Normal lense
About normal lense
In photography and cinematography a normal lens is a lense that generates images that generally look "natural" to a human observer under normal viewing conditions as compared with lenses with longer or shorter focal lengths.
'Normal' lenses were once-upon-a-time standard issue with the sale of a camera. This makes them turn up regularly (some more than others) on the used marketplace, and as more people use these fixed-focal gems, the more popular they are becoming. I am lucky enough to own 18 different lenses in the 50-58mm range, and as a chronic comparer, I can't resist matching them up against one another. Even though on cropped-sensor digital SLR cameras like mine, these have a short-telephoto view, they will long be known as 'normal' - hence the Normal Lens Shootout.
Normal Lenses in Landscape Photography
It seems many photographers are in constant pursuit of exotic lenses – either mammoth telephotos, or extreme wideangles. Very few of my peers seem to use, or even own, a normal lens. The word "normal" is highly overloaded, with meanings ranging from "standard" through "typical", and all the way to downright "boring". In this age of ultra-this and extreme-that, "normal" just doesn't sound as exciting. Well, I am here to tell you that normal lenses are anything but boring. They are, in fact, some of the best and most often overlooked optics around.
Wheat Field
You may ask, what is "standard" about this lens? Why is the 50 mm lens referred to as the "standard" lens? Aside from the fact that in the past a 50 mm lens has customarily accompanied 35mm SLR cameras on purchase, there are several other reasons. Technically, a normal lens is defined as one whose focal length closely approximates the diagonal dimension of the picture frame. A 50mm lens' focal length is closest to the 43.2 mm diagonal of the 35 mm camera's 24 x 36 mm frame. Another is that its field of coverage (40° horizontally, 46° diagonally) is roughly equal to what one human eye can view with relative clarity. Even though their focal length are somewhat longer than the 43mm diagonal of the 24 x 36mm format, simply, the 50 mm standard lens gives an "honest" image because of its perspective yields, which is extremely close to faithfully close to human vision. Combine this with the fact that this lens is often successful in creating the same image of the scene that the photographer has in mind, and it's easy to see that the 50mm lens is a good basic lens. Another usual feature found in standard lenses are their high speed (maximum aperture). When that is used cleverly with high ISO film
Italian River
A "normal lens" for a 35mm camera usually refers to a fixed focal length lens of 50mm or a zoom lens zoomed in a little from its widest angle. When using a lens of this focal length, the scene looks about the same as it does to the unaided eye. With a longer focal length, everything appears closer than it actually is. With a shorter focal length, everything looks farther away
.A normal-focal-length (50mm) lens isn't necessarily the one photographers normally to use. Many photographers prefer the wider angle of view and greater depth of field provided by a slightly shorter focal length.
It used to be true that Standard lenses also doubled as a "reference lens" for respective camera/lens manufacturers. In most cases, a popular standard lens such as the 50mm f/1.4 or the f/1.8 lens was used for optical measurements at various public institutions and is also the standard which determines color balance for the rest of the rest of other lenses in the Nikkor family. Perhaps instead of "standard", a more accurate name on technical specification would be a "reference" lens. Due to the marketing aspect, for many decades, a standard lens was usually packaged with a camera in a standard purchase which could have resulted them combinely as one of the most sold optical lens in any label or brand. Because of all these qualities, those days, standard lenses are usually regarded as a starting point from which to build a lens system including wide-angle and telephoto lenses before the emergence in popularity of zoom lenses which has slowly replacing the status of 50mm as 'standard lens'. NOTE: Perspective is entirely based on camera to subject distance and actually has nothing to do with focal length. However, in practice, normal focal length lenses because of their angle of view, are usually used at "normal" shooting distances i.e. 5" to infinity. Thus, perspective tends to look "natural".
Optically, the good picture of angle in the 45-60mm focal length has resulted it to have highest number in lens types, varieties in other specialized optical Nikkor lenses. Partly due to this reason, I have set aside development of this 50mm focal length site for so long. But one fine day when a Dutch Nikon collector, Nico van Dijk mail/asked if he can offer some help for my long pending project, I just sent all my compiled materials over the last few years and invited him to patch the missing link in my Nikkor site. Although I know this could be an enormous task to create a useful references for all to use and might also take a long time to do so, but I never expect it will take such a long duration (actually, it took a span of a 6 months period). Well, I was about to think it could be another episode of die-on-natural-course- Unexpectedly, Nico came back with two complete PDF files and added some visual works comprised of his personal collection of a long list of Nikkor 50mm lenses that his owned !
If you are like most photographers just starting out with a new 35mm SLR, chances are it came with one of those ubiquitous 28-80mm (or similar) "consumer" zooms. In the last 15 years these inexpensive lenses have all but replaced the traditional 50mm prime lens as the starter optic for 35mm photographers. The 50mm lens, once the mainstay of 35mm photography, has been all but forgotten by today's photographers.
The 50mm lens is called a "normal" or "standard" lens because the way it renders perspective closely matches that of the human eye. Consequently, images made with a 50mm lens have a natural and uncontrived look. This is the lens that likely would have come with your camera had you bought it 10-15 years ago. Before falling to its current level of disfavor, the 50mm lens had a long and distinguished pedigree. For many years the defining documentary instrument of the 20th century was the small format rangefinder camera (Leica, Contax, Nikon, Canon) with 50mm lens. Some of the world's best-known photographers such as Henri Cartier-Bresson and Ralph Gibson made virtually their entire careers with this combination. With the advent of the "wide angle" Leica M2 and the rise of the SLR camera with its broad range of focal lengths, the 50mm lens began to fall out of favor among professionals users. (I hardly ever used a 50mm lens early in my career.) Today's working pros mostly eschew prime lenses for the high speed f/2.8 "professional" zooms.
Beyond their sometimes dubious optical performance, my major criticism of these lenses is their slow speed. Many of the world's most evocative and best known images were made under natural light with fast lenses and film. Creating such images is nearly impossible with "slow" zoom lenses, which are harder to focus and inadequate for use indoors without flash. Nor can they easily render backgrounds out of focus. In fact, the technical limitations of these lenses tend to lead to the kind of snapshots that the photographer presumably bought an SLR to avoid.
Standard camera lenses
Think of a standard camera lens as replicating a perspective similar to the human eye. For the most part, a standard, or normal, camera lens will suffice for general, everyday picture-taking situations such as snapshots, travel photos, individual photos, and group photos.
Majid Naghdi photographer
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The lens is an avascular organ suspended between the aqueous and vitreous humors of the eye. The cellular structure is symmetric about an axis passing through its anterior and posterior poles but asymmetric about a plane passing through its equator. Because of its asymmetric structure, the lens has historically been assumed to perform transport between the aqueous and vitreous humors. Indeed, when anterior and posterior surfaces were isolated in an Ussing chamber, a translens current was measured. However, in the eye, the two surfaces are not isolated. The vibrating probe technique showed the current densities at the surface of a free-standing lens were surprisingly large, about an order of magnitude greater than measured in an Ussing chamber, and were not directed across the lens. Rather, they were inward in the region of either anterior or posterior pole and outward at the equator. This circulating current is the most dramatic physiological property of a normal lens. We believe it is essential to maintain clarity; hence, this review focuses on factors likely to drive and direct it. We review properties and spatial distribution of lens Na+/K+ pumps, ion channels, and gap junctions. Based on these data, we propose a model in which the difference in electromotive potential of surface versus interior cell membranes drives the current, whereas the distribution of gap junctions directs the current in the observed pattern. Although this model is clearly too simple, it appears to quantitatively predict observed currents. However, the model also predicts fluid will move in the same pattern as ionic current. We therefore speculate that the physiological role of the current is to create an internal circulatory system for the avascular lens.
UNDERSTANDING CAMERA LENSES
http://www.cambridgeincolour.com/tutorials/camera-lenses.htm
Understanding camera lenses can help add more creative control to digital photography. Choosing the right lens for the task can become a complex trade-off between cost, size, weight, lens speed and image quality. This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number.
