The Optical Magic Lantern Journal (June 1898)

The Optical Magic Lantern Journal and Photographic Enlarger. 97 We will now cut a mask, 83 by 64 inches, with a central aperture of 43 by 31, and then proceed to make prints from the four negatives : unmarked, and then print once more from the first three, using the mask already described. We will then trim down the print with the dark corners until we get rid of these, and shall probably have left a print about 5 by 4. We will now give this print, the two unmasked ones from the two negatives taken with the W.A.R. and the anastigmat and the print from the negative taken with the 10 inch lens probably will be quite satisfied with the first and last, but condemn the second and third on account of their false perspective. “Taken,” he will say, ‘‘ with a wide-angled lens, foreground objects exaggerated in size, distant objects dwarfed, as is always the case when such lenses are used.” We will then show him the three prints made from the negatives, the mask being used, and he will probably say they are quite satisfactory. Thus it will be seen that any so-called exaggerated perspective is due not to the character of the lens employed, but to the way in which it is used. Let us examine the three masked prints and the large one taken with the 10 inch lens, and we shall find that the first three are identically the same, a3 if they had all been printed from the same negative, and that they include exactly the same amount of subject as the large print includes, each object in this last one being exactly twice the height and twice the breadth that it is in any one of the other three. Thus, if the length of the plate bears the same ratio to the focal length of the lens, the pictures will be similar, and by reduction or enlargement may be made to yield prints exactly alike in size and subject included, and the slope of all the lines. Why is it then that the prints taken from the whole of the second and third negatives give an impression of exaggerated perspective? Simply because too wide an angle is included, bringing in objects too near the camera; these are represented in their true proportions by the lens, but offend the eye because, on account of their | exceeding nearness, they occupy too much space. The tombstone close at hand—which would not have been shown at all if the plate included only a moderate angle, and which we cut off by the mask when printing with it on the negative—looks larger than the church itself, and spoils the effect. Thus we find that the wide-angled lens, while it gives a true representation and absolutely correct perspective such as a drawing made by a draughtsman according to the rules of perspective would show, the point of station being the same, yet produces an unpleasant result. The reason that wide-angled lenses have got their bad reputation is because thcy are used improperly. Two men go out armed with cameras of the same size, one with a short focused wide-angled lens, the other with a | long focused narrow-angled one; each phototo some critic, and ask for his opinion. He | graphs the same object so as to get it approximately the same size, and to do this the former has to plant his camera much nearer than the latter, with the result that the lines converge ! much more strongly to the vanishing point, and while the nearer objects may have the same absolute size on the two negatives, the distant ones are much smaller on tnat made with the short focused lens. Ilad they both occupied the same spot when making their exposures, and had the man with the short focused lens been content to use a proportionately smaller | plate so as to include the same angle, both views, though differing in absolute size, would have been equally pleasing. But, it may be asked, why should we usea costly 7 inch W.A.R. or anastigmatic lens, for instance, which is capable of covering a 12 by 10 plate, when only using a 6 by 5 plate in preference to the far cheaper R.R. of the same focus? The reason is that the W.A.R. or anastigmatic doublet, because its component lenses are brought so much nearer together, gives more even illumination, and also because it admits of a much greater use of the rising front when we wish to include a lofty object. If the camera has to be tilted, and the swing back used, it is found that the upper and lower parts of the plate are much out of focus when the centre is correctly focused, and a great deal of stopping down is required ; but the definition over a very large area when an anastigmatic doublet is used is so exquisite that only a very moderate amount of stopping down is needed to secure definition even when the front of the camera is considerably raised, the camera remaining horizontal, and even with one of the older forms of W.A.R.’s less stopping down is needed than when the camera is tilted and the back swung into the vertical plane. Hence, it is our invariable custom to use a lens of one or other of these two last types when engaged in architectural photography.