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Haze softens sunlight, weakens colors, and brings an extra sense of depth and perspective to a scene. Depending on what you want from a photograph, you might want to reduce haze or exploit its special qualities.

Haze is the scattering of light by particles in the atmosphere. Fine dust and pollution produce it, as does high humidity. Haze varies considerably, not only in density, but in the wavelengths that are affected. The finest particles scatter the short wavelengths more than most, and produce bluish ultraviolet views over a distance. The haze from humidity, on the other hand, has a neutral color effect, and looks white over a distance.

There are two main visible effects of haze. One is on the view itself; the other is on the quality of light. The effect on a landscape is to make it appear paler at a distance; this is progressive, so that contrast, color, and definition gradually drain away from the foreground to the horizon. This effect is strongest when the sun is in front of the camera (but not necessarily low), and is what contributes most to aerial perspective – the impression of depth due to the atmosphere. To make this work strongly, however, you would need to shoot in such a way that there are at least a few obvious planes of distance in the scene; simply photographing a long view, with no foreground or middle ground, will create a pale image.

The effect of haze on lighting is to soften the hard edges of sunlight. The extra scattering reduces contrast and helps to fill shadows. The effect can be an attractive balance between sunlight and diffusion, particularly when the sun is a little in front of the camera, as in the photograph on the opposite page. The amount of haze varies as does its effects. Strong haze has much the same visible effect as light, continuous cloud.

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One of the special challenges in altering the appearance of light digitally is to create the effect of bright, sharp sunshine, but there is software available that will help. One of the fundamental question in image editing is how far you should go – that is, how far you should move away from the original as it was shot. In principle, anything and everything can be changed; in practice, it depends what you personally feel is acceptable and on how much effort it is worth to you.

With daylight photography, the major hurdle is bringing sunshine into the picture. If you have ever waited for a break in the clouds to brighten up the scene, you will know that there is a demand for this – and to an extent this can be done digitally. The problem, as you can check by comparing two versions of the same view, overcast and sunny, is that direct sunlight affects everything and in many ways, down to tiny shadows and the glow reaching into shadows from sunlit surfaces.

Although clouds reduce brightness when they block the sun, the amount depends very much on the type of cloud. If the clouds are indistinct and spread across the sky, the light loss is on a simple scale from a light haze (as little as 1/2 a stop less than clear sunlight) through thin high stratus to dark gray, low clouds (up to 4 or 5 stops darker, and more in exceptionally bad weather). With distinct clouds, however, such as scattered fair-weather cumulus, the light levels can fluctuate rapidly, particularly on a windy day. Light, white clouds usually cause a simple fluctuation of about 2 stops as they pass in front of the sun from bright to shade in one step. Dark clouds with ragged edges, or two layers of moving clouds, cause more problems, as the light changes gradually and often unpredictably.  In the first case, two light measurements are all that is necessary – one in sunlight, the other as a cloud passes – and once this is done, you can simply change the aperture from one to the other, without taking any more readings. In the case of more complex moving clouds, constant measurement is essential, unless you wait for clear breaks and use only these.

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Many of the conditions of natural light  and atmosphere can be worked on very effectively on the computer; they can be modified and even, at times, created from scratch. There are no limits to the amount of adjustment and alteration that can be made digitally to images. The most obvious of these digital techniques are those applied to the sky.

Close to the ground, atmospheric haze, mist and even fog can be poured into a scene, though to be effective the technique calls for a hands-on alteration to detail. These atmospheric conditions are readily imitated by placing a pale gray layer over the image at some degree of opacity, but the skill comes in thickening this with distance from the camera. The usual method is first to create a depth map, tailored to the particular image. These are just some of the possibilities, and if you are inventive – and can spare the time and effort – there are endless ways of tweaking the light.

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Wet and stormy weather tends to discourage photographers from going out, but it offers a range of interesting conditions, from glistening surfaces to flashes of lighting. Rain my be uncomfortable, and digital cameras, with all their circuitry, certainly need good protection from rainwater, but in terms of lighting rain makes a relief from standard sunlight. Light levels are typically low because of the thickness of most rain clouds, but the gentle, shadowless and enveloping light is good for capturing the purity of natural colors in landscapes. Greens in particular come out well on wet days, so this can be the ideal time for garden and woodland scenes.

Photographing rain itself is not easy, because of the poor light and the speed at which raindrops fall. Often, rain looks like mist in many photographs, or, if heavy, as lines. To capture actual randrops, the best conditions are back lighting against a dark background, which is uncommon in rainy weather. The best sense of raininess often comes from the subjects – such as drops on leaves and car windscreens – rather than from the light itself. The levels are usually very low; rain and cloud together easily reduce the light by 4 or 5 stops.

Lighting can add considerably to the power of a landscape. The problem is predicting it – the exact moment and also the direction. There is no way of synchronizing lighting flashes with the shutter, and the only certain technique is to leave the shutter open in anticipation of a strike. Fortunately, the electrical conditions that produce one lightning flash usually produce a number, often more or less in the same place. At the height of a storm, you should not have to wait more than 10 or 20 seconds for the net flash, and it is more likely to be in the direction of the last few flashes than in any other. Nevertheless, lightning in daylight is difficult to shoot without overexposure. If there is still light in the sky, estimate the average interval between flashes, and set the camera to allow a time exposure longer than that.

Ordinarily, the exposure depends on the intensity of the individual flash, whether it is reflected from surrounding clouds and how far away it is. You can estimate the last, at least through a group of flashes: count the number of seconds between seeing the flash and hearing the accompanying thunder. The difference is the speed of sound: a gap of fie seconds means that the lightning is 1 mile/1.6km away. Check your first exposure on the LCD screen, and adjust the aperture as necessary.

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Unless the sky is a rich, deep blue, the contrast between it and the ground is likely to be very high, to the point where it appears washed out. In landscapes and other views that included the horizon, 100% cloud cover alters the tonal relationship between sky and land. Without cloud, the difference in brightness between the two is usually fairly small; quite often, the subjects are lighter in tone. This is not the situation when cloud extends all over the scene. Then the cloud cover is the light source and, if you include it in the view, you will have a contrast problem. In other words, if the scene includes the horizon, you will inevitably lose detail either in the sky or in the ground. If the subjects or the ground are properly exposed, the sky will be white, without any visible texture to the clouds.

Many photographers simply avoid including the horizon and sky in a shot under these conditions, but you may occasionally find that you have no choice. One answer during shooting is to use a neutral density graduated filter over the lens, aligning the soft edge of the filter’s darkened area with the horizon line, so that the sky is made darker.

There is also a purely digital answer, which works best if you use a tripod and can keep the framing perfectly steady. Make two exposures, one good for the subjects on the ground, the other good for the sky (dark enough to show cloud texture). Later, in an image-editing program, the ground from one and sky from the other can be combined to get the best of both worlds.

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Clouds of different kinds, layers and thicknesses create a complex, endlessly changing arena of light.

Lighting conditions are more complicated and less easy to anticipate when clouds are broken, so that there is a mixture with blue sky. In fact the complexity extends to situations where there is more than one layer of broken cloud, each different in type. The intensity, quality, and color of light can vary. On a windy day, these conditions change rapidly, not only from cloud to direct sun, but from one type of weather to another.

If you are tying to take a particular shot that you have fixed in your mind, scattered cloud on a windy day can be frustrating, to say the least. The light changes up and down, delaying the shooting. However, the sheer variability of broken cloud can produce some of the most interesting, and even dramatic, lighting. To take advantage of it, however, you need to react quite quickly. Familiarity with the different light levels in any one situation will help; if you have already measured the difference between cloud and sunlight, you can change from the one setting to the other without having to use the meter again. Under heavy cloud with a few gaps, this may be particularly useful, as the sunlight is likely to move in patches across the landscape and be difficult to measure quickly.

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Clouds are the most visible component of weather and in outdoor photography they are by far the most important controlling factors in daylight, creating an enormous variety of effects.

Clouds diffuse daylight, softening scenes and reducing shadows. To make a comparison with a studio, they act as variable diffusers and as reflectors at the same time. Depending on their thickness, texture, extent, height, how they are arranged in layers, and their movement at different speeds, the permutations of cloud conditions are infinite. The simplest situation is when the cloud cover is continuous. Overcast skies just diffuse the light, and if they are sufficiently dense that there is no pathc of brightness to show the position of the sun, the light is as soft and shadowless as it ever can be.

Medium-to-heavy overcast skies have a reputation for bringing dullness to a scene, and to an extent this is true. Light comes more or less evenly from the entire sky, so the only shadows are those caused by obejects being close to each other; this lack of shadow reduces modeling, perspective, and texture. Objects appear to have less substantial form, and large-scale views appear flat. There is virtually no modulation of light, and the even illumination in all directions makes conditions less interesting, with none of th elighting surprises that occur when shooting in changing weather.

The value of shadowless, overcast lighting is in its efficiency rather than in its evocative qualities. It helps to clarify images. Much depends on what you see as the purpose of the shot. If the photograph has to remain faithful to the physical, plastic qualities of the subject, then this even lighting may be valuable. Clarity in the image takes precedence over more expressive qualities.

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The moon simply reflects sunlight, but very weakly. Capturing a scene by moonlight means allowing for the way we perceive it as dark, colorless and mysterious.

Photographing by moonlight needs long exposures, even at a high-sensitivity setting, as the intensity is in the region of 19 stops less than daylight. Such shots are generally worth attempting only around the time of  a full moon, with clear skies.

A bright full moon is about 400,000 times less bright than the sun. Start with a setting of about one minute at f2.8 at ISO 200, and check the result in the LCD dispaly. Such long exposures make it tempting to switch to a higher sentivity, but this increases the noise in the image and , as you will need to use a tripod in any case, it may be better jsut to make a longer exposure at the standard setting. Two other factors come into play. One is that we see moonlight as dim, and to reproduce that impression you should keep the exposure at least an f-stop or two less than normal. The other is that our night vision lacks color sensitivity, whereas the camera’s senso will pick up color as normal. Consider desaturating the image, or increasing the blue, for final dispaly.

To photograph the moon itself you will need a telephoto lens of at least 400mm equivalent to make a reasonable-sized image. The brightness depends on atmospheric conditions and on the phase. A bright, full moon needs an exposure at ISO 200of about 1/250 second at around f8, but check on the LCD screen. Other phases of the moon and hazier conditions need longer exposures. Apart from the need to avoid camera shake, keep the exposure short because the rotation of the earth causes the moon’s image to  move across the frame. You will usually need to reframe each shot.

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With the sun below the horizon, it is the afterglow that lights the scene, often with a surprising delicacy not found under any other conditions.

Like the normal daytime skylight, twilight is a reflected light source, but is rather more complex in its effects. It is the light that appears a little before sunrise (“first light”) and that remains for a short time once the sun has set. In a clear sky, the intensity shades smoothly upwards from the horizon, where it’s brightest, and outwards from the direction of the sun. (The studio equivalent is a light placed on the floor, aimed up towards a white wall, and used as back lighting.) The sky, in fact, acts partly as a diffuser and partly as reflector. The actual light levels vary considerably from a just-discernible glow to actual sunset or sunrise.

These conditions allow a fairly wide choice of exposure. If you are shooting directly towards the twilight, you can try a short exposure in order to make a silhouette of the horizon and subject. In this kind of back-lit shot, the shading of the sky from bright to dark gives some choice of exposure, particularly if you use a wide-angle lens. Less exposure intensifies the color and concentrates the view close to the horizon. More exposure dilutes the color in the lowere part of the sky, bu shows more of the higher, bluer parts. In other words, increasing the exposure extends the area of the subject within the frame. A range of exposures is acceptable, depending on what kind of effect you are trying to achieve from the photograph.

Not only does the brightness shade upwards from the horizon, but the color does also. The exact colors depend on local atmospheric conditions, and different light-scattering effects are combined in a twilight sky. At a distance form brightest area-opposite and above-the color temperature is high, as it would be during the day. Close to the horizon in the direction of the light, however, the scattering creates the warmer colors at the lower end of the color temperature range: yellow, orange and red. These merge in a graded scale of color.

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During the time in which the suns rises or set – usually no more than an hour – the light can change dramatically, revealing different picture opportunities for different lens focal lengths.

Variety and unexpected effects are the keynotes here. Whether you shoot at sunrise or sunset will probably depend on the location. You can expect the greates variety when you shoot into the sun, and few scenic locations offer a 180-degree choice of direction. Apart from the actual direction of shooting, which is obviously vital in making the photographs., the differences in lighting quality between sunrise and sunset are indistinguishable to anyone else looking at the images. During shooting, however, the times feel quite different. Fewer people are familiar with sunrise, which is a good reason in itself for shooting then – and in most locations you’ll find few people around at that time.

For dawn photography, you need to be in position at first sight. That means that you should make a recce the day before as you’ll have to travel there in the dark. The shooting experience is rather different from that at  sunset-as the light increases, the possibilities of the view reveal themselves slowly. However, because the eye is already well adapted to the darkness, you’ll find that the light levels appear much higher than they really are. If there is any movement int he scene that needs a reasonable shutter speed, you may have to wait longer than you expect in order to be able to shoot.

If you are in the habit of shooting with the white balance set to Auto, this will over-compensate for the warmer colors from a low sun, and can produce a disappointing lack of richness to the image. The daylight setting, which is balanced for 5400-5500K, will give a truer rendering of the color.
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