We'll cover using Lightroom to batch rename files in greater detail in Chapter 8.
Formatting the Memory Card
When you first use a memory card, you should format it using the camera's formatting option to prepare the card for use with that camera. Although some cameras let you shoot with an unformatted card, certain camera-specific features may not function properly until the camera has formatted the card. You should also reformat each time you need to erase a card—for instance, when you want to reuse it and take new photos. Formatting a card erases the directory structure on the card. The images are not removed from the memory card until new images replace them, but with no directory structure referencing the files, you can no longer view them. Since this action is irreversible (there's no Undo command), be sure you're not wiping out important images that have not been backed up yet. See the sidebar "Recovering Deleted Files from a Memory Card" in case you inadvertently reformat a card with important images.
When you hook up the card to your computer to download photos, either via a card reader (highly recommended) or directly from the camera, you may be tempted to delete the files you've already transferred by dragging the folders on the card to the computer's trash can or recycle bin. We caution against this and recommend formatting the card in the camera to delete the files. Although there may be no harm in deleting images on the card from your computer, it's best to format the card in your camera. Since the primary purpose of the card is to be the place where the camera saves its image files, it makes sense to let the camera do it so that the card is optimized for use in that device. If you have more than one type of digital camera, we recommend having dedicated media cards for each one. Not all cameras can read cards formatted in other cameras, so rather than risk losing images, we dedicate media cards to each camera to avoid the card formatting issue.
We also suggest that you reformat the card after every use instead of simply deleting the files using the camera's erase command, because the File Allocation Table (FAT) is regenerated with each new format. As with any computer file system, data corruption can slowly build up over time; formatting the camera media card after confirming that you have safely downloaded and backed up the images before each use ensures that you'll start with a clean slate.
To ensure that the photos you have downloaded are fine and do not suffer from any file corruption issues (rare, but it does happen from time to time), import the images into your digital editing or file management program (e.g., Lightroom, Adobe Bridge, Aperture, BreezeBrowser, etc.) before you reformat the memory card. If the program can generate thumbnails and large previews, the files should be fine. You should also make a backup copy of the images on a separate hard drive before the card is reformatted. Hard drives do crash, so having duplicate copies of important images on a different drive is one way to guard against such hardware failures.