DOFMaster
for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases. |
get a pure infrared photograph. become evident in aerial photos even when the pictures are made on "clear" days. Haze has the effect of r e f l e c t i n g a n d s c a t t e r i n g t h e s h o r t e r wavelengths--ultraviolet radiation and blue light. Since all films are sensitive to these shorter wavelengths, they record as a veil over the scene when more pronounced as the altitude of the aircraft is vapor and dust particles) between the aircraft and the ground increases. Filters used for controlling haze in aerial work range in color from light yellow to red. When you use these filters, the photographic image is recorded by light with a longer wavelength (green or red) that is not appreciably scattered by haze. Filters, such as Kodak Wratten No. 2B or 2E, absorb ultraviolet radiation and reduce the effects of haze without affecting the monochromatic rendering of visible colors. When greater haze control for black-and-white photography is required, deeper yellow or red filters should be used. However, when these deeper colored filters are used, the tonal rendering of colors is affected. The amount of haze control in black-and-white aerial photography increases with the use of the following filters in this order: No. 8 (yellow), No. 15 (deep yellow), and No. 25 (red). The greatest penetration or control of haze for black-and-white aerial photography can be obtained by using a black-and-white infrared sensitive film with a suitable filter, such as a No. 25, No. 29, No. 70, or No. 89B. because all colors of light must be used to obtain correct (true color) results. Filters used with color film are usually colorless or pale pink, such as a No. 1A Skylight filter, or one of several densities of pale yellow (No, 2B and 2E, for example). These filters are not dense days when haze is minimal and you are taking verticals or low obliques from altitudes below 2,000 feet, good color results may be obtained without using a filter. However, when haze is apparent or when you are taking high obliques, the use of a UV16, or 1A Skylight filter is a problem, consider using a No. 2B and No. 2E filter. with each package of film. penetration filters have no effect on mist or fog. Atmospheric haze is always present, but it is especially noticeable in distant scenes and from high altitudes. exposure for ground photography. You can make exposure readings with your meter before leaving the ground to determine the proper exposure for ground photography. (Be sure to allow for the filter factor correction.) In most cases, for low level air-to-ground photography and for air-to-air photography, you should use about the same exposure in the air as you would use on the ground. Once you are airborne and before taking ground from about the same altitude that you plan to work When you are at a fairly low altitude with little or no visible haze, the exposure reading should be very similar to the ground exposure. So set the camera about halfway between the two readings. However, if you airborne meter reading may be significantly higher than the ground reading. This is because your meter is affected by the large area of sky and the amount of light reflected by the haze. In this situation, the camera setting should be determined by the substitution method. a suitable substitute may be used to determine basic exposure. In any event, bracket your exposure by at least one f/stop whenever possible. It is more economical to take a wide range of exposures than to refly a mission. High altitudes, the sky in high obliques, and high levels of haze reduce subject contrast and increase exposure latitude. These factors oftentimes cause overexposure. objectionable image motion. Set the focus at infinity, and set the aperture wide open. There is no need to stop Advanced Photography Course |
As an Amazon Associate I earn from qualifying purchases. |
WWW.DOFMASTER.COM
© 2006 Don Fleming. All rights reserved. |