Find out how natural light affects your shots, how daylight is made up of sunlight and diffuse light and how the color temperature changes depending on the location and conditions. The text describes the characteristics of sunlight, moonlight and artificial light and the challenges of taking pictures under these conditions.
Daylight consists of directly incident sunlight and light scattered in the atmosphere, skylight. The mixture of both components determines the color of illumination which varies depending on time of day and the time of year from 4800 K - 18 000 K.
By using conversion filters, the composition of light can be changed in such a way that a sensor which is exactly balanced at 5500 K renders natural colors. The decision which filter to take in each case is however not as difficult as is generally thought. The two most important criteria are altitude of location and the color of the sky. As altitude increases above sea-level, the proportion of short-wave blue radiation in illumination increases also. It has to be balanced by a reddish filter. In areas where the air is pure, that is, far away from urban centres and industrial plant, illumination follows this tendency. As the atmosphere becomes more clouded, the color temperature of radiation falls, illumination is seen as reddish by the film. Industrial and city haze has the greatest effect on light composition even with a clear-blue sky. With a great amount of haze, when the sky is from dull blue to yellowish white, a light blue KB 1.5 correction filter should be used. A point of reference for determining illumination is if there are clouds present. If there are few clouds, clearly outlined against a blue sky, a reddish conversation filter is abvisable. If clouds cover more than half the area of sky, a colorless UV haze filter is more to advantage. If the clouds are hardly visible in the haze, noticeably reducing sunlight and preventing the creation of sharp shadow, then it is clear that a light blue filter is required.
The sun radiates at a color temperature of 5800 K. As observers, we always have the impression that sunlight is yellow or gold. It is more like the flame from an electric welder. The eye is fooled; influenced by the blue of the sky surrounding the sun, the eye assigns the sun a warmer tone than it really has, since it does not have the ability to measure exactly. On the other hand, the eye is superb at comparison, and can adapt to every color temperature which film cannot do.
On its way through the atmosphere, the radiation of the sun is altered in many ways. Ultraviolet radiation below 180 nm cannot penetrate the atmosphere at all. In the infrared range, radiation is weakened by water vapor and absorbed to a greater or less extent depending on wavelength. But the most important change sunlight undergoes is caused by the molecules of the air, see Skylight. A direct shot of the sun is possible using very high density gray filters which only transmit a ten thousandth of incident light.
durchlassen.
This light is reflected sunlight striking the moon's surface. It has a color temperature of approximately 4000 K and therefore has a warmer color tone than sunlight.
However, at full moon, illumination is so weak that the exposure time is 100,000 times as long as for a sunny summer landscape. For color shots, there is the extra difficulty of achieving the correct color rendition. Color illumination and the sensitivity of the eye do not agree at all for night or dusk vision. Sensor "sees" red, the eye sees blue.
Please do not hesitate to contact us if you have any questions. Our dedicated team is here to help you every step of the way. Whether you need assistance with product selection, technical specifications, or general inquiries.
Jos. Schneider Optische Werke GmbH
Ringstraße 132
55543 Bad Kreuznach | Germany
Tel: +49 (0) 671 601 205
isales(at)schneiderkreuznach.com
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