Understanding camera lenses to more creative (PART.2)

By Rephopy Mar 15, 2010 0 comments
A zoom lens is one where the photographer can vary the focal length within a predetermined range, whereas this can not be changed to "prime" or fixed focal length lens. The main advantage of the zoom lens is that it is easier to achieve a variety of composition or perspective (due to changes in the lens is not required). This advantage is often essential for a dynamic subject matter, such as in photo journalism and photography of children.


Keep in mind that using the zoom lens does not mean that no longer have to change their position; raise only increases flexibility. In the example below, the original position is shown along with the two alternatives using the zoom lens. If the main lens is used, then the change in composition would not have been possible without cutting the image (if desired strict composition). Similar to the example in the previous section, is achieved by minimizing the change in perspective and getting closer to the subject. Or, to achieve the effect of the opposite perspective, one could have enlarged and moved further from the subject.

Why would one deliberately limit their choices by using the main lens Prime lens existed long before zoom lenses are available?, And still offer many advantages over their peers are more modern. When the zoom lens first arrived on the market, people often have to be willing to sacrifice a large number of optical quality. However, newer high-end zoom lenses usually do not produce a visible image quality is lower, unless they are scrutinized by a trained eye (or in very large print).

The main advantage of the main lens is the cost, weight and speed. Cheap prime lenses generally can provide picture quality as good (or better) as a high-end zoom lens. In addition, if only a fraction of the focal length range required for a zoom lens, the lens shape with the same focal length will be significantly smaller and lighter. Finally, the best prime lenses almost always offer better light gathering capability (the maximum aperture is larger) than the fastest zoom lens - often essential for low light sports / theater photography, and when a shallow depth of field is required.

For compact digital cameras, lenses listed with the title, 3X 4X, zoom, etc. refers to the ratio between the longest and shortest focal length. Therefore, a larger zoom designation does not necessarily mean that images can be enlarged again (because of the zoom which may only have a wider angle of view when fully zoomed out). In addition, digital zoom is not the same as optical zoom, as only the former enlarge the image by interpolation. -Read the fine print to make sure you are not misleading.


The range of the lens aperture refers to the amount that can open or close the lens to let more or less light, respectively. Holes are listed in terms of f-numbers, which quantitatively describes the relative light gathering area.

Note that the aperture opening larger f-numbers are defined as having a lower (often very confusing). Both terms are often mistakenly interchanged, the rest of this tutorial refers to the lens in terms of their aperture size. Lens with a larger hole is also described as "fast," because for a given ISO speed, shutter speed can be made faster for the same exposure. In addition, a smaller aperture means that objects can be in focus over a wider range of distances, the concept is also called depth of field.

When someone is considering buying a lens, the specifications usually list the maximum (and probably least) holes are available. Lens with a greater range of aperture settings provide greater artistic flexibility, both in terms of exposure and depth of field options. The maximum aperture lens aperture may be the most important specifications, which are often listed on the box along with a focal length (s).

Portraits and indoor sports / theater photography often requires lenses with maximum apertures very large, to be able to narrow depth of field or shutter speed is faster, respectively. Narrow depth of field in portraits help isolate the subject from their background. For digital SLR cameras, lenses with larger maximum apertures provide the viewfinder image is significantly brighter - it may be important for night and low light photography. It also often provides auto-focus faster and more accurately in low light. Manual focus is also easier because the image in the viewfinder has a narrow depth of field (thus making it more visible when objects get into or out of focus).

The minimum hole for the lens is generally nowhere near as important as maximum apertures. This is mainly due to the minimum hole is rarely used because of blurred images from the diffraction lens, and because it may require a prohibitively long exposure time. For the extreme case where the depth of field is desired, then the smaller the minimum aperture (a larger maximum f-number) lens allows for a wider depth of field.

Finally, some zoom lenses on digital SLR and compact digital cameras often list a variety of maximum aperture, because this may depend on how far one has been zoomed in or out. These range aperture as it only refers to the maximum aperture range, not the overall range. Various f/2.0-3.0 would mean that the maximum available aperture gradually changes from f/2.0 (fully Stars) to f/3.0 (at full zoom). The main benefit of having a zoom lens with a constant maximum aperture is that the exposure settings are more predictable, regardless of focal length.

Also note that just because the maximum aperture the lens can not be used, this does not mean that this lens is not required. Lenses usually have less distortion when they perform exposure stopped down one or two f-stops from their maximum aperture (such as using the settings on the lens with f/4.0 maximum aperture f/2.0). It * may * because it means that if someone wants the best picture quality f/2.8, f/1.4 lens af/2.0 or can produce a higher quality than the lens with f/2.8 maximum aperture.

Other considerations include cost, size and weight. Lenses with larger maximum apertures are usually much heavier, larger and more expensive. Size / weight may be important for wildlife, hiking and photography trips for all frequently use heavy lenses, or require carrying equipment for a long time. Sharing is sexy

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