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A few digital SLR cameras include an option to record images in TIFF format. A TIFF image is comparable in quality to a RAW image, but is substantially larger. I can see only one benefit to using this capture mode: you don’t need to convert the image using special software. The drawbacks outweigh this benefit, however. Because each file size is so large, your memory card will hold fewer images. In TIFF capture, you cannot shoot more than one image in a sequence. Also, image processing time is extremely long, which can be very frustrating.
Recommendation: The “Best” Capture ModeSome photographers, particularly those specializing in landscapes, prefer to use TIFF capture instead of the RAW format. They tolerate the long, in-camera processing time because they do not want to spend extra time at a computer converting RAW images. That is a personal decision, but in my view, the drawbacks of the TIFF capture mode outweigh its benefits. Frankly, JPEG capture, in the high-resolution/highest-quality setting of a top-rated camera, is a fine choice for most images. Use the RAW capture mode (with cameras that include this option) if you plan to make oversized prints, of even higher quality, or if you want the other benefits offered by this format. Do note, however, that most compact digicams do not offer any still-image recording option other than JPEG. Some prosumer cameras offer only a TIFF or only a RAW capture alternative. If one of these is important to you, check the specifications carefully before buying a camera. |
Visit a large photo retail store, and you’ll find three major types of digital cameras: compact models with a built-in lens, larger cameras that accept interchangeable lenses (see Figure 1.4), and even larger models designed to accept a large digital back accessory. The latter two types of cameras and their lenses are expensive, and the accessory digital backs are even more expensive. Because such equipment is primarily intended for commercial applications and studio use, I will discuss it only briefly.
| Single-use digital cameras—as well as very inexpensive low-resolution digital cameras—are also available, but these do not produce high-quality images, so they will not be covered in this book. |
Figure 1.4: Lenses such as this 15-30mm zoom are useful with a digital SLR camera for achieving ultrawide-angle effects despite the “focal length magnifier” factor.
Courtesy Sigma America
Lens Focal LengthsVirtually every digital camera—except for a few professional SLR models—incorporates a sensor that is smaller than a 35mm film frame that is a common reference standard. Consequently, any lens produces a narrower angle of view, or greater apparent magnification, with such digital cameras. That’s why you often see zoom lenses with marked focal lengths such as 7.6mm to 22.8mm in a compact digicam. This is roughly equivalent to a 37–111mm zoom lens on a 35mm camera, although the exact effective focal lengths depend on the digicam’s actual sensor size. With a digital SLR camera, the extent of the focal length magnification factor also depends on the image sensor size. A typical factor is about 1.5x, making a 300mm lens equivalent to a 450mm lens, and a 20mm lens equal to a 30mm lens. Some cameras produce a different focal length magnification factor: 1.3x or the more common 1.6x, for example, and a full 2x with the Olympus E-1 camera that employs a sensor that’s smaller than average in digital SLR cameras. This factor is useful if you often photograph distant subjects, because you may not need to buy an expensive super telephoto lens. But for true wide-angle effects, you’ll need very short lenses. That’s why short focal lengths are becoming more common, with lenses such as the 14mm, the 15–30mm, and 16–35mm zooms and the Olympus 11–22mm zoom. Most compact digicams include a feature called “digital zoom” in addition to the true “optical” zoom. When you access digital zoom, the camera crops the image electronically, saving only the central area and discarding numerous pixels. Although many cameras’ processors then add pixels, through interpolation, image quality deteriorates noticeably. I recommend against using the digital zoom feature unless high image quality is not your primary goal. |
The most common type of digital camera (see Figure 1.5) includes a built-in lens and flash unit, an LCD monitor for viewing images, and an optical viewfinder—a small window for viewing the scene—above the lens that will actually take the picture. Although cameras of this type are often called point-and-shoot models, this term is valid only for the inexpensive, basic models. Consequently, I’ll refer to cameras with a built-in lens as compact cameras to distinguish them from the larger SLR models that accept interchangeable lenses.
Figure 1.5: Compact digicams are available in many sizes, from tiny to quite large, and in various configurations.
Courtesy Fuji Photo Film USA
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Created: March 27, 2003
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