Airships past and present, together with chapters on the use of balloons in connection with meteorology, photography and the carrier pigeon . ickly aspossible. The camera has one lens andonly one plate is used, a third of it beiugexposed behind the three filters in succes-sion. The wrhole thing is done auto-matically by pressing a rubber ball, andthis changes the filters and the portion ofthe plate which is exposed. Colourphotography is made very simple in a balloon by the factthat the three exposures can be made simultaneously, by usingthree lenses, one beside the other, the distance of the o
Airships past and present, together with chapters on the use of balloons in connection with meteorology, photography and the carrier pigeon . ickly aspossible. The camera has one lens andonly one plate is used, a third of it beiugexposed behind the three filters in succes-sion. The wrhole thing is done auto-matically by pressing a rubber ball, andthis changes the filters and the portion ofthe plate which is exposed. Colourphotography is made very simple in a balloon by the factthat the three exposures can be made simultaneously, by usingthree lenses, one beside the other, the distance of the objectbeing so great that no trouble arises from parallax. If thethree lenses are mounted so that their axes are at distances ofabout 3 in., and their focal lengths are from 6J to 7 in., no dis-placement of the image due to parallax can be noticed if theballoon is 800 ft. above the ground level. Professor Miethes camera therefore consists of a solidlyconstructed box, containing the whole of the apparatus, thefront of which contains the three lenses, side by side, and hasslight projections fitted to it in order to protect the lenses from. FIG. 211. — Camera forthree-colour photogra-phy. L THE I-NTEKPBETATION OF PHOTOGEAPHS. 838 any accidental injury that might be caused by jolts or inside of the box is divided into three compartments, corre-sponding to the three lenses. The plate is 8J by 9% in., and issimilarly divided into three parts. The focal length of the lensis about V)] in., and works with an aperture of F/45. Threecarriers are provided for the filters, which are placed immediatelyin front of the plate. The camera has no focussing screen,seeing that it is adjusted once for all. A shutter of the slit typeis used, and at the back there are the usual double-backs. Thewhole of the manipulation is done from the outside, and thedouble-backs are fitted with rolling blinds. Isochromatic platesmust be used, and they must be sufficiently sensitive to red lightto take a
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Keywords: ., bookcentury1900, bookdecade1900, bookpubl, booksubjectaeronautics
