Lens focal length is the most important characteristic of a lens. One of the prime advantages of a single·lens reflex camera or a view camera is the interchangeability of its lenses; the reason photographers own more than one lens is so that they can change lens focal length. 8230;
A lens of normal focal length, as you might expect from the name, produces an image on film that seems normal when compared with human vision. The image includes about the same angle of view as the human eye sees clearly when looking straight ahead, and the relative size and spacing of near and far objects appear normal. 8230;
Lenses of short focal length are also called wide-angle or sometimes wide-field lenses, which describes their most important feature they view a wider angle of a scene than normal. A lens of normal focal length records what you see when you look at a scene with eyes fixed in one position. 8230;
A lens of long focal length seems to bring things closer, just as a telescope does. As the focal length gets longer, less of the scene is shown (the angle of view narrows), but what is shown is enlarged (the magnification increases). 8230;
The zoom, or variable focal length lens offers several technical and visual advantages. To begin with you can just take out one lens instead of two or three of varying focal lengths. And within the limits of its zoom range you can continuously vary the size of the image-enlarging or reducing it until the right parts of the subject exactly fill the frame. 8230;
An adjustable camera controls the amount of light reaching the film in two ways. It can make the Image darker or lighter by a variable aperture. positioned behind the lens. and it can control the length of time that the light reaches the film. by a timed shutter. The lens aperture consists of overlapping movable leaves which form a diaphragm.
This can be set to a range of diameters. so that the quantity of light admitted is controlled In the same way that the width of a funnel controls the quantity of water flowing Into a container. When photographing a dimly lit subject you use a wide lens aperture to admit as much light as possible; for a bright subject you can c;hange to a small aperture to reduce the amount of light. In this way the film still receives the same amount of llght.
What are camera movements? Essentially, they are controlled independent movements of lens or film plane which enable us to form a more usefull image under a particular set of conditions. They enable us, for instance, to increase depth of field over important parts of the subject, change image shape, and use images of subjects well above, below or to the side of the lens. Camera movements offer us all sorts of image controls, from simple square-on views of mirrors without the camera showing, to a complete change in the apparent perspective of a building. Here, indeed, is valuable 8216;professional magic.8217;
With wide angle lenses covering between 63° and 115°, there is some distortion on the wider angles. For a 35mm SLR, a 35mm focal length covering 63° may not be wide enough if your standard lens is 50mm; 28mm covering 75° would be a better choice. A 24mm covering 84° is going to extremes and, unless you particularly need this coverage with its risk of image distortion, the 28mm is the most sensible all-round choice. 8230;
Altering distance and focal length. Each picture was taken with a lens of different focal length 135 mm format, but the camera distance was altered each time so that the near end of the monument remained about the same height. 8230;
Filter is optical device to remove or absorb selected wavelengths or proportion of all wavelengths. Types and description of special effects filters, close-up filters, trick filters, filters for b&w and colour. 8230;
Camera motion causes blur. Though some photographers claim to be able to hand hold a camera steady at slow shutter speeds-V8221; sec. or even slower-it takes only a slight amount of camera motion during exposure to cause a noticeable blur in an image. If a sharp picture is your aim, using a fast shutter speed or supporting the camera on a tripod is a much surer way to produce an image that will be sharp when enlarged. 8230;
Format refers to the size of film that you are using.
Medium format mostly refers to 120 film which will be 6cm wide but depending on the camera you are using can be 4.5,6, or 7cm long and even longer which would go on to a large format camera. Our cameras produce negative that are 6 X 6cm and 6 X 7cm. We would advice that you do not use 220 film as it doesn8217;t have a paper back and can rip and is difficult to load, also some of our cameras are not designed for this longer film, So please stick to 120 film.
We do have a Polaroid back for the Mamiya RS67 for this you need to buy Polaroid film.
Lots of older medium format cameras don8217;t have built in light meters and so you will most probably have to use an external light meter. Saying that we do have a metering hood and metering pentaprisim but we would advise you to use a hand held light meter.
Light Meters help to give an accurate light reading which will be converted into the appropriate shutter speeds and fno relative to the film speed ie ISO. When using a light meter first dial in the correct ISO, then set the mode to either ambient, flash non-cord or flash cord, dependant on your lighting. For a general reading point the meter at the subject from the position of the camera and take a reading.
For a brightness-range take a reading from the brightest part and the darkest part then split the difference. Using a grey-card measure the light reflected off it. For incident-light reading use the white plastic diffusing dome then meter the light that is fallin8217;g This methods will not take into account close-up work, filters on the camera or very long or very short exposures.
Most medium format cameras require you to both cock the lens and wind the film on as two separate actions unlike most compacts and 35mm cameras where both these actions are carried out simply by winding the film on.
Perspective: the impression of depth. Few lenses (except for the fisheye) noticeably distort the scene they show. The perspective in a photograph-the apparent size and shape of objects and the impression of depth-is what you would see if you were standing at camera position. 8230;
Controlling the exposure. Both shutter speed and aperture affect the amount of light reaching the film. To get a correctly exposed negative, one that is neither too light nor too dark, you need to find a combination of shutter speed and aperture that will let in the right amount of light for a particular scene and film.
The 35mm Single Lens Reflex (SLR) camera is fundamentally a 45° hinged mirror set behind a lens which reflects the image up to a focusing screen on the camera top. As the shutter release is pressed the mirror flips up to:
i) Form a seal under the focusing screen to prevent light from entering the camera through the viewing lens.
ii) Move out of the way of the lens and film. When the mirror reaches the horizontal position it fires a focal plane shutter just in front of the film to make an exposure. Distances are arranged so that the lens, mirror and focusing screen equal the the lens to film distance and everything appearing on the focusing screen is focused correctly. 8217;35mm8217; refers to the width of the film this camera uses. Each frame is a standard 24mm x 36mm format.
-The camera gives you the ability to precisely frame up the picture, focus, and observe depth of field.
-35mm types offer you the choice of fast, accurate modes for setting correct exposure by using through-the-Iens measurement of subject lighting (including flash).
-Key iformation such as correct exposure an focus, shutter speed and f-number, are signalled direct to your eye from alongside the focusing screen.
- There is a vast back-up range of lenses and accessories. This makes SLR outfits versatile 8216;unit systems8217; 8211; able to tackle most photography well.
- Fully AF (auto-focus) models adjust the lens faster than you can focus it by hand. And they work with a range of lenses.
- You cannot see through the viewfinder while the exposure is taking place. This can be a nuisance during long exposures or when panning at slow shutter speeds.
- When you are viewing at open aperture (having set a small aperture) it is easy to forget the changes that increased depth of field will give to your picture.
- The camera is electronically and mechanically more complex (and noisy) than other designs. By offering many options it tends to be more complicated to use than, say, a compact. Most SLRs also rely heavily on battery power to function.
- The range of speed settings for use with flash is limited (unless your flash gun provides a long peak.
Want to play around with SLR Camera settings and see how it affects your photo, but without actually using an SLR? Well, you can do just that with the Online SLR Camera Simulator. This simple application allows you to choose the lighting, ISO, shutter speed and aperture. A great tool to teach someone the basics of photography.
View cameras come in a variety of sizes, ranging in inches from 2 1/48243; x 3 1/48243; up to 11 x 14 formats. There are larger models, but those are usually used only for special-purpose photography because of the limits imposed by their massive size and weight. The two most popular sizes are 4215;5 and 8 x 10. All monorail cameras are modular in design. These can be specifically configured in terms of bellows, monorail length, and type of back and front components to serve a wide variety of photographic needs. 8230;
The view camera is unique because its lens and back are not rigidly fixed in one position; they can be moved readily. These movements change the relationship between the film and the lens and consequently reposition the area of sharpness or alter the shape of the subject. Each movement produces a specific effect and is defined in relation to the camera8217;s neutral position. 8230;
These movements alter the position of the image-up, down or sideways with respect to the film (Fig. 50). Identical results can be achieved with the swings and tilts combined with a change in the angle of the camera bed. There are two reasons for using the risingfalling and lateral adjustments, however. 8230;
Either the lens or the back adjustments can be used to control the plane of sharp focus, whereas the shape of the image is controlled solely by the back. Both the lens and back can be adjusted when either one alone does not provide sufficient control. However, if it is necessary to control shape and the plane of sharp focus on the same photograph, the back must be used to control the shape and the lens to control the plane of sharp focus, and the back must be adjusted first. 8230;
As the bellows on the camera are extended in order to focus and magnify the image, the amount of light reaching the film decreases rapidly. To ensure an accurate exposure it is vital to compensate for this loss of light by opening the aperture in the lens or by adding more time onto the shutter speed. This can be calculated using the following method 8230;