 BetterPhoto Member |
Zoom photography for modest budget/skill Is there a way to relate the optical zoom ratings on compact digital cameras (e.g. 8 X optical, etc.) to the ratings on DSLR zoom lenses (e.g., 35mm - 70 mm)? Should I even be trying to? I need the most zoom possible without spending thousands for professional equipment or having to attempt to develop considerable expertise. I'm willing to work at learning how to use the equipment and so on, but it probably isn't going to become my passion. I will use it in a variety of conditions, daylight, bad weather, nighttime, etc. I will primarily use it to increase my stock of photos of transportation equipment (trucks, trains, ships, etc.; sometimes parked, sometimes moving) to incorporate into PowerPoint for use in safety training programs. I can't always get up close but sometimes the details of the small markings on this equipment is relevant to the subject of the training class. Will also use as a family camera (e.g., youth basketball, baseball, family gatherings, etc.) Budget is approx. $1,000. Wondered if one of the new things I think are being called "megazooms" or "SLR-type" might be useful. Any advice would be appreciated. Thanks
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John G. Clifford Jr |
Most small point-and-shoot digital cameras, or 'digicams', will have their focal length range reflected in 35mm terms. For instance, the Canon G9 has a 7.4-44mm lens, which equates to a 35-210mm lens on a 35mm camera. Obviously, that reflects a 6x zoom range. If you're not sure which camera to get, look at sites like dpreview.com; they have lots of reviews on digital cameras of all sorts, and you should be able to find a camera that's right for you there.
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Alan N. Marcus |
All camera lenses bend light inward to form a miniature image of the outside world by projection onto the surface of a sensor chip or film at the back of the camera. The distance from about the center of the length of the lens barrel to the surface of the sensor of film is measured and defined as the focal length (when the camera is focused on a distant subject). The focal length determines the size of the image formed. An image produced by a 100mm lens is 4 times bigger than that produced by a 25mm. If the camera is equipped with a zoom lens 25mm ~ 100mm, this would be called a 4x zoom. This value is the range of change with regard to focal length. Today’s digitals also sport an electronic zoom. This provides additional magnification that is generated by clever software inside the camera. While effective, electronic zoom produces substandard images as compared to optical zoom. If the optical zoom is 4x and the electronic zoom is 4x, the combination magnifies 16 times, written as 16x. We are taking about zoom range. Image magnification: It is customary to fit cameras with a lens with a focal length approximately equal to the diagonal of the picture. For the venerable 35mm film camera this measurement is 43mm however by tradition they are likely fitted with a 50mm lens. When so fitted the perspective that results about matches the human experience. Such a lash-up (any format fitted with a lens equal to the diagonal measure) is expressed as magnification 1 or 1x. The angular field of view will be 53°, also the human experience. Because usage of the 35mm film camera is prevalent, most books and teachers affirm 50mm as magnification 1x. Thus if a telephoto is mounted with a focal length of 200mm, the camera is said to be operating at a power (magnification) 4x. Most D-SLR’s built for the professional are sized to equal the 35mm film camera. The chip size measures 24mm by 36mm. We are talking about the full frame sensor variety. APS-C variety: Should you be aware? A little knowledge of cameras and lens won’t do you any harm. Alan Marcus (marginal technical gobbledygook)
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