Cameras: Compact or SLR?
MOST precision compacts now have autofocus. In ‘active’ automatic focusing, a pattern of infrared light not visible to the eye is projected on to the subject. The angle formed by a line from the infrared source, to the subject, and back to a receptor is measured electronically and the information used to set the lens focus. This system works equally well in the dark. ‘Passive’ autofocus works by existing light and is not limited to subjects within the range of an infrared beam, but as most snapshots are taken at close range, often using flash, the active system is now the most popular.
The simplest cameras in 110 and 35mm formats are today’s equivalents of the Box Brownie. The lens is fixed focus with a small aperture for reasonable sharpness. There’s a basic flash unit built-in, film advance is manual, and exposure is set by sunny/cloudy symbols. These limitations mean that snapshot cameras are only capable of taking pictures in good light or by flash with the subject between five and fifteen feet away. They are, however, inexpensive and if you only want a camera to record the family on a sunny holiday a snapshot camera may be adequate.
These cameras are also fitted with a lens of single focal length but of higher optical quality, which means that the maximum aperture can be larger without the image becoming degraded. They may use either symbol focusing or a simple form of autofocus so the range of distances that the camera can focus sharply is increased. Superior circuitry enables these cameras to expose pictures more accurately in most seasons and weather conditions or by flash. Some models have a simple form of exposure compensation which will produce the correct exposure in ‘difficult’ lighting conditions, and a choice of ‘intelligent’ flash modes. Film loading, wind-on and rewind are all motorized. A wide choice of models is available.
This is very similar to the quality AF compact models with the difference that a choice of two ‘taking’ lenses is offered. These are often 35 and 70mm or 40 and 80mm combinations, but other variations can be found including some useful 28mm wide-angle plus 45mm standard types. Viewfinder coverage changes automatically as you switch the lens. The extra lenses increase bulk and price, but add considerable versatility. Examples of twin-lens compacts include the Nikon TW20 and the Fuji Mini Wide.
The zoom compact is more versatile and more expensive than the twin-lens compact but the versatility in focal length is produced by a single zoom lens rather than two fixed focal length lenses – intermediate focal lengths can be set. The greater the lens range, the bigger the camera becomes. Models with 35-70mm lenses are most popular, but a 38-105mm version is capable of bringing more distant objects ‘closer’. A coupled zoom viewfinder matches the focal length set. Several flash options increase the camera’s scope.
These cameras ‘bridge’ the gap between compacts and SLRs. They combine most of the versatility of an SLR with the simplicity of an automatic compact, sometimes in an unusually designed body. They have many advanced and automated features, a 3x or 4x zoom, a powerful, adjustable flash, and the ability to override the automatic exposure. The focal lengths available to bridge cameras are limited to those of the permanently attached zoom lens and are not as extensive as the choice available to SLR users. These cameras are classified as compacts but their size contradicts this description.
These cameras contain all the basic SLR features – reflex viewing, focal-plane shutter, TTL metering and interchangeable lenses – but with few further additions. The shutter, aperture, focusing and film advance are all operated manually rather than automatically. Manual cameras are very reliable because the shutter continues to operate if batteries fail – only the metering facility is lost. Their prices ranged from some of the cheapest SLRs (Zenith 12XP) to the most expensive (Leica R6).
An electronic SLR can combine manual with one or more automatic exposure modes – usually the more you pay the greater the number of options. Aperture priority auto is useful for controlling depth of field, while shutter-priority is preferable for action subjects. The simplest automatic SLRs have lever wind-on and simple dial controls, while the more advanced versions have features like integral winders and liquid crystal display panels. These cameras rely on a battery for shutter operation so you should always carry spares. Cameras of this type include the traditionally- styled Pentax P30T, the modern push-button Ricoh KR-10M, and the high-specification Canon T90. The latter uses an input wheel to speed up selecting data on the LCD display panel.
These cameras have the same features as an automatic SLR with the added refinement of auto-focusing lenses. Sensors within the camera body measure image contrast (see Lens section) and trigger motors which move the lens to sharp focus. AF technology has advanced considerably since it was first introduced and it can cope well with most situations – but certain conditions like dull light, low contrast and moving subjects may still cause focusing problems.
The AF camera retains the option of manual focusing so it is possible to overcome any limitations. Inexpensive examples are the Canon EOS 1000, Minolta Dynax 3xi and Yashica 270. The Canon EOS 100, Minolta Dynax 7xi and Nikon F-801s occupy the medium price bracket. All cameras depend heavily on batteries.
These are rugged auto or AF SLRs, designed to cope with daily use in all weather conditions – some have special water-resistant sealing. Professional SLRs may also have extra features which either increase their speed of operation or increase their versatility. The Contax 167MT and Olympus OM-4Ti are fine manual focus examples, while the Canon EOS-1 and Nikon F4 are top-ranking autofocus system cameras.
In addition to considering the options when selecting an SLR – manual or auto focus, traditional dial or push-button controls, and the number of exposure modes desired – prospective purchasers should also examine whether a camera has these worthwhile features:
DEPTH OF FIELD PREVIEW
Also called a stop-down preview, this closes down the lens to the aperture at which the shot will be taken. Although the viewfinder screen is darker, the full zone of sharpness can be seen, and a clearer idea of composition is given as background and foreground sharpness are accurately shown. This feature also provides verification of the effect of filters, particularly soft-focus, on the lens.
This enables an automatic exposure to be biased in favour of under- or over-exposure, depending on the lighting conditions. It can be set in increments of third or half stops, and two or three stops either side of ’normal’ exposure. It is used in situations when the meter is liable to be fooled (backlit, very light or very dark scenes or scenes with the sun in the picture) or to bracket exposures.
An automated version of exposure compensation is built into some advanced SLRs and the inexpensive Ricoh KR-10M. Three shots are taken – at the metered exposure, just above and just below it. Some models allow you to adjust the degree of under- and over-exposure. This feature is a way of guaranteeing at least one perfect exposure but if it is used unnecessarily you may waste a lot of film.
A button or lever disengages film advance while the shutter is cocked, enabling a further exposure on the same frame. Certain cameras like the Canon EOS-1 permit the number of exposures to be preset.
AE LOCK is a button which ‘holds’ a meter reading in memory so that a picture can be recomposed without a lighter or darker element affecting the exposure. This feature is sometimes combined with a focus lock in AF models.
(delayed action firing, putting a ten second delay in between pressing the shutter release and the camera operating) are often used by photographers to include themselves in group photographs. They also let the vibration from touching the shutter release of a tripod-mounted camera subside.
SPECIAL AF MODES
New AF SLRs have brought special features connected with autofocus and motorized zoom lenses. These include instant framing when the camera is put to the eye and aimed, and constant image-size with a moving subject, through links between focus and zooming.
SCREENS AND FINDERS
Most good specification 35mm SLRs have interchangeable focusing screens. A few, such as the Pentax LX and Nikon F4, also have interchangeable viewfinders. Nearly all rollfilm SLRs have both these features as a matter of course.
Roll-film SLRs are often modular in design, so that major components can he interchanged. This applies to viewfinders, film hacks, modes of film transport and, of course, lenses and other optical accessories. They are slower to use hecause of greater bulk and lower speed of film advance hut they are often more robust than all but the most expensive professional 35mm SLRs.
Hasselblad, Rolleiflex, Bronica, Mamiya, ami Pentax are the major manufacturers, each with a range of cameras (in several formats in the last three cases). These cameras are rarely chosen by amateur photographers because of their lack of automation, high cost and heavy weight.
This is a traditional design employing a pair of matching optics, arranged vertically. The top lens is linked to the viewfinder, while the lower one exposes the film. Because you see a view slightly above that photographed, these cameras aren’t recommended for close-up work, but the lack of a mirror mechanism makes them quiet. The are frequently used by wedding photographers because expressions can be watched without interruption. Twin-lens reflex cameras are available from Mamiya, Rolleiflex, and imported from the east. With second-hand twin-lens reflexes, names like Yashica and Minolta can he added to the list.
These cameras bring medium-format quality in relatively lightweight packages, but they are not as common as SLRs. Few components are interchangeable, so their construction is more compact than modular roll-film cameras. The range-finder focusing Mamiya 6, for instance, accepts three compact lenses, but cannot switch backs or finders.
Cameras can be constructed like an optical bench, with lens and film standards linked by a light-tight bellows and provided with movements so the lens or film can be tilted, raised, lowered or swung. Studio cameras are built on a rail, with extensive movements. ‘Field’ cameras fold out from a portable box, with a baseboard instead of a rail, and have limited movements. Wooden field models are popular due to their light weight.