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Digital photography All-in-one desk reference 3rd edition - Busch D.

Busch D. Digital photography All-in-one desk reference 3rd edition - Wiley publishing, 2006. - 755 p.
ISBN: 0-470-03743-1
Download (direct link): digitalphotographyallinone2006.pdf
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Optical viewfinders
Most of the time, you use an optical viewfinder, which is bright and clear, uses no power, and lets you compose your image quickly. However, optical viewfinders have problems of their own, most notably parallax. Parallax is caused by the difference in viewpoint between your cameraís lens and the optical viewfinder. They donít show the same thing.
If the optical viewfinder happens to be mounted directly above the camera lens, its view will be a little higher than that of the lens itself. This becomes a problem chiefly when shooting pictures from relatively close distances (3 feet or less). Such a viewfinder tends to chop off the top of any subject that is close to the camera. Optical viewfinders usually have a set of visible lines, called parallax correction lines, which you can use to frame the picture. If you keep the subject matter below the correction lines, you can avoid chopping off heads. Of course, you get more of the lower part of your subject than you can view.
Parallax becomes worse when the optical viewfinder is located above and to one side of the lens, as shown in Figure 1-10. In that case, a double set of parallax correction lines is needed to help you avoid chopping off both the top and the side of your subject. Yuck! Here are some things to look for in optical viewfinders:
? Magnification: I get to use dozens of digital cameras in a year, and one of the first things I notice is the difference in magnification of the optical viewfinders. Put the camera up to your eye, and you might see a tiny image floating off in the distance, with the details of your scene barely discernible. Other cameras provide a big view that makes it easy to frame and compose your photo.
Figure 1-10: Parallax correction lines help you avoid chopping off heads or worse.
Book II Chapter 1
Choosing the Right Camera
104 Choosing Your View
? Zoom: Believe it or not, some digital cameras with zoom lenses have optical viewfinders that donít zoom! Ideally, the image should match the view of your LCD and lens, but some cameras keep a fixed view and use indicator marks to show the picture area.
? Parallax correction: As I mention earlier, optical viewfinders might not accurately frame the image when you move in close to your subject. The position of the viewfinder window can have an effect: If the viewfinder is directly above the lens, the side-to-side view will be accurate, but you might cut off the top of your subject if the camera doesnít provide parallax correction. If the viewfinder is immediately to the side of the lens, your problems will involve accidentally cutting off the side of your subject. Some viewfinders are both above the lens and to one side, which can produce parallax problems in both directions.
? Accurate viewpoint: As with LCD screens, the optical viewfinder might not show everything youíre framing, with some image area clipped off the top, bottom, or sides.
? Diopter adjustment: Eyeglass wearers might want an optical viewfinder that offers adjustment for common prescriptions so the camera can be used without wearing glasses.
? Extended eyepoint: The eyepoint is the distance your eye can be from the viewfinderís window and still see the entire view. Some viewfinders mandate pressing your eye up tightly against the window. Others let you back off a few millimeters, which is handy when you want to be able to see around the camera to monitor the whole scene (and not just what appears in the viewfinder) or prefer to wear your glasses while using the camera (and are thus not able to get close to the window because the glasses get in the way).
? Readouts: What information is available within and around the optical viewfinder? Some cameras show nothing but the unadorned image. Others have framing or parallax correction lines or perhaps a faint grid to help you line up the image. Perhaps some camera status indicators appear in the viewfinder, too, such as a flash-ready LED, within the field of view or located just outside the viewfinder window where it can be detected by the eye.
Electronic viewfinders (EVFs)
Some affordable cameras are available with hybrid viewfinders that work like optical viewfinders (that is, you put your eye up to a window to view your subject) but that use an electronic display to show you the image. These LCDs are much like the LCDs found on the backs of cameras, but because they are automatically shielded from extraneous light, they are much easier to view. Because they form an image by using the signal from the sensor, when compared with optical viewfinders, they offer a potentially more accurate and SLR-like picture-taking experience.
Choosing Your View 105
However, poorly designed EVFs can be a pain to use, so youíll want to examine the view through any camera so equipped before you sink your money into one. Here are some of the considerations to think about:
? Magnification: EVFs can suffer from the same viewfinder magnification issues as optical viewfinders. Because youíll be composing and (in some cases) focusing manually via the internal LCD, make sure your view is as large and sharp as possible.
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