Table of Contents
| Ch. 1 | Before You Shoot | 1 |
| Ch. 2 | Shooting Great Portraits | 20 |
| Ch. 3 | Photographing Children, Pets, and Social Events | 44 |
| Ch. 4 | Shooting Interiors and Exteriors | 130 |
| Ch. 5 | Shooting Beautiful Landscapes | 156 |
| Ch. 6 | Shooting Panoramas and Virtual Reality | 176 |
| Ch. 7 | Shooting Your Stuff | 196 |
| Ch. 8 | Shooting Past the Boundaries | 220 |
| Ch. 9 | Organizing and Sharing Digital Photos | 238 |
| App | An In Depth Look at Digital Technologies and Procedures | 254 |
| Index | 271 |
| About the Author | 288 |
Read a Sample Chapter
Shooting Digital
By Mikkel Aaland John Wiley & Sons
ISBN: 0-7821-4104-8
Chapter One
Before You Shoot
Chapter Contents
Bridging the Film/Digital Gap The Right Digital Camera Knowing Your Digital Camera Software Solutions Accessories That Make a Difference Finding Up-To-Date Information and Support
You'll increase the odds of making great digital photos if you take a few moments to ground yourself in some basics. It's useful, for example, to understand why shooting digital is inherently different from shooting film. And even if you already own a digital camera, you should know whether the camera you are using-or the one you are thinking about upgrading to-is really the right digital camera for your needs. This chapter will get you started on the road to making great photos with your digital camera.
Bridging the Film/Digital Gap
Since most of us come to the digital world from the world of film, it's comforting that much of the nomenclature of digital photography is familiar. Digital cameras have lenses, f-stops, and shutters just like traditional cameras. Light is captured and recorded. Images are stored and shared. Many film photographers entering the digital camera world will quickly get up to speed because of the many similarities between digital and film photography. However, it is important to know that the differences are also great, and if you apply your old knowledge indiscriminately to the digital world, you are likely to get unsatisfactory results or not fully utilize the capabilities of the new medium. Let's look at some of the similarities and differences.
Capturing Light: Electronic vs. Chemical
Both digital cameras and film cameras capture and record light. However, film cameras rely on a chemical process. Silver halide crystals change when struck by light, forming a latent image that is revealed upon development with a chemical agent. Figure 1.1 summarizes this familiar process.
Digital cameras rely on a much more complex system that includes several interconnected electronic components and sophisticated image processing. Let's look at this system in more detail.
The Digital Capture and Storage Process
Digital capture starts with the sensor chip. This chip contains an array of photoreceptors, each capturing one pixel of the ultimate image. The number of receptors in the chip is what determines the camera's maximum resolution. In most systems, a layer of filters is applied over these receptors (see Figure 1.2), so that each one can capture only one of the primary colors-red, green, or blue. These colors are the basis of the RGB color model used in all computer imaging. Electronic processing, either in the camera or in a computer, then combines these separate R, G, and B values into RGB pixels in the image.
The processing of the digital data from the sensor is the most complex part of the process, and also the most variable. Unless you've chosen to save the image in the RAW file format, the camera's onboard processor will organize the separate R, G, and B pixel values into RGB data and a perform variety of other steps before assembling the final image. This processing may include compression (in the JPG file format) or no compression (in the TIF file format). You'll learn more about these formats in Chapter 8's "Know Your Camera: File Formats" sidebar, and in the Zooming In appendix under "RAW Data Revealed."
After light is captured by the sensors and the processing is complete, the information (data) is passed on in digital form to some sort of built-in memory system or, more commonly, to an external storage medium such as the commonly used SmartMedia or CompactFlash card.
The sensor and electronic system that carry out the task of digital processing and storage are built entirely into the camera and cannot be easily swapped and upgraded. By comparison, film has individual characteristics dependent on brand and manufacturer, and those characteristics are independent of the camera itself. You can easily switch from a fine-grained film to a fast, grainy one by simply replacing one roll with another in the camera.
Comparing Resolution
Film resolution, expressed as resolving power, is a function of the size and structure of the silver halide particles (Fine, Medium, or Coarse), the emulsion thickness, and the actual size of the film (35mm, 120mm, etc.). Digital camera resolution is based on the number of pixels contained in a particular sensor. The number of pixels is expressed either as an "A ???" form with "A" representing the number of pixels in the width and "B" the number of pixels in the height of a sensor (for example, 2560 ??1920 pixels) or as a total number of pixels (for example, 4,915,200 pixels, or more simply, 4.9 megapixels).
In general, the more pixels a sensor is capable of capturing, the finer will be the detail that is recorded. I must qualify this statement though, because there are some sensors on the market-notably ones created by Foveon and Fuji-that squeeze more color data from each pixel, thereby making a side-by-side, pixel-to-pixel comparison between sensors less meaningful. (Read more about this in Zooming In under "Sensors Expanded.") Sometimes the documented number of pixels may include pixels that aren't even actively used, introducing yet another variable.
Some of the earliest digital cameras captured only 640 x 480 pixels (.3 megapixels)-just enough pixels to fill a small computer monitor, and barely enough to produce a decent 3" x 4" print. Nowadays a typical 3-megapixel consumer digital camera captures around 2048 x 1536 pixels, which is plenty enough resolution to produce a decent 8" x 10" print. Table 1.1 shows what size prints you can reasonably expect to produce from various resolutions. Note that these are general guidelines and actual results will vary depending on the type of digital camera and output device used and other qualities of an image such as sharpness, color, and content.
Note: Roughly speaking, it requires a digital camera capable of capturing approximately 6 megapixels to match the resolving power of a medium-grain 35mm film. Other digital camera variables such as lens quality, sensor characteristics, and image-processing capabilities make a difference as well.
Considering Exposure Latitude
Many sensors don't have the exposure latitude between light and dark that film provides, and sensors aren't capable of producing good results in low-light situations as successfully as some films can. Professionals, of course, have found ways around these limitations and I'll pass on their knowledge in the appropriate sections. Of course it is also important to keep in mind that this is a temporary situation. While we've approached the limits of what film can do, the capabilities of electronic capture will likely surpass those of film.
Bottom line: Unlike film cameras, digital cameras depend on a complex array of electronic components, all of which contribute to image quality-or lack thereof.
Lenses: Getting the Numbers Right
Digital cameras, just like a film cameras, rely on lenses to collect and focus light onto the sensors. If you've used a 35mm film camera, you are probably familiar with how lenses are numerically differentiated in terms of focal length. (Focal length is the distance between the optical center of a lens and the medium that captures the image-either the film or sensor surface.). For example, a lens with a focal length between 40mm and 55mm is considered "normal" and covers a field of view similar to human vision, about 50 degrees. Focal lengths less than 40mm are considered wide angle and focal lengths over 55mm are considered telephoto, with a narrower field of view. A lens designated as wide angle will expand the field of view, and long telephoto lenses narrow the field of view and appear to bring far objects close. Zoom lenses provide a range of fields of view, often going from wide angle to telephoto. A versatile zoom lens might provide a range of focal lengths, say from 28mm to 200mm. And so on.
Note: Because the sensor of a digital camera is physically different and responds to light differently than film, digital camera lenses are often designed from the ground-up to take into account these differences. Some camera manufacturers are more successful than others in producing lens/sensor combinations that contribute to overall image quality. If you use a digital camera that accepts interchangeable lenses, it is important that you choose lenses carefully. Not all lenses will give you optimal quality. A lens that works fine with a film camera can produce color aberrations, flare, and lack of sharpness when used with a digital camera.
When shopping for a digital camera it's natural to want to compare focal lengths of digital camera lenses with those of familiar 35mm film cameras. But although a digital camera's "normal" lens will capture approximately the same field of view as a film camera's "normal" lens, the physical focal length considered normal is usually much shorter. (Because of this difference, it's typical to refer to "35mm equivalent" focal length when discussing lenses for digital cameras, and I'll use that term throughout this book.) A 50mm lens that is considered "normal" for a 35mm film camera would be considered a telephoto lens for many digital cameras.
Why? Because most digital cameras use sensors that are smaller than 35mm film-sometimes only a quarter of the size-and the smaller the sensor, the shorter the normal focal length. Figure 1.3 illustrates this point. With the same physical focal length, a 35mm film camera (which has a 24mm x 36mm frame size) would show a somewhat larger field of view, with less magnification, than a digital camera with a relatively large sensor (such as the Nikon D100, with a 23.7 x 15.6mm sensor). With the 5.27 x 4mm sensor on the Minolta DiMAGE X, we have a much smaller field of view and more magnification.
Different digital cameras use different size sensors, so focal-length equivalents will vary. For example, 30 mm is considered a normal focal length for the Nikon D100 while 7 mm is considered normal for the DiMAGE X. For now, most camera manufacturers provide 35mm focal-length equivalents when necessary, either on the lens housing or in the manual. If you can't find the 35mm focal-length equivalent for your particular camera, you can refer to the owner's manual or to the manufacturer's website. With some digital camera specifications you will see a number referred to as a 35mm "multiplier factor." Multiply this number by the focal length of your lens to get a 35mm film equivalent. For example, if the multiplier is 1.5 and you are using a 100mm focal length, 1.5 x 100mm =150mm, which is the 35mm equivalency.
Note: Because digital camera manufacturers calculate 35mm equivalents using different criteria, allow for up to a 15% variation when comparing one digital camera's equivalent focal length with another's.
If all else fails, there is a relatively straightforward relationship between the diagonal dimension of a sensor (or film) and what is considered a normal focal length. If, for example, the diagonal measurement of a sensor is 12mm (as it is for the sensor used in the Nikon Coolpix 990), then the normal focal length is 12mm. (The Nikon actually comes with an 8mm-24mm zoom lens, which translates to 38mm-115mm in 35mm film equivalence). The diagonal measurement for the sensor in the 14-megapixel Kodak Professional DCS Pro 14n digital camera-and the Canon EOS-1D-is the same as 35mm film-about 43mm-which explains why a 50mm "normal" lens on the Kodak and Canon cameras will provide the same field of view on a 35mm film camera. (Many people have been taught that a 50mm lens is a normal lens for a 35mm camera, but as you can see by the math, 50mm doesn't fully represent the normal human field of view. Many pros consider a 35mm lens "normal" for a 35mm film camera.) Some manufacturers list the diagonal measure of a sensor with the camera's specifications.
Note: Lens zoom capabilities are sometimes expressed in multiplication style, such as 3x or 6x. This refers to zoom range, starting at the widest angle. A 40mm, 4x lens, therefore, has a range of 40mm-160mm. A 35mm, 10x lens has a very large range, from 35mm-350mm. Digital zoom is something altogether different. It has nothing to do with the lens itself, but refers to software interpolation that occurs after an image has been captured.
Knowing what you do now, you'll better understand why it's rare to find a digital camera equipped with a lens that has less than a 30mm focal length equivalent. Only the more expensive digital cameras with larger sensors give you the option of wider lenses. Even then, if you place a 12mm fisheye lens on, say, a Nikon D 100, it will still be equivalent to only about 20mm on a 35mm camera-which is wide, but not super wide. (Accessory, add-on lenses can extend the wide-angle capabilities of many digital cameras to a degree; however, there is some tradeoff in quality.)
Bottom line: Focal length equivalents will vary between different digital cameras with differently sized sensors. Don't expect a 1:1 relationship between the angle of view of a lens used on a digital camera and the lens used on a 35mm film camera. Finally, the smaller the sensor, the less chance your camera will provide an effective wide-angle view.
Aperture and Depth of Field
It's not only focal length numbers that are different in the digital and film worlds. Aperture comparisons between a digital camera and a 35mm film camera-at least when it comes to the depth of field-won't always give you the same results either.
Apertures, which are found in most lenses, work in tandem with shutters to control the amount of light that passes through to the sensor or film. Aperture size is expressed as f-stops, with "f" representing the focal length of a lens. f/2, therefore represents an aperture diameter that is 1/2 the focal length of the lens, and f/16 is an aperture diameter that is 1/16 of the focal length of the lens. f/2 is wider than f/16 and allows more light to pass through the lens. Theoretically, an f/5.6 setting on any lens, on any camera-digital or film-will always let in the same amount of light.
Depth of field is the range of acceptable sharpness in front of and behind the plane of focus. As you'll see throughout the book, the ability to control depth of field-either to isolate a subject from its background, or to put more objects in focus-is an important creative technique.
As most of you probably already know, wider f-stops yield a limited depth of field, while narrower f-stops increase the depth of field.
But depth of field is not determined only by f-stop. It's also determined by the focal length of a lens (longer lenses produce less depth of field); the distance from the lens to the object (the closer the lens is to the subject the less depth of field); and, just as importantly for the purpose of this discussion, by the size of the sensor-or for that matter, the film. (For a very technical discussion of this topic I invite you to visit my website: shooting-digital.com.)
From a purely practical point of view, the smaller the sensor your digital camera uses, the more depth of field is produced for any given lens, f-stop, or distance. Depth of field, therefore, varies from one digital camera model to another-and rarely will you get what you might expect without some experimentation.
Later in the book, I'll give you a way to test your digital camera and lens for depth of field, and I'll show you ways to deal with more depth of field than you want (?? "Know Your Camera: Controlling Depth of Field" in Chapter 2). For now, just know that this is a potential issue with huge implications, especially, for example, if you are shooting a portrait and you want the background to go more out of focus and it doesn't.
Bottom line: The amount of depth of field produced by your digital camera might not be what you expect. You'll need to experiment.
Shutters: Another Way to Control Light
Digital cameras need shutters to control light just like film cameras. Some digital cameras use a shutter that is mechanical, not unlike the shutters used in a film camera. The shutter-be it a leaf shutter or a focal plane shutter-controls the amount of light that strikes the sensor. The faster the shutter, the less light is allowed past; the slower the shutter, the more light. Remember from basic photography that varying the shutter speed and changing the f-stop is how you get more control over the amount of light hitting the film or sensor, and also how you can stop or blur action or control depth of field.
Some digital cameras use the sensor itself as a shutter. This requires a special sensor but essentially the pixels themselves are told electronically when to turn on and when to turn off. As you can imagine, using this electronic method can produce much faster speeds than anything mechanical. Engineers for Olympus, for example, have produced speeds of 1/18,000th of a second. Speeds like this are inherently impractical because they require so much light (and such a wide aperture). Using sensors as high-speed shutters in this way has its tradeoff: it lowers the effective resolution of the sensor.
(Continues...)
Excerpted from Shooting Digital by Mikkel Aaland Excerpted by permission.
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