Basic Photography/The camera

Origins of the cameraEdit

The camera has been in use in principle since the Renaissance. It was known as the camera obscura, Latin for dark chamber, and consisted of a darkened room with a pinhole in the wall facing the subject, which would be outside the room. An inverted image would fall on the opposite wall, which would then be traced manually.

The camera bodyEdit

The purpose of a camera, whether it is a point and shoot, a view camera, digital, or film, is to project light onto a surface that will capture an image. Most cameras have the same basic controls and these controls affect how the image is recorded. The three controls are:

  • Shutter speed - The amount of time that light will be allowed to pass through the lens. The longer the camera is open the brighter an image will become.
  • Lens aperture - The size of the opening behind the lens. A larger aperture will allow more light to pass through the lens than a smaller one. A larger opening will create a brighter image
  • ISO - The sensitivity of the film to light. Traditionally this is not a camera control, but rather the type film being used. However in digital cameras, the ISO equivalency is controlled in the camera. A film with a rating of ISO 800, for example, will be eight times more sensitive to light than one of ISO 100. A higher ISO is useful in low light environments. However, increasing the ISO will affect the quality of the image: in film the images become grainy, and in digital the image becomes noisier, with more undesirable speckles.

Changing any of the settings will affect how the image looks and will be discussed later. For now let's examine different cameras and where these controls can be found.

PinholeEdit

The pinhole camera is one of the simplest cameras possible and has the three components necessary for making a photographic image. First is a light-proof box for holding the film. Second is a light sensitive material fixed opposite the third component, a hole that light passes through to expose the film. There is no lens; the aperture is created by punching a small hole opposite where the film is mounted and is very small; and the shutter is controlled manually by uncovering and covering the opening. Despite its simplicity, it still has many enthusiasts because of the unique pictures it creates and the imaginative ways of turning ordinary objects into pinhole cameras.

The camera is very easy to make, but to take pictures with it one will need access to a means of developing the film.

The principle is identical to the pioneering camera obscura experiment. Typically, a light-sealed container like a biscuit tin or a match-box can be used.

RangefinderEdit

Focus is fundamental to photography, a fact that has determined the development of the different broad types of camera. Focus is dependent upon a number of relationships, distance of the subject from the camera being the most important. A rangefinder is just that - a device to find the range of a given subject from the camera, that the camera, in turn, can be focused. Rangefinder cameras fall into two separate sub categories, those in which the rangefinder is coupled to the focusing mechanism of the camera (coupled rangefinder cameras) and those in which the rangefinder is used to determine the distance only - which is then transferred to the lens manually, clearly a less convenient, but cheaper, option.

Twin lens reflexEdit

The exact origins of the twin lens reflex (TLR) camera are obscure. Double-lens cameras were around from about 1870, when someone realised that having a second viewing lens alongside the taking lens meant that one could focus without having to keep swapping a ground glass screen for the plate afterwards, reducing the time delay in actually taking the shot.

Where the TLR came into its own was with the idea of using a reflex mirror to allow viewing from above, thus allowing the camera to be held much more steadily if handheld. The same principle of course applied to the single lens reflex, but early SLRs caused delays and inconvenience through the need to move the mirror out of the focal plane to allow light to the plate behind it. When this process was automated, the movement of the mirror could cause shake in the camera and blur the shot.

One of the earliest documented TLRs was made by the firm of R & J Beck of Cornhill, London in 1880 for Mr G M Whipple, a scientist and Superintendent of the Royal Observatory at Kew. It seems the design concept was his - to build a mirror reflex camera for cloud photography. The aim was to have a camera with lenses pointing upwards, but also to be able to compose the picture whilst looking horizontally. It seems this camera also used geared linking to synchronise the lenses, thus having many of the features of later mass-marketed TLRs .

There were a number of other types of TLR marketed between about 1890 and 1910, but these were gradually overtaken as more effective SLRs became available and cured the problem of parallax which bedevilled the TLR. The ability to see and compose the subject exactly in the taking lens outweighed the disadvantage of the moving mirror as SLR mechanisms improved.

Single lens reflexEdit

Canon EOS 500D ohne Gurt 02

As already discussed, focus is fundamental to photography, both in terms of what is and what is not in focus. A rangefinder camera, which allows one to determine the focusing distance, determines what should be in focus, but without actually demonstrating the degree. The TLR (Twin-Lens Reflex camera) goes one step further, by using a second viewing lens.

However, it is the SLR (Single Lens Reflex camera) that solves the problem fully. In this type of camera a mirror intercepts the light that passes through the lens and projects it onto a ground glass screen where it forms an erect (upright) but mirrored image. Now the photographer is truly viewing through the lens and able to accurately determine both the focus and depth of field. When the photograph is ready to be taken the mirror is retracted allowing the light to pass directly to the film, when the shutter is opened. The earliest models required the mirror to be retracted manually (this disappeared with the Speed Reflex in the mid-1920s), did not have the familiar prism of today, and demanded the viewer to inspect the image through a leather tlunnel to the ground glass screen. Another common feature of SLRs necessitated by their construction was the need for the light to pass through the lens to the reflex mirror unhindered. This lead to the focal plane shutter, where the mechanism is placed just in front of the film.

This is how most people perceive the SLR with the distinctive prism housing on top that first appeared on a Contax camera in 1948.

SLR cross section

The prism serves to reflect and flip the mirrored image from the ground glass screen to the viewfinder, resulting in an erect and true image which is bright and often magnified by the viewfinder optics. The use of 35mm film allows these cameras to be relatively compact which removed one of the SLRs drawbacks. With the shutter positioned just ahead of the film within the camera's body, it is possible to change lenses without exposing the film, making the design very flexible. The principal shortcoming is that the focal plane shutter uses a variable gap to vary the shutter speed and that only a longish exposure time will synchronise with flash.

View cameraEdit

The view camera is of either a monorail design or what is called a flat bed or field camera. The flat bed being an older design and dating back to the middle of the 19th century. In both designs a flexible bellows separates the lens and film. The lens is affixed to a front standard and the film positioned in the rear standard. Both front and rear standards can move horizontally along the rail of a monorail or on tracks in the bed in the case of the flatbed design. In most designs the front and rear standards are equipped to pivot in both the x and y axis independent of each other. These are called "swings" and "tilts". There is usually some allowance for the rise and fall of both front and rear standards along the vertical plane. All of these movements allows for great flexibility in the control of the image.

LensesEdit

What kinds of lenses, why different kinds of lenses, how do lenses affect perspective and the look and feel of an image. Some lenses are more expensive than others because some lenses let in much more light than others.

[1] How do different lenses make light bend differently? Wide-angle lenses allow a greater field of vision. Why?

"Normal" 50mm lensEdit

A normal lens, also known as a prime lens, bends light roughly the same way our eyes do, and provide an image with the proper proportions. It has a focal length close to the diagonal measurement of the image frame. That is, with a standard 35mm camera, the image on the film measures 24x36mm. The diagonal measures 43mm (sqrt(362+242)). The closest lens most manufacturers produce is the 50mm lens. Larger format cameras have normal lenses with longer focal lengths.

35mm - Nikon Nikkor 50mm f/1.4, Canon EF 50mm f/1.4, Pentax smc P-FA 50mm f/1.4, Minolta AF 50mm f/1.4, et al
645 - Pentax smcp-FA 645 75mm F2.8, et al
6x7 - Pentax smcp 67 105mm F2.4, et al
Digital APS-C sized sensor - Sigma 30mm f/1.4

The following link provides lens focal length comparisons across various film formats.

http://www.viewcamera.com/images/focalchart.gif

Wide-angleEdit

Wide-angle lenses have a larger field of view than normal lenses. In other words, they capture more of the scene in front of the camera by capturing more of the peripheral scenes. However, as the size of the film in the camera is still the same, the wider scene appears on the film as being slightly distorted: the bigger scene is "squeezed" onto the same area of film, so the typical effect is that each object is smaller (and therefore looks farther away) because the film now "includes" more objects. With each object smaller, the typical effect is that objects seem farther away. What you see in the passenger side wing mirrors in cars is the same. Those mirrors give a wide-angle effect and allows you to see more of the scene behind the car by making each object smaller, hence the warning there: "Objects in mirror are closer than they appear."

There are various wide-angle lenses, measured by the focal length. The "normal" lens for a 35mm camera is about 50mm focal length, and a wide angle lens has a shorter focal length, such as 35mm or 28mm. The shorter the focal length, the greater the perspective distortion. At the extreme end, there are wide-angle lenses with a focal length of 10mm or so using a "fish eye" projection: up to a 180 degree field of vision can be captured. However, the final photograph looks highly distorted and looks like a photograph of the scene as if reflected on a silvered ball. It may be that the name of this type of lens comes from what one imagines a fish sees under water, or that the image is distorted around a central point much like what a fish eye looks like.

[provide table of field of view angles compared to focal lengths]

Long-focus lensEdit

A long focus lens is any fixed focal length lens that is longer than a normal lens (focal length is longer than the diagonal measure of the film or sensor). This includes the common sub-type, the telephoto lens, which uses special optics to compress the length of the lens.

These lenses bring the subject in by magnifiying the subject and isolating it in the viewfinder. Lenses of this type are very useful for sports and wildlife photography for their ability to isolate a subject. However, these lenses have a drawback in that they typically are poor for low light use. Most long-focus lenses have a maximum aperture of only f/4, thus not permitting much light to reach the film and causing the use of slow shutter speeds to get correct exposure. In doing so, the photographer runs the risk of blurring the image due to his or her own movement.

One thing to bear in mind, try not to handhold your camera while using a shutter speed lower than that of the focal length of the lens being employed. This will help to assure sharper images. Using a sturdy tripod and a remote release will help a lot in low light photography.

ZoomEdit

Zoom lenses are multi-focal length lenses. A fixed lens (or 'prime' lens) has one focal length descriptor (e.g. 55mm). Zoom lenses cover a range of focal lengths (e.g. 35-105mm). A zoom lens can thus be adjusted to act as a wide angle lens all the way through to a telephoto lens.

The disadvantage of zoom lenses is that the focal complexity and number of lens elements required to achieve a range of focal lengths is much greater than for prime lenses. This is becoming less of an issue as lens manufacturers achieve higher standards in lens production. This has allowed zoom lenses to produce pictures of a quality comparable to that achieved by lenses with fixed focal length. Another disadvantage of zoom lenses is that the maximum aperture (the speed) of the lens is usually lower. This makes inexpensive zoom lenses hard to use in low-light conditions without a flash.

MacroEdit

Macro lenses have the capability to focus objects that are very close to camera without distorting the image. Generally any lens that has a magnification of 1:1 (life size) or better at its minimum focusing distance is referred to as a macro lens.

Perspective-control or shift lensEdit

When the film plane is not parallel to the surface of a subject, the subject is rendered with converging lines (lines parallel in reality are rendered converging). Typical example is when the camera is tilted upwards to photograph a building. The effect of converging lines is often unwanted and can be avoided by using a perspective control lens. It provides a function that is usually only available in view cameras: The lens can be shifted out of the optical axis (in the above example: upwards) and thus the film plane can be positioned parallel to the subject (the camera ponits orthogonally towards the building) and the subject is rendered undistorted. Shift lenses are mechanically and optically more complex than ordinary lenses, so they don't provide autofocus and they are comparatively expensive. They are usually wide angle lenses used in architecture photography.

CatadioptricEdit

A catadioptric, or mirror lens, makes use of mirrors to reflect light back and forth though the glass elements with the second convex mirror element acting as a negative lens, further extending the light cone. The result is a dramatic decrease in the length of a lens whilst still maintaining a larger focal length. Mirror lenses create tell-tale doughnut shaped highlights when a light is located in an area of the photograph that is out of focus.

Soft-focusEdit

A lens that renders the image a little softer (i.e. less sharp). This is sometimes used in portrait photography to conceal minor defects in the skin of the person. To suit this purpose soft focus lenses usually have focal lengths around 80-100mm (fFor 35mm cameras) most popular for portrait work.

FisheyeEdit

An extreme wide-angle lens. Generally refers to near 180° angle of view. See the entry on Wide-angle.please note

FilmEdit

Regular 8mm aka standard 8mmEdit

Regular 8 mm film is still available. Kodak colour film can be obtained from specialist suppliers and a Czech company (Foma) still makes black and white regular 8 mm.

Most original regular 8 cameras were clockwork powered and did not have automatic exposure or focusing. While this means any shot is restricted to the length of time the clockwork motor will run, it also means less film is wasted. Using a clockwork camera means the film maker has to plan the shots more carefully.

Technically the need not to rely on batteries can be an advantage. Reliability tends to be high as such cameras compared with electric driven counterparts are often over engineered. They do not contain the fine components of electric machines that tend to suffer over time.

Clockwork cameras are available with zoom lens, but the restrictions of a triple, double or just single lens can be beneficial to the student film maker learning the art.

With the easy availability of high tech solutions there is the satisfaction of creating movie with only basic equipment. Even more so if one processes ones own film.

Last modified on 6 November 2013, at 10:37