Exposure and rendering
Camera controls are interrelated. The total amount of light reaching the film plane (the 'exposure') changes with the duration of exposure, aperture of the lens, and on the effective focal length of the lens (which in variable focal length lenses, can force a change in aperture as the lens is zoomed). Changing any of these controls can alter the exposure. Many cameras may be set to adjust most or all of these controls automatically. This automatic functionality is useful for occasional photographers in many situations.
The duration of an exposure is referred to as shutter speed, often even in cameras that do not have a physical shutter, and is typically measured in fractions of a second. It is quite possible to have exposures from one up to several seconds, usually for still-life subjects, and for night scenes exposure times can be several hours.
The effective aperture is expressed by an f-number or f-stop (derived from focal ratio), which is proportional to the ratio of the focal length to the diameter of the aperture. Longer lenses will pass less light even though the diameter of the aperture is the same due to the greater distance the light has to travel; shorter lenses (a shorter focal length) will be brighter with the same size of aperture.
The smaller the f/number, the larger the effective aperture. The present system of f/numbers to give the effective aperture of a lens was standardized by an international convention. There were earlier, different series of numbers in older cameras.
If the f-number is decreased by a factor of , the aperture diameter is increased by the same factor, and its area is increased by a factor of 2. The f-stops that might be found on a typical lens include 2.8, 4, 5.6, 8, 11, 16, 22, 32, where going up "one stop" (using lower f-stop numbers) doubles the amount of light reaching the film, and stopping down one stop halves the amount of light.
Image capture can be achieved through various combinations of shutter speed, aperture, and film or sensor speed. Different (but related) settings of aperture and shutter speed enable photographs to be taken under various conditions of film or sensor speed, lighting and motion of subjects and/or camera, and desired depth of field. A slower speed film will exhibit less "grain", and a slower speed setting on an electronic sensor will exhibit less "noise", while higher film and sensor speeds allow for a faster shutter speed, which reduces motion blur or allows the use of a smaller aperture to increase the depth of field.
For example, a wider aperture is used for lower light and a lower aperture for more light. If a subject is in motion, then a high shutter speed may be needed. A tripod can also be helpful in that it enables a slower shutter speed to be used.
For example, f/8 at 8 ms (1/125 of a second) and f/5.6 at 4 ms (1/250 of a second) yield the same amount of light. The chosen combination has an impact on the final result. The aperture and focal length of the lens determine the depth of field, which refers to the range of distances from the lens that will be in focus. A longer lens or a wider aperture will result in "shallow" depth of field (i.e. only a small plane of the image will be in sharp focus). This is often useful for isolating subjects from backgrounds as in individual portraits or macro photography.
Conversely, a shorter lens, or a smaller aperture, will result in more of the image being in focus. This is generally more desirable when photographing landscapes or groups of people. With very small apertures, such as pinholes, a wide range of distance can be brought into focus, but sharpness is severely degraded by diffraction with such small apertures. Generally, the highest degree of "sharpness" is achieved at an aperture near the middle of a lens's range (for example, f/8 for a lens with available apertures of f/2.8 to f/16). However, as lens technology improves, lenses are becoming capable of making increasingly sharp images at wider apertures.
Image capture is only part of the image forming process. Regardless of material, some process must be employed to render the latent image captured by the camera into a viewable image. With slide film, the developed film is just mounted for projection. Print film requires the developed film negative to be printed onto photographic paper or transparency. Digital images may be uploaded to an image server (e.g., a photo-sharing web site), viewed on a television, or transferred to a computer or digital photo frame. Every type can be printed on more "classical" mediums such as regular paper or photographic paper for examples.
Color photography was explored beginning in the mid-19th century. Early experiments in color required extremely long exposures (hours or days for camera images) and could not "fix" the photograph to prevent the color from quickly fading when exposed to white light.
The first permanent color photograph was taken in 1861 using the three-color-separation principle first published by physicist James Clerk Maxwell in 1855. Maxwell's idea was to take three separate black-and-white photographs through red, green and blue filters. This provides the photographer with the three basic channels required to recreate a color image.
Transparent prints of the images could be projected through similar color filters and superimposed on the projection screen, an additive method of color reproduction. A color print on paper could be produced by superimposing carbon prints of the three images made in their complementary colors, a subtractive method of color reproduction pioneered by Louis Ducos du Hauron in the late 1860s.
Russian photographer Sergei Mikhailovich Prokudin-Gorskii made extensive use of this color separation technique, employing a special camera which successively exposed the three color-filtered images on different parts of an oblong plate. Because his exposures were not simultaneous, unsteady subjects exhibited color "fringes" or, if rapidly moving through the scene, appeared as brightly colored ghosts in the resulting projected or printed images.
The development of color photography was hindered by the limited sensitivity of early photographic materials, which were mostly sensitive to blue, only slightly sensitive to green, and virtually insensitive to red. The discovery of dye sensitization by photochemist Hermann Vogel in 1873 suddenly made it possible to add sensitivity to green, yellow and even red. Improved color sensitizers and ongoing improvements in the overall sensitivity of emulsions steadily reduced the once-prohibitive long exposure times required for color, bringing it ever closer to commercial viability.
Autochrome, the first commercially successful color process, was introduced by the Lumière brothers in 1907. Autochrome plates incorporated a mosaic color filter layer made of dyed grains of potato starch, which allowed the three color components to be recorded as adjacent microscopic image fragments. After an Autochrome plate was reversal processed to produce a positive transparency, the starch grains served to illuminate each fragment with the correct color and the tiny colored points blended together in the eye, synthesizing the color of the subject by the additive method. Autochrome plates were one of several varieties of additive color screen plates and films marketed between the 1890s and the 1950s.
Kodachrome, the first modern "integral tripack" (or "monopack") color film, was introduced by Kodak in 1935. It captured the three color components in a multilayer emulsion. One layer was sensitized to record the red-dominated part of the spectrum, another layer recorded only the green part and a third recorded only the blue. Without special film processing, the result would simply be three superimposed black-and-white images, but complementary cyan, magenta, and yellow dye images were created in those layers by adding color couplers during a complex processing procedure.
Agfa's similarly structured Agfacolor Neu was introduced in 1936. Unlike Kodachrome, the color couplers in Agfacolor Neu were incorporated into the emulsion layers during manufacture, which greatly simplified the processing. Currently available color films still employ a multilayer emulsion and the same principles, most closely resembling Agfa's product.
Instant color film, used in a special camera which yielded a unique finished color print only a minute or two after the exposure, was introduced by Polaroid in 1963.
Color photography may form images as positive transparencies, which can be used in a slide projector, or as color negatives intended for use in creating positive color enlargements on specially coated paper. The latter is now the most common form of film (non-digital) color photography owing to the introduction of automated photo printing equipment.
I am Majid Naghdi a photographer
who in clines to nature an artitecture in photography , born in the 19.08.1960
i am responsible for teaching of application of equipment of professional photography to Sony sales persons for teaching of photography to Sony personnel and participants in Sony photography competitions and connected fairs and i perform Alpha seminars , too.
I have two exclusive internet site about photography - teaching equipments.
you can see their addresses here
I am one of the members of board of directors of negah photographers society.
i am one of the members of photographers or Iran society , i have photographed since i was 12 years old for 38 years.
what i have done during these years were self-tought . also i have done many researches and have studied many resources about photography at the same time.i should mention that i have photographed and have published black and white and coloured pictures , i should add that painting and designing is in my resue too.
I am experienced in maiking film,too.my first film was an 8mm animation , the voyage to moon, that was shown on television 1n the 1979 and my second film was about 5 minutes to be accepted by the youth cinema.
some of my pictures were published of Islamic revolution.
i participated in some public fairs, also i have had some them here.
I participated in "my nice city" fair , in "photographers way"fair , in "Quran" fair and in "we can" photography fair for two times.I should add that i am the photographer of the selected picture in the "manifestation of water"fairof Isfahan to be situated in Iran.
I had some pictures in the photography fair that was held in Nyrobi to be situated in kenya and some in the Banckok photography fair.
I have participated in America press photography site for three successive times and i could take points and some cash prizes.
My two last eXclusive fairs are:
1- coast to coast fair in which i had 65 pictures, about pre and post Islamic eras artitecture - modern artitecture and implicit picture , that were exhibited in the first salon of photographers house in the julay , 2008.
2- " The everlasting " fair that was about persepolis and was held in Imam Ali museum in Tehran. it was visited and encouraged by the many in the agust , 2009
فارغ التحصیل الکترونیک و عکاسی
مسئول آموزش تجهیزات حرفه ای عکاسی به پرسنل فروش فروشگاههای سونی و آموزش عکاسی به پرسنل و شرکت کنندگان در مسابقات عکاسی سونی و نمایشگاههای مربوطه و مجری سمینارهای آلفا
دارای دو سایت اختصاصی عکاسی - آموزش - تجهیزات به آدرسهای
عضو هیئت مدیره انجمن عکاسان نگاهعضو انجمن عکاسان ایران
از 12 سالگی بمدت 38 سال بصورت خودآموخته همراه با تحقیق و مطالعه عکاسی کرده و حدود 27 سال بصورت حرفه ای عکاسی مینمایم ضمنا ظهور و چاپ عکس سیاه - سفید و رنگی طراحی و نقاشی نیز شامل رزومه اینجانب میباشد.
در زمینه فیلم نیز تجربیاتی داشته
در اوایل انقلاب تعدادی از عکسهایم در نشریه رشد و مردمک چاپ گردید.
در تعدادی نمایشگاه گروهی شرکت کرده و در دو دوره عکس ما میتوانیم ودر نمایشگاه شهر زیبای من و نمایشگاه عکاسانه و نمایشگاه قرآن - نمایشگاه عکس مطبوعات و خبرگزاریها وعکس منتخب جلوه های آب - اصفهان در ایران و در نمایشگاه عکس در موزه نایروبی کنیا و...تعدادی از عکسهایم به روی دیوار رفت . سه نمایشگاه آخرم که اختصاصی و انفرادی بود عبارتند از
نمایشگاه عکس کران تا کران که 65 عکس شامل معماری قبل و بعد از اسلام - معماری مدرن و عکسهای انتزائی بود که در سالن شماره یک خانه عکاسان مردادماه 1387 بنمایش درآمد.
نمایشگاه جاویدان ایران که اختصاص به تخت جمشید داشت مهرماه 1388 در محل موزه امام علی به روی دیوار رفت که از استقبال کم نظیری برخوردار شد
.نمایشگاه ایران بارگاه مقدس که اختصاص به بقامتبرکه و امامزادگان سراسر کشورمیباشد.