There are numerous detection devices available and choosing the right one to protect a particular area isn’t always easy. There is a whole range of circumstances to take into account — the size of the room, what’s in it, even how it is constructed, as well as what’s outside or even across the road.

You may need one or more types of detectors in any one area — for example, there are bound to be doors and windows to protect as well as the room itself. There may also be very large areas of glass, such as a patio door, draughts or heating, which may make it difficult to site certain types of detectors, and you may have pets in the house which will mean careful positioning and directing of the detection pattern.

Magnetic contacts

The most basic detection device is a magnetic contact (or reed switch). The reed switch is attached to the fixed section of an opening (i.e. frame of a door or window) and is held in the closed position by a magnet fitted to the moving part. When the magnetic force is removed by the door or window being pushed ajar, the switch opens, cutting off the current (if the alarm is set) and triggering the alarm.

Contacts should be positioned carefully, ideally at the top of the door, with the contact flush mounted in the architrave a few inches in from the catch side of the door. Surface mounted contacts, easier to fit, are often provided with DIY kits. One is sufficient for each opening but it is important they are installed on well fitted and sound frames or you may end up with false alarms.

Detecting shock

Shock sensors come in a variety of forms — inertia, piezo electric and vibration. These are designed specifically to detect force and sounds like splintering wood in the area that is being protected. Once again, it is very important to position these correctly.

Pinpoint the most obvious point of attack, where the intruder may gain access with the least noise; on a window this is likely to be close to the handle where the intruder may try to lever the window open. The sensor should be mounted on the window frame and set at a sensitivity level where it will not trigger the alarm other than when a real attack is detected. You should also check that other sources of vibration, like a nearby road or railway line, will not affect the device.

Independent tests on a correctly fitted vibration sensor showed that it didn’t react when the window was tapped, a door knocked or a tennis ball thrown against an adjacent partition. Even a masonry drill used on an external wall about a metre away did not activate the alarm.

Glass break

The problem with glass break detectors is that not all types will work effectively on double-glazing. There are basically two methods. Self adhesive foil strips or tape carrying a current can be applied to the glass. Breaking the tape triggers the alarm (although even a hairline crack can produce this and cause false alarms).

A single strip should be applied no nearer than 30cm (12″) to the edge of the glass; the glass is held firmly and any nearer may not shear the foil. If a rectangular pattern, rather than a single strip, is used, then it must be applied no less than 50mm (2″) and no more than 10cm (4″) in from the edge. It also has to be varnished to insulate it from moisture.

The other method is based on audio (ultrasonic) technology and enables the detector to recognise the particular frequency of breaking glass. Here it is important not to position a detector close to air vents or doors where the noise of glass breaking outside may be picked up, or placed near a telephone.

Laminated glass may also reduce the effectiveness of the device. However, one system is able to measure the flexing effect of a blow on glass as well as the frequency it generates, so glass breaking outside should not create an alarm. These units can also be used to protect several windows at a time, rather than having to fit a device to each window separately.

Panic buttons

A personal or panic attack (PA) button has to be activated deliberately by a person in the house. Usually it’s by pressing a hand button, although it is possible to obtain adapted units which can be activated with a knee or foot (often used by retailers, banks and similar premises or by the disabled). The unit activates the alarm via a special 24 hour circuit even when the alarm has not been set and can only be turned off and reset with a special key. PA buttons should be sited as discreetly as possible and are often positioned just inside the front door and by the bed.

Pressure mats

These aren’t widely used today but are often included in DIY kits. Available in various sizes, they are suitable for protecting staircases (one may be positioned at the top or bottom of the stairs), immediately inside patio doors or other possible points of forced entry. Pressure mats incorporate an ‘open’ circuit which is completed when the intruder steps on the mat. It is necessary to have the underlay of the carpet cut away to avoid the mat showing — an expensive measure if you have to employ a carpet fitter to do it for you.

You should be careful not to place furniture on them by mistake or to install them on uneven floors or on top of carpet tacks or other sharp objects which could pierce the plastic covered mat. They are prone to wear, which could result in a false alarm, and if placed under a thin carpet may eventually show.

Passive infra-reds

The most popular of the movement detectors is the passive infra-red detector (PIR). PIRs look for a change in energy — the infra-red produced by humans — and trigger an alarm if the source of the energy (body heat) moves across a fan-shaped series of zones. In older PIRs, strong sunlight could trigger the detector but most now incorporate a dual sensor system which has zones on two levels so, if the source of heat is static, it should be ignored. Only if the heat source moves across the PIR‘ s range should an alarm be triggered.

PIRs are supplied in a choice of ranges — long, wide, corridor and curtain — and can cover as little as 3m (10′) up to as much as 40m (about 133′). The long and corridor lenses have fewer zones across a narrow width but can detect movement as far as 30 or 40m away. The curtain type is suitable for protecting doors or windows and particularly large areas of glass. The pattern is a vertical one running parallel with the area to be protected and creates a solid protected zone. These are also useful if the house is open plan with a mezzanine floor for the bedrooms. The pattern would be able to detect anyone jumping off the mezzanine or a break-in through the ceiling from a loft.

Pet alley patterns allow an area at ground level for pets to walk around safely without triggering the alarm. However, this means that an intruder crawling by would not be detected and it also doesn’t prevent pets jumping on to furniture and setting off the alarm. The only way really to avoid this risk is to keep dogs and cats, and any other warm-blooded animals likely to roam, confined to one room where a movement detector is not in use. A room protected by contacts or shock detectors would also be secure from pet false alarms.

Some PIR detector manufacturers now supply masks with a standard scanning unit which enables the coverage pattern to be modified to prevent the PIR from seeing ‘hot spots’. You can adapt them to different circumstances rather than having to buy completely different units.

PIRs are susceptible to moisture — ensure that those used to control exterior lighting, for example, are IP rated. This is a grading system which shows the level of resistance to dirt and moisture; they should be at least IP44 to IP55. Insects, too, can cause havoc if they get into the casing or even walk across the sensor if the optics aren’t sealed. PIRs should also be resistant to radio frequency interference (RFI).

There are no specific British Standards for control panels (or alarm devices themselves), although elements of BS 4737 relate to features found in alarm equipment. This is likely to change with the introduction of European Standards which will, for the first time, require individual components to meet levels of performance and construction.

It is very important to understand how an alarm system is operated if false alarms are to be avoided. To reduce this risk, manufacturers have been making instructions easier to follow and many panels now incorporate a Liquid Crystal Display (LCD) giving plain English step- by-step instructions to guide users through the arming, resetting and disarming procedures.

Precautions to prevent tampering are also built in. The control panel should incorporate an anti-tamper device to deter anyone from trying to prise the lid or attack it in any way. Each zone, the wiring and detectors will also be protected from attack, triggering the alarm if there is any interference with the system.

The control panel will also feature a device to set the alarm and turn it off. This may be a keyswitch (operated by key only) or a keypad, where you will need to use a code (usually four digits) to carry out any procedure.

Most panels allow you to divide your home into zones and set all or part of the system. It will also enable you to set the entry/exit time delay. This is the amount of time you have to enter and turn off the alarm or set the alarm and close the door behind you. It will vary but can be as little as two seconds to over a minute.

Make sure it is set to give you enough time to enter or exit the front door (or your final exit) and disarm/arm the system. The delay will be signalled by a sounder and can instill panic if you have forgotten the code or can’t find the key to turn the panel off before the alarm sounds!

The panel will also contain an alarm sounder of its own and should have a 12v rechargeable stand-by battery to take over powering the alarm, for at least eight hours, in case of a power cut. If a primary battery is used as a stand-by, it must be able to run the system for four hours to comply with BS4737. If this runs out, however, it will trigger an alarm condition.

The alarm panel will operate using a 230v mains supply — you should never see a professionally-installed wired alarm panel with a plug attached. It should always be wired in. In addition, alarm panel cabling and existing mains wiring should never be run in the same trunking.

The trend today is to have the control panel hidden away, perhaps in a cupboard, where it is out of sight and not immediately accessible to an intruder. The system will have one or more remote keypads positioned at prominent places around the house which can be used for all the day-to-day programming . Usually not much larger than a light switch, they provide an attractive and discreet system which is relatively easy to operate.

Detectors

The most popular type of detector to protect complete areas — rooms and hallways — is a passive infra-red device (known as a PIR). Also essential to the system are magnetic contacts (small, flush or surface-mounted devices which protect doors and windows) and one or more personal attack buttons which activate the alarm in an emergency even when it is switched off.

Personal attack buttons usually have a red circular or rectangular push button which triggers the alarm and can only be turned off with a special key.

Other devices used may be ultrasonic or, rarely used alone in domestic situations, microwave. Some detectors now combine two of these technologies, typically PIR plus microwave, in an effort to reduce false alarms, and these are proving very successful in difficult environments.

A very important addition to an alarm system is a smoke alarm. There are smoke detectors which can be wired into an alarm system (the latest Building Regulations specify smoke alarms as a standard requirement in new and newly converted homes) or you can buy a battery-operated smoke alarm, easily fitted.

Monitoring

Most modern panels are able to provide a means of monitoring the alarm. A special device called a digital communicator is installed in the control panel and is able to send a digitally encoded signal, via a normal telephone line, to the central monitoring station.

For an alarm to be acted upon and a message to be passed to the appropriate emergency services (police, fire or medical), the receiving equipment must receive and acknowledge the correct sequence of signals.

Bells and sounders

The bell box can be of polycarbonate or, for high security applications, produced in aluminium and treated steel and powder coated. (BS4737 requires the housing to be of 1.2mm mild steel, 1 mm stainless steel, 3mm polycarbonate or equivalent.) Bell boxes should be fixed as high as possible on the house front and may now include a strobe light which will continue to flash after the bell has stopped ringing after the statutory 20 minute maximum period.

The alarm should also trigger if the bell box is tampered with. This is caused by a self-actuating bell module (SAB) which, if the mains cable is disconnected or cut, will bring in its stand-by battery to sound the alarm.

Bell boxes are also increasingly being fitted with a separate timed cut out (from two to 18 minutes approximately) so that if the SAB takes over operation of the sounder, it does not continue to ring, unless automatically reset by the system, for longer than 20 minutes at a time.

There is a good reason for this. If an alarm is considered to be constituting a statutory offence under The Environmental Protection Act (Section 80), local authorities have the power to fine the owners of the alarm up to £5,000. The Noise and Nuisance Bill increases these powers to enable officers to enter premises under certain conditions.

In addition, the London Local Authorities Act can oblige owners of offending alarms to fit cut off devices. This applies as much to DIY systems as to professionally installed ones, so beware.

As well as being fitted with anti-tamper devices, bell boxes may also have an anti-foam device which activates the alarm if foam is pumped into the box through the louvres at the side. Some bell boxes are being produced without louvres which also overcomes the problem.

Personal recommendation is probably the best way to choose a company to install your alarm system.

Then, if the installation or system should prove unsatisfactory, you do at least have an official organisation to approach to take up your complaint and investigate the situation.

You should obtain at least three quotes from reputable installers and remember — the cheapest may not necessarily be the best value.

Wired or radio system?

The system offered to you should include a control panel, possibly a remote keypad, detectors (which may include passive infra-red units, magnetic contacts, vibration sensors, ultrasonic sensors or glass-break detectors), a sounder and bell box with a strobe light attached, and personal attack button.

Communication between the main panel, detectors and alarm bell box of traditional alarm systems is normally via special security cabling and powered by the mains electrical supply. Radio, however, means you can install an alarm faster and more easily and you can take it with you if you move.

You can now obtain virtually any form of detector with a radio alarm, and kits tend to contain a selection with additional units available for you to buy separately as and when you wish to expand the system.

In fact, a good radio alarm manufacturer should be able to supply you with a transmitter capable of adapting any detector for use with a wire-free system. These include magnetic contacts, passive infra-red detectors, glass-break detectors, personal attack buttons and smoke alarms.

You will also have a remote hand-held unit (like those used to operate car alarms) which is used to activate and turn off the alarm.

Terms and conditions

Before you part with your cash or sign a contract, make sure you know whether you are leasing or buying the system outright, whether a maintenance agreement is included in the price and ensure that a 12 month guarantee is offered on parts and labour.

Make sure there are no hidden costs, such as call-out charges or a monitoring service you didn’t know about, and find out exactly who is doing the work — whether the company sub-contracts and whether staff are vetted.

Above all, make sure you understand exactly how the system works once it is installed.

The installer should talk you through all the elements of the system and its operation and make sure you can operate it correctly before he leaves. He should also leave you a card or a manual describing the user facilities and the action you need to take.

If you or a member of your family are in any doubt whatsoever make him show you again or explain it more clearly. A very large proportion of false alarms occur simply because the owner doesn’t know how the alarm system works.

Doing it yourself

If you do not have to consider insurance company requirements and simply want the peace of mind an efficient alarm system can bring, you may consider installing the alarm system yourself.

There are two ways of approaching this: buy a kit or choose the components yourself. If you buy an alarm in a box from a security centre or one of the major DIY superstores, it should comply with BS6707. Check that it contains both sufficient cable and detectors which will suit your home and protect areas in the right way; also that the overall quality of the components is good.

It is also reassuring to know that the manufacturer provides a ‘Help hotline’ in case you get into difficulties. Read the instructions very carefully, particularly those relating to wiring, and check that all the listed components are actually there before you begin.

Another way of choosing an alarm system is to visit your local security centre and ask them to make up an alarm kit for you. Not all security centres offer this service but you may be find one that will either issue you with a set of instructions for fitting or be prepared to answer any queries over the telephone.

Unfortunately, neither the police nor an alarm monitoring station will accept emergency calls directly from a DIY alarm system. Nevertheless, you will still have to notify the police that the system has been installed and give them the names and addresses of two keyholders.

Some DIY systems come equipped with an automatic dialling device which, if the alarm is triggered, repeatedly telephones a series of numbers you have chosen until it receives a reply and is able to send a recorded alarm message. Well worth considering if you have elderly or disabled relatives living in the house.

Alarms have improved considerably in recent years and, if used and installed correctly, should give trouble-free and false alarm-free operation.

False alarms have been, and continue to be, a problem and may sometimes be the reason for home-owners preferring not to install a system or even taking one out if it proves unreliable. It can also attract unwelcome attention from irritated neighbours and disgruntled police.

The most important additions to the camera outfit are the extra lenses. If you have always used a standard lens on your camera, you may not find it easy to decide which would be the best lens to buy next. Obviously, you want to start with the one that will be the most versatile for your type of photography. As a first buy, most photographers choose a wide angle lens (28mm) or a telephoto lens (135mm). If you like taking scenic landscape pictures or you want to include a wide area without having to step back with the camera too much, then a wide- angle lens is a good choice. A 28mm lens is the most popular type of wide angle. Lenses of 24mm and wider give more image distortion and can give an interesting special effect but, with care, they can also be of general use. For portraits, sport and other general types of photography, buy a 135mm telephoto lens. Most of them are lightweight, easy to use and reasonably priced. Later, you can invest in a longer focal length lens (200mm or more) for distance shots.

On the other hand, many photographers now buy a zoom lens as an alternative which means that they get, in effect, three or more lenses in one compact unit : which also means there’s less weight to carry about. Both wide angle to normal (28-50mm) and short- telephoto to long-telephoto (80- 210mm) zoom types are available, and some even offer a close-up, ‘macro, setting. A zoom lens may well be cheaper than a set of three or four lenses of fixed focal length.

Some independent lens manufacturers make interchangeable mounts so that, if you decide to change your camera later on, you can keep your lenses and simply buy another mount.

Camera supports

A tripod, or a similar form of camera support, is essential for any long exposure shots. There are many tripods on the market, from table-top models to heavy-duty studio stands. Look for one which is sturdy but lightweight and portable (most are made of aluminium). Quick release legs and an adjustable pan and tilt head are useful features. Simpler and more portable camera supports include a monopod (a single leg tripod) or a G-clamp, which attaches to a table or similar surface and has a tripod screw to support the camera in any position.

Looking ahead

As your photography develops you may want to add items such as a flashgun for indoor photography or fill-in lighting outdoors, or perhaps a motor-drive for fast action photography, if your camera will accept one. At a later stage, you could get an extra camera body, so that you can shoot black and white and colour at the same time, or use two different lenses without having to keep changing them. But remember to buy only the items that you will really need, otherwise you could end up with a gadget bag full of expensive hardware which you never use.

Hiring equipment

It is always worth discussing with your local photographic dealer the possibility of hiring certain items—either for very occasional use, or before you decide to buy. You may feel that the high cost of a long telephoto lens or a more powerful flash unit would not be justified by the number of times you would use it.

Insurance

Once you start accumulating valuable equipment, it is wise to consider insuring it all. Although there are separate policies for camera equipment, most companies advise amateurs to add their equipment on to an existing household contents policy. With an `all risks’ extension, the equipment should be covered for accidental loss or damage, even on location. But check with your insurance company, or a broker, for more details.

Smaller items—a blower brush for cleaning lenses, or a cable release, for example—also form part of the serious photographer’s equipment as the collection builds up. And, of course, you will need a gadget bag, or a carrying case to keep everything in.

The right priorities

Don’t be put off by the vast array of camera accessories on the market— you won’t need them all. Obviously you need to sort out priorities and decide what to buy now and what to leave for later. This will mainly depend on:

• Your style of photography. Think about the items you really need to help with the type of photography you concentrate on, be it landscapes, portraits, still life or sport.
• Your budget. A cheaper item, such as a filter, can open up new fields, even if you can’t yet afford to invest in more expensive extra lenses.

Inexpensive basics

First, think about the smaller items for the outfit. A lens hood (rubber or metal) not only protects the front of the lens from damage but helps to prevent ‘flare’ when shooting towards the sun. Camera shake can be a problem, so a cable release is useful whenever long exposure times require the camera to be mounted on to a tripod or support. Camera care equipment, such as a blower brush, lens cleaning tissue and even a small screwdriver set for on-the-spot repairs (a loose screw on the lens, for instance) all have a place in the outfit too.

Camera bags

You will need some sort of carrying bag for these first basic accessories. At first a medium-sized soft shoulder bag is enough to carry the camera, lens hood and filter, spare film, lens cleaning tissues and hand-held exposure meter—if your camera has no TTL metering. It is helpful if the bag has an outside pocket of some sort to keep the small items from getting damaged by the bulkier ones. Just make sure the various things are well wrapped in dusters to stop them banging about. Some people keep their camera in its ever-ready case.

As you add more items to your outfit a special camera carrying case is more suitable. Most are made from reinforced real or simulated leather, and contain cut-outs or removable inserts to secure various pieces of equipment. Most have carrying handles as well as shoulder straps, so that the case can be carried easily while you are taking photographs.

There are various ways you can make sure your equipment is securely held in the case, and overleaf we show how a typical camera bag can be adapted to your precise needs.

Finally, and very much for the larger outfit, there is a range of more expensive aluminium attache cases with foam rubber inside, which can be cut to hold the equipment firmly. These offer good protection, but they can be the most expensive. Avoid the cheaper ones made of foil-covered plywood which is lighter, but does not offer as much protection. Bear in mind that, because these aluminium cases are brightly finished, they tend to be conspicuous—and may possibly attract a thief.

Choosing filters

There are many different types of filter on the market, but the basic outfit need only contain four or five. Most photographers start off with a simple skylight I A filter which cuts through ultra violet ‘haze’. Unlike a normal UV filter, it is also colour corrected, so it can be used for black and white or colour film. The skylight filter can be kept on the camera all the time to stop dust and dirt spoiling the lens.

A polarizing filter will counteract reflections from glass or other similar surfaces, darken the sky, and make colours more vivid.

Various coloured filters–red, green, blue, yellow—can be used for effect in black and white work. In a landscape shot, for instance, a yellow filter will make the sky darker, an orange filter will exaggerate the effect, while a red filter darkens the sky still further. With colour film, these filters give an overall colour cast to the picture, which can be effective.

Colour correction filters are useful for either colour negative or transparency film. They enable you to take daylight pictures with tungsten (artificial light) film, and vice versa.

So a few filters will make a worthwhile yet reasonably inexpensive addition to your camera outfit. You might want one or two of the simpler special effects filters, as well. The starburst turns a single light source into a repeated star shape, and a soft focus filter can be used to soften portraits.

The lens-to-camera attachment is very important on SLR cameras. It must be easy to fit, light-tight, and link up smoothly with the camera’s controls. There are two basic types of lens mount—screw thread and bayonet. Screw thread mounts: found on the older or less expensive SLR models. Their great advantage is standardization. All screw thread lenses fit any make of 35mm camera body made for this type of lens mount.

Bayonet mounts: this mount is much quicker to use and is supplanting screw thread. Unfortunately, each manufacturer has a slightly different system, but most specialist lens makers can supply adapters to suit the different models and fit them for you.

Disadvantages

There are times when an SLR is not the best camera to have, but these tend to be specialized situations. The focal plane shutter and the movement of the mirror make the camera noisy. During exposure there is a momentary loss of the image in the viewfinder—a problem during long exposures. It has more moving parts and is, therefore, more susceptible to damage from rough handling than a viewfinder camera. The shutter cannot synchronize with flash at high speeds (useful when using flash in daylight).

An SLR outfit is more expensive to insure and does require you to take care of it, but most of the equipment can be traded in at a good price if you decide to change to a newer camera. And, with this system, you can often keep a favourite lens adapted for use with the new camera body.

Although heavier and bulkier to carry around, especially with more than one lens, than the 35mm rangefinder cameras, the SLR is still remarkably compact for its performance. All the accessories, as you collect them, can fit into a purpose-made gadget bag and can bring within the grasp of the average photographer a wide range of subjects previously considered to be confined to the specialist.

Before buying an SLR

* Do you want lenses which screw on to the camera body or which have bayonet mounts? Bayonet is faster, but screw thread lenses are generally cheaper.

* Do you want built-in, through the lens metering or a hand-held exposure meter? It is better to buy a camera with TTL metering and get a hand-held meter later on.

* Do you want to be able to change the focusing screen for a different type, or is the one seen in the viewfinder easy for you to focus sharply?

* Some cameras are heavier than others, some are now very much smaller. The larger, heavier models tend to be more robust, but the lighter, more compact ones are easier to carry with you. Try the camera and controls to make sure they are comfortable and in the right place for you.

* There are two types of focal plane shutter. The modern, electronic shutter works vertically and is often made of metal. It will synchronize with flash at 1/125. The older, rubberized cloth type, although quieter, works horizontally and can only be used with flash up to 1/60. If you are planning to use flash in daylight the vertical shutter is better.

* Is the image in the viewfinder bright enough and easy to focus, and is the exposure information displayed clearly?

Are you going to want to add a motor-drive or autowind unit at a later stage? Maybe you would like to be able to use the camera with a bellows attachment for nature photography or in a laboratory.

Does the camera have a depth of field preview button? This allows you to see the effect of the aperture before the shutter is released.

The Leica M4-2 is a rangefinder camera with a full range of lenses. Leitz produced the first 35mm camera in 1925. Built with great precision, the camera was light and gave high quality results on the motion picture film then used. The design evolved to include a full range of lenses, coupled rangefinder, shutter speeds from 1 second to 1/1000, exposure meter and reflex housing for telephoto lenses. All lenses now feature a bayonet mounting system.

The advantage of this type of camera is that it is small, quiet, robust, and there is no loss of the image during exposure. Some people find it easier to focus in poor light.

The lenses you can buy range from 21mm to 135mm, focused through a coupled rangefinder. Framing marks in the viewfinder appear automatically as the lenses are changed, including automatic adjustment for parallax. Longer telephoto lenses focus through a reflex housing.

There are many earlier interchangeable lens viewfinder cameras still being used today, alongside similar models like the Contax or the Canon. The other cameras made of this type are Russian—the Kiev and FED44—and are available at low cost with lenses from 28mm-135mm.

A camera which is reasonably compact, easy to operate, and can take a whole range of lenses opens up dozens of new possibilities for any photographer. Telephoto lenses for sports action pictures and better portraits, wide- angle lenses for depth in sweeping landscapes and pictures in cramped spaces, or close-ups of insects using a macro (close-focusing) lens. The pentaprism SLR camera can provide all these things. It is the most popular interchangeable lens camera, widely used by amateurs and professionals alike. There are others with interchangeable lenses—for example medium format SLR cameras and some viewfinder cameras—and these are discussed in detail later on.

Special features of the SLR

The advantages of the SLR camera to the enthusiast are enormous. It is unrivalled for flexibility and can be used in nearly every photographic situation. If you can afford it, there is a lens, filter, or accessory to fit each occasion; but every SLR camera has certain basic features which make this flexible approach possible.

The range of lenses: when you buy a 35mm SLR camera it usually comes with a lens of about 50mm focal length. This photographs a view familiar to the human eye and is called a normal or standard lens. But on either side of the 50mm lens there is a large number of lenses extending to wide angle on the one hand, and telephoto on the other. First start with a 40-55mm standard lens and get used to the camera before deciding on your next lens. Your choice of an additional lens will depend on the sort of pictures you really like to take. Are they portraits, buildings or landscapes, close-up photographs of flowers and insects, or recording the excitement of sporting events? The answer will help you choose your next lens, but always buy the best quality you can afford.

The viewing system: the SLR has a unique viewing system. The image in the viewfinder is the same image seen by the lens. The viewfinder shows how much of the subject will be photographed, whether the lens is focused correctly, and the effect of the chosen f number or a filter. In fact, you can preview the finished picture before pressing the shutter. A pentaprism (five-sided prism) mounted between the viewfinder and the focusing screen shows the image both right way up and right way round, whether the camera is held horizontally or vertically.

TTL metering: exposure metering in art SLR camera can share the advantages of seeing through the lens by taking the light reading through it as well. This feature is called through the lens or ‘TTL’ metering. Instead of using an external ‘eye’ the TTL meter reads from inside the camera system and thus works perfectly with all types of lenses and attachments.

Exposure control: getting the correct exposure is a combination of f number (aperture size) and shutter speed for the amount of light available. To help the photographer most SLRs have a built-in exposure meter which measures the brightness of the light entering the lens. The right choice of shutter speed and f number will make a needle in the viewfinder line up with a marker (or a small light shine). The exposure is then correct.

A large number of SLRs have automatic exposure control which makes things even simpler for the photographer. There are two kinds of automation : aperture priority and shutter priority. Both have their advantages and the one you choose depends on the sort of photographs you want to take.

Aperture priority tends to suit still subjects in which accurate control of depth of field is important, such as landscapes and portraits. It is up to the photographer to set the f number he wants, and the camera automatically sets the correct shutter speed.

Shutter priority gives the photographer control over the shutter speed—a better solution for capturing movement. Once the shutter speed is set the correct aperture is selected automatically and shown in the viewfinder. Some of the most expensive and sophisticated models have both shutter and aperture priority settings. You can switch from one setting to the other at the flick of a lever, getting the best of both worlds.

Even on cameras with automatic exposure control there is usually some provision for manual override. Once they have some experience, many photographers feel that they like to have total control over the camera’s choice of settings.

Many SLRs with built-in meters still have manual control of aperture and shutter. You set the shutter speed to suit your subject-1/125 for still subjects and up to 1/500 for something moving—then alter the aperture settings until the exposure meter needle (or signal light) in the viewfinder indicates the correct exposure. This works equally well if you set the shutter speed first.

Most modern cameras make it impossible to make a double exposure unintentionally. But sometimes double or multiple exposures provide unusual and interesting results.

A few cameras have a switch or lever to allow the shutter to be retensioned without advancing the film to the next frame. This makes accurate register of the subject components possible and gives the most successful multiple exposures.

Some cameras with this facility also manage not to advance the frame counter. If your camera’s frame counter advances every time the shutter is cocked, make sure to make a mental or written note that one or more of the frames is double or multiple exposed so that you don’t take the film from the camera before you have used ever frame. This means that the fram counter may indicate frame 38 on a 3 exposure film for example.

Pressing in the rewind release button: while advancing the film wind-on leve may be possible with some 35mn cameras without a multiple exposure device. This cocks the shutter but as the film take-up spool sprockets are thus disengaged the film does not move to the next frame. There is a risk that the film may move slightly which could alter the composition, or may even cause overlap with the next frame. Try the technique first with a test film. You will enjoy greater success if you operate the film advance lever slowly and gently.

Cable release socket

The shutter release of many cameras is internally threaded to accept most makes of cable release and long air release. On a few cameras the cable release socket may be found elsewhere, such as on the side of the lens housing. The cable release can be used for timed exposures with the shutter speed dial set to ‘13′ (the long time setting which holds the shutter open all the while the shutter release is depressed). Some releases can be locked to hold the shutter open for long periods—several minutes or hours.

Many photographers use a cable release whenever the camera is mounted on a tripod. This reduces the risk of camera shake when using slow speeds.

It is also helpful to use a cable release for a complicated set-up. This means you don’t have to find room to work your hand between camera and nearby lights to fire the shutter, and eliminates the danger of disturbing camera, lights or subject. You may also get better portraits if you remove your eye from the viewfinder after focusing and composing and fire the shutter with a cable release. This tends to put the subject more at ease.

Delayed action

Delaying the tripping of the shutter for several seconds after pressing the shutter release has several advantages. The photographer can mount the camera on a tripod and take a self- portrait, or perhaps include himself in a group photograph. He might also set up a photograph (perhaps a candid shot) and walk away while the exposure is made. As well as helping with shy subjects this can be used to prevent the photographer’s shadow from appearing in the picture.

Some cameras have a variable delay, usually between two and 10 seconds. Many cameras use a clockwork timer to regulate the countdown time, while others have a totally silent electronically controlled rundown, often monitored by a flashing red light on the front or top of the camera body.

On some cameras it is possible to cancel setting of the delay either before or during the countdown period, but on others, once the delay mechanism is set you are obliged to use it. Make sure you know what type of delay timer is fitted to your camera.

For cameras with no built-in timers a mechanical delayed action device can be purchased separately. It attaches to a cable release, or can be screwed into a cable release socket, and you can set the delay you want.

Flash synchronization

Most 35mm cameras have flash contacts built in to their accessory shoes on the top plate. They are called hot shoe contacts, and do away with the need for a separate cable to connect the flash gun with the camera shutter.

The metal pins should be kept clean to provide good contact for the flash gun —hot shoe covers are inexpensive items. Focal plane shutters must be set at the correct synchronization speed, usually around 1/60.

Most SLR cameras have a separate coaxial socket to accept a sync cable from an electronic flash gun. This allows more versatile flash lighting because the flash can be removed from the accessory shoe by using an extension sync cable. The coaxial socket is usually marked ‘X’.

Sometimes it is possible to use two flashes—one mounted on the accessory shoe and one connected by sync cable—to fire simultaneously. Check this with the camera handbook first. `FP’ sockets are seen less frequently these days, but refer to older type flash guns and flash bulbs. X and FP sockets delay opening of the shutter until the flash has reached the peak of its light output.

Knowing how to use all the features provided on your camera helps you get the most from your equipment. If you are not sure what a particular dial or lever is intended for, this probably means that you have not read (or were not provided with) the handbook.

If you are not sure of something, spend some time going through the operation of the control with the handbook.

Even the most accurate through the lens exposure meter can be fooled by a subject surrounded by large dark or light areas, subjects which are predominantly back lit, or those against unusual backgrounds. These can influence the meter, providing false information about the light level. Thus the main subject is over-exposed if the meter reacts to a large expanse of black background and, conversely, underexposure of the subject results if it is back lit or surrounded by a large bright area.

Some cameras have a built-in exposure memory which ensures that the subject is given the appropriate exposure to show detail regardless of the surroundings. To use the memory facility effectively take a meter reading close up to the subject, or even from a substitute object of the same tone as the main part of your photograph, and lit in the same way.

Often the exposure reading is taken by gentle half-way pressure on the camera shutter release button—this activates the meter circuits. Holding the button in the same position while moving away to photograph the entire subject keeps the camera set to whatever aperture and shutter speed have been preselected during close-to light metering. The exposure is made without releasing this gentle pressure on the shutter release.

The disadvantages of this method are that if you ‘let go’ the memory is overriden and you are back to square one. Care must also be taken neither to release the pressure sufficiently for the camera meter to take its reading from new information, nor to squeeze a little too hard, trip the shutter and waste a frame. This type of exposure memory or exposure hold is most commonly found on 35mm non-reflex cameras. Some sophisticated cameras have a special memory button which is less precarious to use. The memory button may be the type which is held in once the light reading has been made; or some electronic cameras retain the exposure memory for several seconds after once pressing the memory button. In the latter case a viewfinder light signals that the memory is in operation.

Exposure compensation

Many automatic SLR cameras have a means for overriding the meter’s settings to compensate for ‘difficult’ lighting conditions with certain subjects. This is usually in the form of a dial providing two full f stops compensation over and under that set. The settings are often graduated in 1/3 or ‘1/2 stop steps and can either be marked –2, – 1, + 1, + 2 or x , x1/2, x2, x4. In both cases the respective settings indicate two stops less exposure, one stop less, then one stop more and two stops more exposure than that set. For back lit subjects, or subjects against a bright background the dial should be set to plus (that is more) compensation. This provides detail in the main part of the subject and the amount of compensation required depends on the amount of back light. A dark background or large dark unimportant areas of the picture seem to occur less frequently, but minus compensation (by giving less exposure) gives full detail in the main or lighter parts of the subject.

Some cameras have back light compensation only, and this often provides fixed 11/2 stops more (plus) exposure. If your camera lacks the EV (exposure value) compensation dial you can

EV compensation scales are usually only found on automatic SLR cameras. The Chinon CE-4 gives ±one stop and only the 1/3 stop steps are marked. The Contax 139 can provide ±two stops compensation achieve the same degree of exposure control, and more, by adjusting the film speed dial. Move the film speed indicator to half the ASA of the film in use to increase exposure by one full stop. For example if you are using 100 ASA film, set the film speed dial to 50 ASA. This tells the camera that less sensitive film is being used so the built- in meter automatically compensates. Doubling the film speed setting decreases the exposure given by one full stop—if you are using 100 ASA set the dial to 200 ASA.

It is of course vital that the dial is returned to its correct setting when returning to ‘normal’ photography with lighting which needs no compensation. Some cameras have a signal in the viewfinder to show when dial-in compensation is in use, but there is no signal to remind you that you have adjusted the film speed dial. If you forget to readjust the compensation control or film speed dial subsequent frames will be over- or under-exposed.

This is usually found on a camera top plate. The index shows the exact location of the film within the camera and thus enables accurate measurements and calculations to be made. It is most useful for close-up work when you may want to measure bellows extension or extension tubes to help you work out magnification and exposure. Close-ups are difficult to focus with a non-reflex camera because the focus cannot be checked through the viewfinder. Instead the distance from the subject to the film must be measured accurately. Some cameras which do not have a film plane index have a serial number engraved on the top plate. The top of the figures often corresponds to the location of the film plane inside the camera.

Battery check

With so many modern cameras depending on electronics, battery power is vital. It is a good idea to test batteries from time to time, especially since silver oxide and manganese alkaline types last for so long and then suddenly give up. Use the battery check button before each main picture session, but do not be tempted to overdo the testing or you may drain the batteries prematurely.

If you don’t have a checking facility, most manufacturers recommend that camera batteries are replaced after a year of normal use. If you are in doubt about battery condition, replace them. Never store equipment for more than about one month with batteries inserted—they may leak and corrode the inside of the equipment.

Rearsight features

Many viewfinder rearsights are fitted with grooves or a screw-in collar to accept accessories such as a right-angle finder. They also accept eyepiece correction lenses which help the spectacle wearer.

Spectacles can be a nuisance and prevent the photographer from getting his eye close to the finder and therefore from seeing the entire screen from corner to corner, including exposure information. The back of the viewfinder can also scratch spectacle lenses. Fitting a dioptric correction attachment to the rearsight, which exactly matches your spectacle prescription, is a possible solution. They are available from some camera manufacturers to suit a range of long- and short-sighted vision, but can also be made by an optician if special correction is necessary. Some SLR cameras have a limited range of correction built in to the rearsight.

Many automatic metering cameras have a small shutter which can be moved over the inside of the viewfinder eyepiece by operating a lever. The shutter prevents light from entering through the eyepiece and affecting the exposures. This is more likely to happen when the camera is mounted on a tripod or being used on delayed action when the photographer’s eye is not there to shade the eyepiece. The meter cell inside the camera responds to this extra light and it may result in under-exposure. If your camel doesn’t have an internal eyepiece blind you can probably buy an external cover which clips into the viewfinder rearsight grooves (if provided). An alternative is to make your own blind from opaque card or tape.

Spectacle wearers can overcome the problem of light entering the eyepiece because of the distance between eye and viewfinder being greater than for non-spectacle wearers by buying a rubber eye-cup. The cup screws or clips on to the rearsight, and although it won’t eliminate light entering from behind the camera, it will reduce it and in addition makes use much more comfortable.

Film memo holder

A simple way of reminding yourself what type of film is loaded in your camera is to slip the end of the film carton into a special size frame which is provided on the back of many cameras. Forgetful people without film memo holders could quite easily tape the carton end to the back of the camera or slip it into the ever-ready case. Some cameras have an adjustable dial which you can set to remind you whether you have loaded black and white or colour film, and whether it is balanced for daylight or tungsten light.

There are many different exposure controls which may be included on your camera apart from shutter speed and aperture selectors. Here you are shown exactly how to use them.