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Posts Tagged ‘light source’

postheadericon Composing Photo with Street Lights

Downtown street lighting and display lighting continues to get brighter and more colorful around the world, and is perfect material for digital shooting. The light sources available outside at night are the same types as those that we have just looked at, but in different proportions. Vapor lamps are used much more extensively outdoors than indoors, because of their higher output; this is particularly true of street lighting and floodlighting. Tungsten as street lighting is increasingly less common, but can be seen in shop and other windows, and as car lights. Overall, entertainment and shopping districts in cities are getting brighter and more interesting.

Although the light sources are the same as those used to illuminate interiors, their effect is very different. The scale of the usual type of outdoor shot is greater, and the surroundings do not give the same degree of reflection as do interior walls and ceilings. As a result, there is much more pooling of light: in a typical scene there are any lights, and they are localized. Only very rarely are there enough lights in a concentrated area to give the impression of overall illumination. This happens, for instance, in the busiest part of a downtown night-club district; at some open-air night-markets; and, as you might expect, in sports stadiums. A general solution to this is to shoot at dusk, when there is just a little residual daylight.

In most night-time city views, however, there is either one well-lit area, such as a floodlit building, or a pattern of small lights. In many ways, this type of light causes fewer difficulties than an interior, and there are fewer occasions when you might need to decide on the principal light source and correct the color. The impression of a color cas occurs when most of the picture area is affected; when there are other lights in the image, color balance becomes a much less important consideration.

The localization of the light sources makes measurement difficult. Use it as a guide rather than as a completely accurate recommendation, and bracket exposures around the figures given. For many night-time scenes, the accuracy of the exposure is not, in fact, very critical. Overexposure often does little harm, as it opens up the shadow areas in a scene. The best answer is to experiment, which is of course what digital cameras allow.

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postheadericon Complicated Mixed Lighting

When interiors combine different kinds of lighting, you can expect a clash of colors, but for shooting you will have to choose one white balance setting that makes the best of the situation. One trend in lighting interiors, particularly large spaces, is to mix light sources from incandescent, fluorescent, and vapor discharge lights. Again, the issue to address in photography is the gap between what the eye sees and what the sensor records. Mixed lighting works because our eyes accommodate to color changes so easily, but the camera’s response will nearly always show up the differences within the same scene. Depending on how the lamps are situated, they may combine to give a blend of color, or they may cast separate pools of differently colored light.

Once again, digital cameras come to the rescue in a way that was impossible with film photography. Not only is the color response of the sensor less extreme that that of film, but you have the advantage of instant feedback from the LCD display. The positive side of mixed lighting is that the color combinations can be intrinsically attractive and contribute to the image. Then again, the unattractive associations of green light may be exactly what you need if you intend to convey a particular kind of atmosphere.

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postheadericon Vapor Discharge Lighting, How to Deal

Digital capture comes to the rescue in what have traditionally been some of the nastiest lighting situations in photography-greens, blues, and yellows from vapor lamps that often look deceptively white. Vapor discharge lighting is definitely on the increase, particularly in public spaces, department stores and shops, and is gradually taking over from fluorescent and tungsten lighting. Being more powerful than either of these two, vapor lamps are good for lighting large spaces brightly, both outside and inside. What they are not good for, unfortunately, is photography. The problem is that, for the most part, they look white to the eye-which is why they are popular-but in photographs they usually cast a strongly colored light over the scene. Worse still, they are not consistent or predictable.

The three principal types of lamp are sodium, which looks yellow in photographs; mercury, which looks like a cold white and photographs between green and blue-green; and multi-vapor, which also looks cold white but may, if you are lucky, appear reasonably well balanced in a photograph. Sodium lamps are typically used for street-lighting and for floodlighting buildings; multi-vapor lamps are used in sports stadiums where television cameras need good color balance; and mercury lamps are used in lots of different situations. Sodium is easy to spot-it looks yellow and, when just switched on, glows orange for a few minutes. The other two easily fool the eye, although when mercury lamps are switched on, they glow greenish before they reach full strength.

The reason for the problem is that the emissions of vapor discharge lamps peak strongly in very narrow bands of spectrum, and are completely lacking in many wavelengths. Unlike fluorescent tubes, they do not have the benefit of a coating of fluorescers to spread the output over other parts of the spectrum. With film this made for a truly difficult situation, but digital cameras score in two ways: the normal response of the sensor to vapor lamps is less extreme than with color film, and the white-balance menu allows you to reach a neutral color balance-or something close to it at least.

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postheadericon Fluorescent Light Shots

One of the most common types of indoor lighting, fluorescent lamps look white but photographed green, and call for white balance correction. Fluorescent lamps have a discontinuous spectrum and produce, usually, a greenish color cast. They work by means of an electric discharge passed through vapor sealed in a glass tube, with a fluorescent coating on the inside of the glass. Theses fluorescers glow at different wavelengths, and have the effect of spreading the spectrum of the lamp’s light. Visually this works very well and the eye registers the light as white, if a little cold. However, in photography, this colors the scene unattractively.

If these deficiencies were consistent, it would be a simple matter of using one standard white balance correction. However,fluorescent lamps vary in the visual effect that the manufacturer tries to produce. Some are only slightly green when photographed; others are very green. All digital cameras have at least one white balance correction setting, but some feature a choice, with, for instance, separate settings for “Daylight”, “Warm White,” and “Cool White” lamps. It is difficult to tell just by looking now how much of a green cast will appear. It is usually best to test it by shooting with the basic white balance setting and then adjusting from there.

A large part of the problem, aesthetically, is that an overall bias towards green is considered unattractive by most people, except in special and occasional circumstances. A shift to orange is generally tolerated but the same is not true of green. Whereas orange is a color of illumination that is within our visual experience (e.g. firelight, rich sunsets) and has, on the whole, pleasant associations of warmth, green is not a natural color of light. Although this is a fairly good reason for wanting to make corrections, you should, as a first step, think about whether you can make some use of the green cast, or indeed whether the color will make any important detrimental difference to the image.

UPDATED! Green Screen Wizard Full Version 7.0 offers the latest in green and BLUE screen software power and control behind an amazingly simple and accessible user interface. This chroma key software provides professional photographers, as well as photography enthusiasts, a simple way to do green screen removal and substitutes their choice of digital background. Green Screen Wizard is a self-contained chroma key removal program that does not require Photoshop or other photo editing application to produce beautiful green screen photos. Learn more now and try a free demo version!

postheadericon Light Sources – Photography

Among the variety of light sources used in photography, the artificial lighting found in houses, offices, city streets, and public spaces is often considered to be the poor relation. Daylight is purpose-built and so designed for camera and lens settings that are close to ideal. What remains, generally known as available, ambient, or existing lighting, can be problematic, but may also be interesting.

 

Available light used to be at best a challenge, with a great deal of built-in uncertainty. Available light levels are lower than ideal for use with film, so one of the issues was whether to sacrifice detail by opting for a faster and so grainier emulsion, or accept some movement blue by staying wit a fine-grained emulsion and using a tripod for steadiness. Another issue was color balance, involving first a choice of daylight or tungsten film, and second a choice of filter. This was on top of having a method of judging the color of the lighting; namely  a color meter, experience, or guesswork.

 

Digital photography does away with all of this at a stroke, and available light becomes a pleasure – or at least an arena of lighting situations that is almost as easy on the camera as it is on the eye. This has some very important practical effects, on time and cost. There is almost no need for advance planning and calculation. You can decide in an instant what the color balance is likely to be then choose the appropriate white balance and check the result. If it is not quite right, you can go back to the menu and adjust it. It should take no more than a minute to reach a passable color balance in even the most difficult conditions.

 

And then there is the issue of cost, which affects the number of different shots that photographers attempt. Available light is often patchy, with the light sources themselves frequently in shot, and this encourages bracketing and different filter combinations just to be safe. Or rather, it used to encourage this, but now the immediate view on the LCD screen shows you what adjustments to make. No longer do you need filters, or backup rolls of tungsten and high-speed film, or a second camera body for them. A single digital camera has it all, and this surely takes the pain out of available-light photography.

<UPDATED! Green Screen Wizard Full Version 7.0 offers the latest in green and BLUE screen software power and control behind an amazingly simple and accessible user interface. This chroma key software provides professional photographers, as well as photography enthusiasts, a simple way to do green screen removal and substitutes their choice of digital background. Green Screen Wizard is a self-contained chroma key removal program that does not require Photoshop or other photo editing application to produce beautiful green screen photos. Learn more now and try a free demo version!

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