UNDERSTANDING CAMERA LENSES
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.
LENS ELEMENTS & IMAGE QUALITY
All but the simplest cameras contain lenses which are actually comprised of several "lens elements." Each of these elements directs the path of light rays to recreate the image as accurately as possible on the digital sensor. The goal is to minimize aberrations, while still utilizing
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Wide angle lenses have short focal lengths, while telephoto lenses have longer corresponding focal lengths.
Many will say that focal length also determines the perspective of an image, but strictly speaking, perspective only changes with one's location relative to their subject. If one tries to fill the frame with the same subjects using both a wide angle and telephoto lens, then perspective does indeed change, because one is forced to move closer or farther from their subject. For these scenarios only, the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective.
Perspective control can be a powerful compositional tool in photography, and often determines one's choice in focal length (when one can photograph from any position).
The following table provides an overview of what focal lengths are required to be considered a wide angle or telephoto lens, in addition to their typical uses. Please note that focal lengths listed are just rough ranges, and actual uses may vary considerably; many use telephoto lenses in distant landscapes to compress perspective, for
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These aperture ranges therefore refer only to the range of maximum aperture, not overall range. A range of f/2.0-3.0 would mean that the maximum available aperture gradually changes from f/2.0 (fully zoomed out) to f/3.0 (at full zoom). The primary benefit of having a zoom lens with a constant maximum aperture is that exposure settings are more predictable, regardless of focal length.
Also note that just because the maximum aperture of a lens may not be used, this does not necessarily mean that this lens is not necessary. Lenses typically have fewer aberrations when they perform the exposure stopped down one or two f-stops from their maximum aperture (such as using a setting of f/4.0 on a lens with a maximum aperture of f/2.0). This *may* therefore mean that if one wanted the best quality f/2.8 photograph, a f/2.0 or f/1.4 lens may yield higher quality than a lens with a maximum aperture of f/2.8.
Other considerations include cost, size and weight. Lenses with larger maximum apertures are typically much heavier, larger and more expensive. Size/weight may be critical for wildlife, hiking and travel photography because all of these often utilize heavier lenses, or require carrying equipment for extended periods of
and quality of the light, by arranging its angle and coverage.” (Millerson, pg. 16, 2013). As for the
Cameras go way back to the year 1879, and have advanced greatly throughout the years. They used to be huge and bulky with all kinds of attachments and stands. Now they are so small and thin that they are put in everyday items that we use, for instance, cell phones and laptops. Backs then cameras were less than $40 and they were made with glass that was 6.5 by 8.5 inches thick (Patti). Now in this time of age, cameras can go from a few hundred bucks to thousands of dollars depending on the camera, and they are much smaller with clearer pictures now. In 1912 Kodak came out with the Vest Pocket camera, which sold for only six dollars. It had a glass lens of 2 1/4 by 3 1/4 inches thick, which is much
For an eye to focus correctly on an object, it must be placed in a certain position in front of the eye. The primary focal point is the point along the optical axis where an object can be placed for parallel rays to come from the lens. The secondary focal point is the point along the optical axis where in coming parallel rays are brought into focus. The primary focal point has the object's image at infinity, where as the secondary focal point has the object at infinity. For people who have myopic eyes, the secondary focal point is anterior to the retina in the vitreous. Thus, the object must be moved forward from infinity, in order to be focused on the retina. The far point is determined by the object's distance where light rays focus on the retina while the eye is not accommodating. The far point in the myopic eye is between the cornea and infinity. The near point is determined by which an object will be in focus on the retina when the eye is accommodating. Thus, moving an object closer will cause the perception of the object to blur. The measurement of these refractive errors are in standard units called diopters (D). A diopter is the reciprocal of a distance of the far point in meters (Vander & Gault, 1998). The myopic condition manipulates these variables in order to ultimately make a nearsighted individual.
This is the distance from the lens to the camera sensor and is measured in millimeters. This distance helps to identify how much the lens can zoom towards an object in the frame without losing any detail. A short length leads to an image that comes in a wide-angle and captures more of the scene in your pictures. A long length creates a magnified image that comes with a field of view that is narrow. The focal lengths available with macro lenses can extend from 8-millimeters to around 400-millimeters.
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The retina is the eye’s sensor. The purpose of the retina is to receive light focused from the lens, convert the light into nerve signals, and then to send these signals on to the brain (“Retina”). The retina processes the light through light-sensitive cells called rods and cones converting the signals into colors for the brain. Rods, in which there are many of one kind, are used for low-light (night vision) and do not sense color. Cones, however, have three different kinds corresponding to red, green and blue. The different light frequencies activate the appropriate colored cell or cells to interpret infinite numbers of colors. The photoreceptors converge on the optic nerve. Images are actually perceived by the brain, not seen by the eye. It can be compared to a camera as the image is seen with film or a memory card (Richards, 2014). Additionally, the image is reflected upside down, but the brain inverts it to be right-side up. This can also be compared to the function of the camera.
This is a representation of the eye's lens system. This eye has no eye condition, such as nearsightedness or farsightedness, and the lens is drawn in its relaxed position. The light rays are focused appropriately on the retina. The thickness of the cornea is 0.449 mm, the distance from the cornea to the lens is 2.
Photography is defined at the art or practice of taking and processing photographs. To understand photography is having insight or good judgment to know how to take the picture, but also edit it if need be. Does photography limit our understanding of the world? What some people haven’t realized is that photography is all around us, whether it is in the person’s mind to see it or not. While we see photography throughout our daily routine, people dismiss the small types of photography and focus on the bigger sceneries like other countries beautiful cities and landscapes. It’s true that in this day and age, most photographs we see have been altered in some way. When photographers use Photoshop to edit our photos, we use many different ways to make that image appealing to the eye. Although, photographers unless told to do so will not change an image into something totally absurd that takes away from being astatically pleasing. Images are a gateway to the insight of the rest of the world’s cultures landscapes, and architecture, and photography is the key aspect to it. Photography is a one way to see the world, but it is better if you go and travel around the world to see it. In order to see if photography actually limits our understanding, we have to first look at the positive side of photography.
The new perspectives allow people to think differently about a situation or a person. Gaining new perspectives can help people realize the different kinds of life and allow people to understand differences.
... qualities, and focal ranges, meaning the camera could calculate the appropriate settings, which before, were a educated and process.
23 May 2014. http://www.wisegeek.com/what-are-bifocals.htm>. Glazier, Alan. A. Bifocal Glasses and Multifocal Lenses. Shady Grove Eye and Vision. Shady Grove Eye and Vision Care, 1 Jan. 2014.
+Marking a test with lots of questions about digital camera to show that what consumers¡¯ need is, what they want and what motivation cause they to own a digital camera.
What do you consider art? Paintings, sculptures, drawings, or maybe something else. I know, when I think of art, I think of photography. Photography Is used for business, science, manufacturing, art, recreational purposes, mass communication, and more. Photography is using light to do amazing things, and some people think of photography as a story that just needs to be told. Ansel Adams probably believed this. He said, “You don’t take a photograph, you make it.” Photography has a long interesting history, like the fact that the word photography is made up of two greek words, photos meaning ‘light’ and graphein which is ‘to draw’ ! Photography also has some complicated techniques to get a hang of taking good photos. Have you heard of the rule of thirds? Or do you know how a camera works? Well, that will all be explained. Maybe, by the end you will take up photography too. This essay will explore the history and types of cameras and the basic rules for taking photographs.
In Sontag’s On Photography, she claims photography limits our understanding of the world. Though Sontag acknowledges “photographs fill in blanks in our mental pictures”, she believes “the camera’s rendering of reality must always hide more than it discloses.” She argues photographs offer merely “a semblance of knowledge” on the real world.