Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art . 90. Supposing that two lenses of different focal lengths are so placed that a givendimension is equal in the two pictures, what law will govern the size which any otherdimension will have in each? Let us suppose that a poplar tree stands in the centre of the picture, that is, directlybefore the eye, and that another of equal height stands to the right, and further back ;for simplicity let us say that it is as much further back as it is to the right. The linejoin
Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art . 90. Supposing that two lenses of different focal lengths are so placed that a givendimension is equal in the two pictures, what law will govern the size which any otherdimension will have in each? Let us suppose that a poplar tree stands in the centre of the picture, that is, directlybefore the eye, and that another of equal height stands to the right, and further back ;for simplicity let us say that it is as much further back as it is to the right. The linejoining the two will then make an angle of forty-five degrees with the line of sight, that 196 WILSONS QUARTEK CENTURY IN PHOTOGRAPHY. Fig. P subjects, or in view of the Cedars of New Englandwith Mr. R. Swain Gilford (Fig. 196), whose brush hasgiven us so many admirablelessons in composition andcolor. The work of the painterand that of the photogra-pher are largely akin wherethe principles of art areinvolved, only the photog-rapher is expected to tell thetruth, while the painter isnot so apt to be Fig. 197. is, in Fig. 107, A M is equal to M. Also,we can simplify the figure and constructionby supposing that the base of each tree is ona level with the eye. The tree A B has, by condition, the sameheight as A^ B^, but the latter being fartherwill be represented smaller in a perspectivedrawing, and the amount of this reductionis wholly dependent upon the focal length of the Let us take to represent the focallength of any lens. Then determine thevanishing-point of the line connecting thetwo trees by drawing F V parallel to A A\the intersection of i^Fwith the line A V\perpendicular to the line of sighti^^, viz.:V will be the vanishing-point. Draw theline B F, and connect with At the point C where this last line cuts A F erect aperpendicular till it intersects FB^. Thelength, CZ>, of this perpendicular will be thecomparative height which the distant treewill have, as depic
Size: 2152px × 1161px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookidwilsonsquart, bookyear1887
