Low Light Camera Settings

 Key Camera Settings for Low Light

         Cameras’ menus vary widely, and use different terminology, but if you have a digital SLR to reasonable specifications, be conscious of all the following settings.


 Image quality and format

         The arguments for shooting Raw are stronger than ever in low light shooting, not least because it allows some latitude for recovering highlights and shadows, and allows you to defer decisions about color temperature until post-production.

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 White balance

         The importance of this setting depends entirely on whether or not you shoot Raw. If you do, then it hardly matters what you set at the time of shooting, although most people prefer to have the image preview on the camera’s LCD screen looking more or less correct. Opinions vary, but my default preference is Auto. If, on the other hand, you are shooting JPEG (with Raw for example), then constant attention to the choices in the White Balance menu is necessary.



         Low contrast is always safer, as it is easier to increase later in post-production than to recover lost highlights and shadows. Many low light situations feature high contrast, especially those with light sources in the frame. If shooting Raw, this does not matter, as contrast is applied after capture.


 ISO sensitivity

         This is likely to be the key control during low light shooting that you will access and change regularly. The flexibility offered by instantly switchable ISO settings is one of digital photography’s biggest boons.


 Long-Exposure Noise Reduction

         Because Long-Exposure Noise Reduction is independent of the subject, in-camera processing is ideal. Check the camera manual, but choosing to set it to “on” will not affect shooting at normal shutter speeds. It will kick in at a specified exposure time; again, check the camera manual to see what this is for your model. At exposure times longer than this threshold, processing time doubles, because the automatic procedure involves creating a “dark frame” of the same exposure time, then subtracting the noise pattern in this from the previously exposed image. If you make a 30 second exposure, for example, you must wait another 30 seconds before you can shoot again. See here for more details.


 High-ISO Noise Reduction

         High-ISO Noise Reduction works specifically on chrominance noise. It analyzes the image looking for small, near-pixel-sized areas of color that don’t share the same color values as the larger surrounding areas. It then shifts the color values of the discolored areas so that they blend in with the background, so reducing chrominance noise without blurring detail. High-ISO Noise Reduction is only applied to JPEGs, although if you shoot Raw the file is tagged with the High-ISO Noise Reduction “marker” that will, when you convert the Raw file, inform the Raw editor to apply High-ISO Noise Reduction. However, you need to check that whichever Raw editor you’re using can recognize the marker.






         Nikon menu offering both Long-Exposure Noise Reduction and High-ISO Noise Reduction options.




         Some cameras offer auto bracketing, in which a burst of exposures gives frames under- and overexposed in addition to the metered exposure. This consumes storage space on the card and takes extra time when shooting, but if you feel uncertain about the exposure setting in some situations, it can be a useful backup (and you can always delete the unwanted exposures later if you need to).






         Adjusting the Auto Exposure Bracketing to the nearest third of a stop on a Canon menu.






         The Sony menu allows the user to set limits for the automatic ISO adjustment.


 Display choices


         Because many low light scenes contain bright local lights and pools of light, it is useful to know when these are being overexposed. The most useful display for this is the highlight clipping warning, in which overexposed areas (where the photosites have filled up to their maximum values) are superimposed with a flashing warning. Some people find this distracting, but it is also valuable. A histogram is also particularly useful in low lighting situations, not least because the LCD screen image looks relatively brighter when the surrounding light is low. The danger of this is that if you judge exposure simply by this appearance, the image is likely to be underexposed. Viewing it on the LCD screen later in normal lighting is likely to deliver an unpleasant surprise.






         This screen simulates the clipping warnings that would be visible on screen as the shot is captured. The green area is the clipped highlight warning, but the remaining colors are displayed accurately.



 Natural Low Light


         Low lighting conditions divide usually into those of daylight and those of artificial lighting. The normal maximum daylight is outdoors, in the middle of the day in clear weather.


         As we’ve already seen, this is in the order of 50,000 lux or more. While it’s probably going too far to say that the manufacturers of cameras, lenses, film, and sensors assume this to be the standard, what most people would call bright daylight is the ideal condition technically. This was the “sunny 16” rule, from the days when many photographers would estimate settings, and it holds that the usual exposure on a sunny day is 1 over the film/sensor speed at f/16 (thus 1/100 at f/16 at ISO 100).


         What counts as low natural light sets in when it becomes difficult to guarantee sharp images with a normal lens and low ISO sensitivity. In practice, this means when it becomes difficult to either hold the camera steady, or freeze a normally moving subject at maximum aperture without taking special precautions such as fitting an unusually fast lens. There is no exact point, but this is somewhere around several hundred lux. Even during full daylight hours, thick cloud cover, rain, snow, and storms can reduce light levels to this low level. However, all we are talking about here are the technical difficulties as weather conditions such as these can deliver expressive imagery. Essentially, this is extreme diffusion, and so with cloud cover the color temperature is affected only a little. With something more unusual, like a sandstorm, the color can shift radically, as the example on the left illustrates.






         A sudden sandstorm, a variety known as a haboob in this Sudanese part of the eastern Sahara. Engulfed in a sand front, the light levels plunge and the neutral white balance of what was a bright, sunny afternoon, shifts to red.




         CLOUDY DAWN


         First light over an Andean town, with heavy weather and low clouds contributing to very low light levels (the building lights still dominate).






         Stormy conditions at the summit of a volcano, typical enough in this area in Costa Rica to create a permanent cloud forest.


         Natural light levels are also reduced by shade of one kind or another. Woodland, in particular, furnishes these conditions, especially on a small scale, and when the sky is clear there is likely to be a significant color temperature shift (higher, therefore bluer) as the shade is illuminated by the blue sky. A more common kind of shade is indoors, when the illumination during daylight hours is usually through windows. The age and architectural style of the building, together with the style of interior design, has a controlling influence here, but the major factor is the window area.




         MERLIN’S CAVE


         The legendary Merlin, teacher of King Arthur, is reputed to have lived in this cave, under the Tintagel Castle which is situated on the rugged north coast of Cornwall. The only light source is that from the cave’s entrance, so much of the light falls across the surfaces near there at an extreme angle, with the remainder stemming from a minimal reflection from the dark rocks.


         Outdoors, it is the ends of the day that create the main conditions for low light photography. Light changes quickly in both quantity and quality around sunrise and sunset, and while these two times of day may be indistinguishable to someone viewing the final photograph, they call for different shooting techniques to the middle of the day. The point at which the first and last sunlight of the day becomes a “low light” situation is highly variable, and generally hinges on the usual technical issues of shutter speed and aperture. Generally speaking, when you need to take precautions on camera shake and subject motion blur, you are taking a low light photograph. This depends on choice of subject, focal length of lens, and the depth of the scene, so becomes an issue when shooting away from the sun some time before it is for shots taken into the sun.






         This shot was taken in a well-lit artist’s studio, but to capture it at f/8 nevertheless requires a shutter speed of 1/5 second.






         Friday prayer at the Ansar Mosque in Omdurman. It is lit unevenly through the windows, with the additional complication of a strong paint color that affects the color balance.


         For photography, the two features that dominate this time of day are the sheer variety of lighting angle and the color. With the sun low in the sky, its light rakes horizontal surfaces, hence creating good textures on flat landscapes, and strikes vertical ones, like people and buildings, from one side only. When you factor in the choice of camera viewpoint by moving around a scene, these times of day offer the greatest variety of lighting quality of any. Backlighting, frontal lighting, and all degrees of sidelighting are all there at one time. Above all, this is what makes the ends of the day so useful in photography.


         Color also changes. For most of the day, the color temperature under a direct sun is a fairly constant 5200 K, or rather higher under cloud (up to around 6000 K). When the sun is close to the horizon, at around a 20-degree elevation or less, the color temperature falls, and the light becomes more yellow-to-red. This warm-looking color cast is caused by atmospheric scattering. Particles in the atmosphere scatter the higher energy, shorter wavelengths of sunlight, and as these are in the blue-to-violet end of the spectrum, what is left is more reddish. How red the light is depends on the composition of the atmosphere, as well as the amount of it the sun’s rays are passing through. The sun appears at its reddest when right on the horizon because its rays are traveling through the greatest amount of low-altitude atmosphere. Expect between 3500 K and 4500 K on a fairly clear day.


         Contrary to what many people expect, there is no general distinction in the quality of light between sunrise and sunset. In either case, the sun is low and casts long shadows, and the color temperature is low. However, for every specific location there is a very large difference, and preparations made to shoot differ greatly. The aspect of any major subject obviously matters—which way it faces—and there may be a number of idiosyncratic things to consider. Local weather may change, as in morning mist or late afternoon haze. Activity in a scene is also often different. There also tend to be fewer people around in the early morning, and if this is summer in high to mid latitudes, sunrise is well before most people are even awake. This is a key consideration if you want a view without people or traffic. In other words, to the viewer of a photograph taken with a low sun, there is no way of telling whether it was shot at the beginning or end of the day, other than by being familiar with the actual location. To the photographer, however, the distinction is extremely important for very local reasons.




         ENDS OF THE DAY


         Although they may feel very different, thanks in no small part to the different physical temperatures, the photographic conditions are similar at sunrise and sunset. The ground frost, however, would certainly not be present in the evening.


         Moving beyond the point when the sun is touching the horizon, dawn and dusk create special, shifting conditions that can often deliver lighting surprises. This is marvelous for exploration and also for adding image quality to scenes that might be mundane by day. When the sun is just below the horizon, there is a short period of faded light that may, under the right conditions, offer a different and unusual quality of light to a scene. This is at either end of the day, and the length of twilight is no precise thing. It depends on the latitude and season, and is shortest in the tropics and longest in high latitudes because of the angle at which the sun rises and sets. As a rule, twilight works for photography when the sun is between the horizon (taken as 0) and about 15 degrees below. This is a rather shorter period of time than what most photographers would consider “golden light,” when the sun is a little above the horizon. In any case, the cut-off point between twilight and night is a matter of personal judgment, and can depend on the weather.






         As dusk falls, the artificial lighting starts to compete with the natural light, which serves to add extra interest to this shot.


         If the sky is completely overcast, twilight is irrelevant and indistinguishable—the light simply fades or brightens. If, however, the weather is mainly clear, the color and tonal effects in the sky itself can be very attractive. Twilight without clouds creates a vertical gradation of tone and color as at no other time of the day, and is strongest in appearance in the direction of the light. Depending on the atmospheric conditions, the number of hues in the sky varies. The scale might be from white to indigo, or from red through gray to blue. There is even the possibility of the “green flash,” in which refraction of light in the atmosphere can momentarily color the tip of the sun green.


         The most obvious use to make of twilight is as a backdrop to a silhouetted subject or sky-line, with the sky itself being, in effect, the main subject. In very clear weather, however, there may be enough color from the sky to give a delicate, ethereal illumination to the scene in the opposite direction. Delicate is in any case the keyword here. Good twilight is soft and unpredictable, and the changes in color and intensity tend to happen a lot faster than you notice.


         There is also an important difference in the way that you see a scene as it moves into twilight. The retina has two different systems—photopic vision for bright light, with full color response, and scotopic vision for low light, with more sensitivity to light but poorer color distinction and resolution. The changeover from one to the other takes time. At the end of the day, the scene is getting darker, and the eye and brain take longer to adapt than in the opposite situation, when the scene is getting lighter. This is partly due to familiarity, as fewer people experience daybreak than sunset, but the usual impression as night turns into day is that things are brighter than they really are. If you begin shooting so early in the morning that there is no light in the sky, just before sunrise everything will appear completely bright. Practically, it is important to keep checking the results on the camera’s LCD screen, as your own visual judgment, particularly of color, may not be as reliable as you think. An important caveat here, as already mentioned earlier, is that at this time of day the preview image on the screen can be misleading in brightness. It, of course, stays at a constant brightness while the scene around it is either fading or brightening, so it is very common to underexpose if you go by the screen image alone. At twilight, the screen’s backlighting is much brighter than that of the surroundings, and this exaggerates the brightness of the image as shot, so always check the histogram as well.






         Captured at f/2.8, this dusk scene looks well lit though the chrominance noise is something of a give away.


         Other than pure, natural landscapes, twilight also brings artificial lighting into play. After sunset, street lighting is switched on, as are interior lights in houses and offices, flood-lighting and display lighting. These may or may not be what you expect or want, and will often affect the composition. Lighting in cities tends to be different at each end of the day throughout the year. If you want the maximum amount of interior lighting visible in office blocks, for example, the best time is usually just after sunset in winter, when most people are still working.


         True night photography is when there is not even a trace of residual light from the sun, and this offers a few, limited possibilities (discounting astrophotography, which is a specialization too specific to deal with here). Mainly, night photography is practical when there is a clear moon and the phase is somewhere between half and full. This was both difficult and uncertain in the days of film, but digital technology has now opened this up to non-specialists.






         The moon is 250,000 times dimmer than the sun, but is reflecting the same light.


         The moon, of course, reflects sunlight, so for lighting purposes a full moon behaves like a very dim sun. A figure often quoted, and useful, is 250,000 times dimmer, which is 18 stops as a camera setting. Thus, to revive the “sunny 16” rule mentioned previously, the exposure for a high, full, unclouded moon would be 18 stops less than 1/100 sec at f/16 and ISO 100. This gives about 1 minute at f/2.8. This is a reasonable starting point for an “average” full-moon exposure, meaning within a day or two of perfectly full (0-degree phase angle), within 15 degrees of directly overhead, and in clear air. Unlike film, sensors do not suffer from reciprocity failure, so this exposure needs no further adjustment.




         CITY LIGHTS


         Pudong at night, seen across the Huangpu River from the Bund, Shanghai, China.


         In practice it is very difficult to judge the brightness of moonlight because it varies so much. There are several factors that affect this, and the phase is the most important. Between full and a quarter the brightness varies by an order of magnitude—about 3½ stops. The orbits of the earth around the sun and the moon around the earth also vary, so the sun distance changes by 7 percent and the moon distance by 30 percent, which combines to make a difference of about a third of a stop. The opposition effect, in which there is a sudden increase of brightness when the moon is just almost exactly opposite the sun, caused by the high reflectivity of the moon’s surface, adds another third of a stop of variance. Finally, atmospheric attenuation because of moisture, dust, and the height of the moon above the horizon can make a difference of up to 8 f-stops (over 2 orders of magnitude).






         Moonlight and artificial light create contrasting colors in this image.