I'm always window shopping on ebay, seeing for some great deals on lenses. If I had unlimited funds I'd tell you what lenses I'd like to have; they are written on a board over my desk. I've researched what I need for the kind of photography I do, but I find most population don't know what to look for when seeing for a lens for their camera. What do all the numbers and letters mean on the record of the lens?
The advantage of having a Dslr is the potential of using dissimilar lenses specific to the dissimilar types of photography that one does. Living where we do there is microscopic occasion we'd ever undoubtedly get to see the most recent lens that has come out. We have to read reviews of population who have tested out what we're interested in. Still, it is prominent to have some basic knowledge of lenses in order to be an informed consumer.
Af S Dx Nikkor Zoom Lens
Lenses can be whether a particular focal length (prime) lens or a zoom lens which has a range of many focal lengths. Prime lenses tend to be of good potential than zoom lenses because there are compromises when designing lenses with many dissimilar focal lengths as opposed to designing a lens with a particular focal length. It is difficult to say sharpness throughout the lenses full zoom range. normally image potential degrades in zooms as they are extended to the longer focal lengths. up-to-date computer designing of zoom lenses has improved their quality. Though zoom lenses are very favorite I gravitate to my favorite prime lens when I want to be assured of a sharp image. It is prominent to note that most lenses are sharpest in the middle of their cleft range. The irregularity to this are lenses with large maximum apertures ( f1.4, 1.2, or 1). This is because these lenses are designed to be used at these maximum apertures. I think it is prominent for beginners to use a prime lens because it soldiery them to think more about how to use just one view to make their photographs.
Lenses are also classified as wide angle, general and telephoto. You can have wide angle, telephoto, or midrange zooms too. How they are classified has to do with the film or sensor size. What is determined a general lens for a 35mm camera is a telephoto to a camera with a smaller Aps (Dx) size sensor or a wide angle to a larger medium format camera. Since there are many dissimilar sensor formats (sizes) many times focal lengths are talked about as 35mm equivalents, (what the focal length would be for a 35mm camera). Lenses are measured in focal lengths by millimeters. A general lens is one where the angle of view is close to what we normally see with our eyes (50mm). A wide angle lens is one that encompasses a wider angle of view than we normally examine (50mm).
All lenses are made to acquire and focus light onto a specific point. They also have an iris that controls the whole of light allowed to pass through the lens. The iris is made up of thin blades that are put together and adjust to form dissimilar sized openings. The iris in our eyes is round but the iris in the lens is undoubtedly a polygon because it is made of hard edged blades. The more blades that make up the lenses iris the smoother the circle of the iris will be and the smoother the out-of-focus areas will appear. This out-of-focus smoothness is called the lenses bokeh (bow-kuh). Higher potential lenses will have more blades in their irises.
So what dissimilar kinds of lenses are there? Talking in 35mm camera equivalents here, wide angle lenses are those with focal lengths under 50mm. A 28mm lens is a moderate wide angle whereas a 14mm is a fish eye with an extreme angle of view. With a fish eye lens you have to make sure your feet aren't in the photo when shooting. Telephoto lenses are ones with focal lengths longer than 50mm. Portrait lenses fall in this category. Somewhere around a 90mm lens is good for a ¾ portrait, where a 180mm is nice for a head and shoulders portrait. If you want to get not so close but still personal with wildlife you should start with something like a 300mm and go for a 600mm if you undoubtedly want to stay incognito to the grizzly grazing on the side of the hill. potential telephotos are very expensive because there is a lot of big glass in them and they are as long as your arm.
So what do all the letters and numbers mean on a lens? In catalogs the focal length is mentioned first with the maximum cleft next along with the filter size in parentheses. So you have 50/1.8 (52), meaning it is a 50mm (normal) prime lens with a f1.8 maximum cleft and a 52mm filter size. If it was 28-200/3.8-5.6 macro (62), it would mean that the lens was a zoom that's focal length was wide angle to telephoto with a maximum cleft of f3.8 @28mm and f5.6 when zoomed out to 200mm and the screw in filter size would be 62mm. It is also designed for close focusing manufacture it a macro. One thing you will observation is that when the maximum cleft whole is smaller the price of the lens goes up. A 50mm 1.8 might be 0, a 50mm 1.4 lens jumps to 0 and a 50mm 1.2 is well over 0. The presume for this is that in order to get more light through the lens the glass needs to be bigger and the make more complex. If you often need to photo at f1.2 with your 50mm lens because of low light or you like the narrow depth of field then it's worth the money. On the other hand if you very seldom open up to the maximum cleft you are wasting your money. As with most tools, those that are designed for one specific task are good than those that are made to do many tasks.
Many lenses have macro (close focusing) features but there are lenses specially made for close-up work and their potential is better. The longer the focal length of a macro lens the greater working length there is from what is being photographed. Perspective control (Pc or shift) lenses offer the potential to compensate for lens distortion when photographing buildings. Architectural photographers use these. There are portrait lenses that are soft focus or offer defocus control for those who desire softness or nice bokeh to their images. Mirror telephotos offer an inexpensive alternative to expensive long lenses. They are much shorter and lighter because they have less glass and a mirror in their design. potential is marginal and they have a fixed cleft which is normally slow meaning you can't use them in low light. The lens' bokeh will also be rendered with circles because of the mirror.
Some other acronyms on lens descriptions are: If, internal focusing (the lens doesn't rotate and expand while focusing), Af, auto focus, Vr or Is, vibration allowance or image stabilization feature built into the lens so it is possible to hand hold your camera using slower shutter speeds. Ld, Ed or Apo glass, low dispersion, extra low dispersion glass or apochromatic glass (lens elements that are designed to focus the dissimilar wavelengths of colored light onto the same plane). You might also see mention of aspherical lens elements. Lenses are typically sections of a sphere. Lenses must focus light onto the flat plane of film or a digital sensor while our eyes must focus onto the back of our eye, which is also spherical. In order for light to be focused on to the flat plane of film or a digital sensor lens elements are made aspherical to compensate for the diffraction of light through the lens.
Many top of the line lenses have very quiet motors that run the auto focus. You may see Usm (ultrasonic motor) on Canon lenses and other mentions of quiet focusing on other brands.
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