SU686002A1 - Method and apparatus for aerial photography - Google Patents

Description

I

This invention relates to aerial photography methods that provide for photographing under conditions of reduced ambient light, for example, during aerial photography at night.

There is a known method of aerial photography under conditions of reduced illumination of the terrain, the essence of which is the illumination of the photographed terrain using pyrotechnic or electric light sources ij.

However, this method does not provide high-quality photographs.

There is a known method of aerial photography by double exposure of a film, the first of which is carried out with a short exposure from the source of preliminary illumination, and the second from the object of photographing 2.

However, during aerial photography under low light conditions, a slight removal of the means of illumination from the photographic object causes uneven distribution of light over the photograph.

terrain, which causes uneven illumination across the field of the frame and reduces the quality of the aerial image.

The aim of the invention is to align the optical density with the frame field.

This is achieved by the fact that according to the proposed method, the first exposure is carried out in a frame window by a light flux of variable optical density.

The proposed method is implemented with a device containing an airborne camera with a lens, a shutter and a photographic film. The difference in the device lies in the fact that the pre-light source located around the lens and the light filter of variable optical density, installed between the pre-light source and the film, are additionally introduced.

Claims (2)

FIG. 1 shows a diagram of an apparatus for implementing the proposed method; Fig. 2 shows versions of a pre-exposure source. The device contains photographic film 1, leveling table 2, frame frame 3, frame window 4, body 5 of an aerial camera, lens with a diaphragm and photo shutter 6, low-power source 7 of preliminary film illumination before exposure, light scattering screen 8 of variable optical density with a hole for the lens. The small source 7 is located around the lens 6 with its circumference around the perimeter and directed towards the focal plane. In the embodiment (a), the source 7 is made in the form of an annular low-power photo-illuminating flash lamp, for example, an IFB-ZOO type. In the variant of use (b), the source 7 is made in the form of several photo-illuminating pulsed lamps. For example, type IFC-5. The design (b) of the embodiment of FIG. 1 is more flexible both in the placement of the lamps around the lens 6 and in creating the required illumination in the plane of the frame. The source 7 is closed by a diffractive optical density screen 8. The screen 8, together with the source 7, creates in the focal plane the distribution of illumination ps to the frame field of the frame opposite to the illumination from the means of illumination of the photographic object. Constructively, the screen 8 is a light-diffusing plate of variable optical density with an increase in the transparency to the edges of the plate. The highest optical density (continuity) of screen 8 should be in the center. This part of the screen 8 is removed under the airfoil for lens 6, Screen 8 as detected by the nozzle on the last lens line. The proposed method is implemented as follows. An airplane with an aerial camera and a mid-level terrain is moving over the terrain being photographed. The photographic film 1, pressed from the side of the substrate to the leveling table 2 by means of a vacuum suction device, moves IB in the direction of the film to compensate for the image shift from the translational motion of the aircraft. The shutter of the aerial camera is closed. Immediately prior to exposure of the terrain ivi, the source 7 with a short shutter speed pre-illuminates the film 1 in the frame window 4 through a light scattering screen of variable optical density 8 with the lens shutter closed. 6. 6 2 Then the inter lens cover of lens 6 opens and closes after the flash of light from the means of illumination of the photographed area. On a pre-illuminated frame, lens 6 during illumination of the area by means of illumination builds an image of the object of photographing. At the same time, source 7 is disabled. The imaging of the photographic object takes place in a frame on film 1 with a targeted change (increase) in the photosensitivity along the frame field to align the optical density of the future image. After the shutter is closed, the rewind is accelerated from. the shot is taken and the cycle of photographing is repeated. Thus, the proposed technical solution allows the use of double exposure for the purpose of aligning the optical density of the image with the field of the frame while increasing the overall photosensitivity of the film, as well as the associated possibility of extending the range of photographing by working with shorter exposures at the main exposure, reducing power the source of the object is photographed and. Claim 1. Airborne photography by double exposure of film, the first of which is carried out with a short exposure to the source of pre-exposure, and the second - from the object of photographing, characterized in that, in order to align the optical density across the frame field, the first exposure took in a frame window with a light flux of variable optical density, 2. A device for carrying out the aerial photography method according to claim 1, comprising an aerial camera with a lens, a shutter and a photographic film characterized in then it is further introduced provisional illumination source disposed around the lens, and the variable optical density filter positioned between the source and the pre-exposure of film. Sources of information taken into account in the examination 1. Alekseev V.I. dr. Intelligence and lighting equipment of aircraft. VVIA tl. Zhukovsky, Part 1, 422. Ed. 686002 2. A. A. Kartuzhansky. Physical s, 421 bases of the photographic process, Art, 1965, p. 65-75 {prototype). S MgTzGPGG G fii fllf Jljfrf f