Photography is all about capturing light, but not all light is created equal.   Landscape photographers in particular talk about the golden hour around sunrise or sunset when the sun is low on the horizon and the light contains more yellow and red than usual.   Unfortunately the golden hour is often more like the golden five minutes, so you often have to move fast to make use of this very warm illumination.   It's sometimes possible to compensate for the lack of good light by using filters, such as "warming" filters which can enhance a sunset or even a normal daytime photo.   However, it's very easy to overdo this effect and end up with something which looks artificial.

Tripods

    Apart from its briefness, another difficulty with golden hour photography is that while the light is superb, there often isn't very much of it.   In order to get enough for a proper exposure, landscape photographers often have to use a slow shutter speed.   Since sharpness is a highly desired goal of most landscape photography, this typically means using a tripod, since handholding the camera at a slow shutter speed causes blur.

    To figure out how slow you can go without blur, check the focal length of the lens, which is always measured in millimeters (mm).   The rule of thumb is never to go slower than the inverse of the focal length.   If the focal length of the lens is 50mm, then don't use a shutter speed slower than 1/50th of a second; if the focal length is 125mm, then don't go slower than 1/125th of a second.   If there's not enough light to take a handheld photo without getting camera shake, then you'll have to use a tripod or some other stabilizing mechanism.

    Tripods are also a vital accessory if you're doing night photography of cities, indoor architecture, or one of my own specialties, aircraft museums.

    Tripods are one of the few items of photographic equipment which are standardized across all manufacturers, so any brand of camera will fit without problems on any brand of camera tripod.

    A tripod reduces vibration caused by the motion of your body during a longer than usual exposure, but how do you avoid introducing vibration when your finger presses the shutter release on the tripod-mounted camera?   There are two main ways, either (1) use a remote control like a cable release which is physically connected to the camera, or a wireless remote control which works like a TV remote control or (2) use the camera's self-timer to automatically release the shutter when the vibrations have died down after you've pressed the shutter release.   The self-timer is cheaper and easier to use, but you have less control over the exact moment when the photograph is taken, and a cable release is much better when you put the camera into bulb mode to take a really long exposure of 15 seconds, 30 seconds, or longer.

Filters

    Using a warming filter is definitely a matter of taste, but there are two types of filter which you should consider buying for every lens in your collection.

    The first essential filter is a skylight, or its close cousin the UV filter.   A skylight is basically a clear piece of glass, while a UV filter is designed to reduce the amount of haze in photos taken of distant subjects such as landscapes.   However the main reason why most photographers have one of these filters on the front of all of their lenses is that they reduce the risk of damaging the front glass element of the lens.   Three times during my career I've dropped lenses onto the ground and had my heart sink when I've seen the front piece of glass smashed, only to discover that it was the skylight which was broken, leaving the lens in perfect condition.   Less dramatically, a skylight or UV filter will also reduce the number of scratches which the lens receives.

    The second essential filter is a polarizing filter.   These work exactly like polarized sunglasses, dramatically cutting down haze and intensifying the colors of the photograph.   They are particularly effective for photographs of the sky, turning it a deep blue and adding contrast to any clouds.   They also have a very good effect with water, eliminating most of the reflections and making things under the surface, such as a coral reef, much more visible.   There are two types of polarizing filter, linear and circular; if your camera has auto-exposure and auto-focus then you should buy a circular polarizer, because the linear polarizer interferes with these functions.   The dramatic results which this filter gives you comes at a cost - you'll lose two stops of light when using a polarizing filter.   For landscape photography this is usually affordable, but for photography with a long lens it's usually too high a price to pay, since the fast shutter speeds required mean that the aperture is already open about as wide as it can go.   Although two stops is roughly correct, the exact amount of light you lose depends on how effectively the filter is doing its job, which in turn depends on its orientation to the main light source, which when you're outside is usually the sun.

    Whenever you use a polarizing filter you should rotate it after pointing at the subject you want to photograph.   As you rotate the filter, you'll see the difference it's making; when the scene seems darkest, that's when it's having most effect, so you should take the photo with it in this position.   However a polarizing filter isn't equally effective in all directions, instead it has most effect when it's at 90 degrees to the sun or other dominant light source.   Put your thumb and first finger at right angles to each other;  if you keep your finger pointed towards the sun and at the same time rotate your wrist, the directions to which your thumb can point will be the directions where the filter will have most effect.   If you point the lens directly towards the sun or directly away from the sun then the filter will have no effect at all.

    There are several problems associated with using polarizing filters with wide angle lenses.   Since the filter's effectiveness varies depending on its orientation to the sun, part of the sky will be deep blue and part will be lighter blue, which looks strange in the final photo.   A second problem is that wide angle lenses usually have a large diameter filter screw, and large diameter polarizing filters are very expensive.   Worse yet, many very wide angle lenses don't have a filter screw at all, and the front element of the lens is often very curved, making it physically impossible to attach a screwable filter on the front.   Another difficulty which happens even with lenses which are only of medium wideness is vignetting, which refers to the corners of the photograph becoming dark and under-exposed.   This happens because the metal frame of the filter blocks part of the light entering the camera.   If the polarizing filter is mounted on top of a skylight then the problem becomes even worse, and you should remove the skylight and use the polarizing filter on its own.

Exposure Compensation

   Exposure compensation is a technique which should be in every photographer's bag of tricks.   It means overriding the camera's decision about the correct exposure for the photo, and telling the camera to let either more or less light in than it would have chosen by itself.  Exposure compensation is needed because all automatic cameras' exposure systems try to turn every photo to the equivalent of 18% grey, which is the shade of grey 18% of the way from pure white to pure black.   Most of the time this is appropriate, but if the subject is very bright or very dark then there's a high probability that the camera will choose the wrong exposure.   If your subject is a black bird like a raven, then the camera will try to turn it to 18% grey and everything else will be very over-exposed.   On the other hand, if you're taking a photo of snow or the sky then the camera will try to turn the snow or the sky to 18% grey, and everything else will be under-exposed.   In fact, dark subjects should look dark, so when photographing the raven you should dial in negative exposure compensation to tell it to under-expose the shot.   In the same way, bright objects should look bright, so when shooting scenes with snow or lots of sky then you should dial in positive exposure compensation to tell the camera to over-expose the bright subject.   Typically you would dial in around one stop (i.e. -1 or + 1) of exposure compensation, or occasionally two stops if a lot of compensation is required.

    Sometimes there just isn't enough natural light available to take a photograph, and you have to use a flash.   Unfortunately, this is far from a free ride, and there's a lot of skill involved in getting a good looking photograph while using a flash.   Some of the techniques are simple, like never pointing the flash directly towards a window, mirror or other shiny surface, in order to avoid very strong reflections from appearing in the photo.   Also, most people know that flash has a very limited range and won't help at all if you're taking a photo in a large sports stadium.   However other techniques for using flash require a lot more thought.

    The main problem with flash is that it creates very "hard" shadows, much like strong sunlight.   This is a problem in almost all photos, but it's particularly bad when you're taking portraits of people, and it's especially bad indoors, because the walls make the shadows much more visible than they would be outdoors, say in a forest.   The easiest way to deal with harsh shadows indoors is to use bounce flash, which can only be done with a flash which has a tiltable head, or with a flash which can be fired remotely, while it's not in the hotshoe on top of the camera.   In either case, take the photo with the front of the flash pointed towards the ceiling (or a wall, if that's more appropriate), rather than directly towards the subject.  Instead of illuminating the subject from a small point source, the light will bounce off the ceiling and the walls from many directions, reducing the shadows or eliminating them completely.

    Another problem with flash which most people know about is red-eye, or its animal equivalent green-eye.   In the case of humans, red-eye is caused by light being reflected off the many capillaries crossing the surface of the retina (the brain filters these out so we're not aware that these capillaries are there).   In nocturnal animals the reflection is caused by a reflective layer called the tapetum which enhances night vision.   This effect is strongest when the flash is directly in line with the lens, so getting the flash off the camera helps.   Another solution is to fix the red-eye later in PhotoShop or some other image processing software.   Some cameras perform several pre-flashes to close the subject's pupils, but this can be very distracting for both people and animals.

    One important but tricky technique to learn is how to balance flash against natural light.   This situation arises when you have illumination from both natural light and flash.   Situations when this can occur is when you're photographing a sunlit scene from inside a building or some other dark enclosed space, or when your subject is backlit and the side facing you is in deep shadow and needs to be made brighter.   The trick to balancing the flash and the natural light is to set the camera so that the sunlit part of the scene will be correctly exposed, and then adjust the flash output so it doesn't overwhelm the area you want it to illuminate.   For instance, if the surrounding landscape needs a shutter speed of 1/125th of a second and aperture of f16, adjust the camera to these settings and then turn on the flash.   If the camera has effective through-the-lens (TTL) metering, then you can allow the camera to first switch on the flash and then switch it off once the correct amount of light has hit the subject.   If you don't have TTL metering, or it's not working very well, then you can use flash exposure compensation to reduce the amount of light emitted by the flash, in the same way that regular exposure compensation can be used to adjust an exposure.   Finally, if your flash allows you to manually adjust the amount of light it outputs, then you can use this to balance the lighting.

   Night fill flash adds another complexity to this technique.   If you want to photograph a person against a brightly lit cityscape, then you'll need to set the camera on a tripod and set it to correctly expose the background - often you will need to keep the shutter open for several seconds.   Then have your subject stand in front of the camera, illuminate them using fill flash, and continue to leave the shutter open long enough to properly expose the background lights.  Of course you'll have to tell your subject to stay perfectly still while the camera shutter remains open.

    The shutter mechanism in most cameras consists of two "curtains".   When you release the shutter, the first curtain starts moving and exposes the film or digital sensor to light coming through the lens, then near the end of the exposure the second curtain starts moving and blocks the light once again.   If it's a long exposure, then there will be a period of time when the entire piece of film or the entire sensor is exposed to the light, but if it's a short exposure (say 1/500th of a second) then both curtains will be moving, one after the other, and at any one moment only part of the sensor will be exposed to the light.   Most flash units can only be used when the entire sensor is exposed, which means that there's a limit to the maximum shutter speed which you can use with flash.   If you want to use a telephoto lens and flash to illuminate birds or other wildlife, then the maximum flash sync speed might be an important factor when you're buying the camera, since you'll need a high shutter speed to prevent ambient light from producing visible camera shake.   Some cameras only allow flash at 1/90th of a second or slower, while high-end units might let you go up to 1/500th of a second.   High-speed sync is a feature where the flash pulses on and off many times during the course of the exposure, allowing the flash to be used at even very high shutter speeds.   However, much of the light falls on the lens side of the curtains rather than hitting the film or sensor, which means that much less illumination is provided for the photograph.

    There are occasions when flash illumination provides benefits over regular lighting.   For instance, the duration of a flash is extremely short, around a millisecond or less, so it can be used to stop action while still providing plenty of light.   A classic example of this is photographing hummingbirds in flight at a flower or a feeder.   The flash not only provides enough light to close down the aperture and get lots of depth of field, but it completely freezes the motion of the bird's wings and eliminates blur, and, if you make the flash the dominant illumination then the background will be completely dark, separating the bird completely from any distractions in the background.

    Another benefit for both wildlife photographers and portrait photographers is the catchlight which the flash creates in the subject's eyes.   This is a bright spot on the eye, which gives a feeling of life to the subject - without a catchlight, the eyes of a person or animal often look black and lifeless.

    All the good technique in the world won't create an interesting photo, but it will prevent an interesting photo from being ruined by unnecessary distractions.   As you master the technical aspects of photographs, you should also try to develop the principles of composition which will lift your photographs above the average.   This section contains a few ideas to get you thinking beyond the mechanics of the camera and other equipment.

   One way to improve the composition of your photographs is not to look at the subject!   Instead, look at the background and look for anything which might be distracting, such as poles, lines or branches which intersect with the subject, or things which are brighter than the subject and therefore draw a person's eye towards them.   If you see anything like this, move to the side to get the distracting element out of the shot.   For the same reason, shifting your perspective so that you're either lower or higher than head height can remove distractions.   Changing your orientation upwards or downwards often has the additional benefit that it gives a refreshing new perspective on the subject which can enliven even rather ordinary subjects, a technique which is widely used in portrait photography.

    One tried and true technique which can make outdoor shots more interesting is to frame the main subject with a tree or some other feature in the foreground to give it depth.    It's also very valuable to give thought to the sequence of events when a viewer looks at the photo.   In this shot of government buildings at one end of St Jame's Park in London, most viewers move further and further into the photo, perhaps starting with the trees in the foreground, then moving onto the water, the bridge with people crossing it, and then the buildings.   They then see how the buildings are stacked seemingly one on top of the other (an effect created by the use of a long lens).   If their eye stays on the photo for long enough then eventually they'll also see the bird nicely framed in the top, left-hand corner.   The longer you look at a photo like this, the more things you notice and the more rewarding it becomes.

    Another way to lead the viewer's eye into the photo is to have lines or curves leading inwards from the edge of the photo.   You can sometimes even have more than one interesting thing in the photo, with a subject in the foreground and an equally appealing subject in the background.   In this case, getting them both in focus can be an issue, a topic discussed in more detail in the advanced photography essay.

     Yet another approach is to have the subject placed diagonally across the frame, which is usually more interesting than a purely horizontal or vertical composition.   This can sometimes work even for normally vertical subjects like people and buildings.   In the same way, try to get a mixture of portrait (vertical) and landscape (horizontal) shots if you can.   This is difficult for some types of photography, such as aircraft or fish, since some subjects usually suit one orientation better than the other.

     Another way to lift photographs beyond the ordinary is to abstract out a very small part of the scene or the subject.   Instead of photographing a whole animal such as a bird, photograph just its eye.   It's easier for a person to apply a mental label to a complete bird and dismiss it as "just a seagull", but photographing the eye and the feathers around it forces the person to actually look at the thing for what it is, and see the beauty which is usually overlooked.