CAMERA CHAT.

New Zealand Mail, Issue 1423, 8 June 1899, Page 14

CAMERA CHAT.

riNHOLE PHOTOGRAPH V.

It may probably surprise a great many people who have not given the subject .... special attention to learn that the lens, which seems such an indispensable part of the photographic camera, is in reality as much an accessory as is the glass of the spectacles to the human eye. Such nevertheless, is the case. Excellent photographs can be taken without the intervention of any lens whatever. A few words of explanation here may not be deemed amiss. As every schoolboy * nowadays is aware, the human eye is simply a perfectly constructed camera in miniature. To reproduce theplieuome non of vision on a large scale, all we have to do is to exclude all light from a room except that which is allowed to enter through a small round hole m cue of the sides of the room—in a shutter, for instance. Now look at the wall faeiug the hole in the shutter; you will see a faithful picture of what is going on outside in the street. The only difference is that 'jj the objects are all reversed and unside- ■' down. The human eye and the photographic camera are both simply reduced models of the room with the hole in the shutter; or, rather, it would bo more correct to say, the room with the hole in - the shutter is an enlarged model or the < human eye. Who it was who first investigated the phenomenon of the dark chamber —the ■ camera obseura —is unknown ; though it would appear from recent researches that the honour, like so mauv ether honours, is due to Leonardo a I inci. one of the most universal geniuses that ever lived. At any rate, fifty years after Da Vinci’s death. Porta, a native of Naples, constructed, in the year 1569. a small model of the dark cliainbei. u huh to all intents and purposes is the camera* o or to- — day without the lens. Ever since then it must assuredly have occurred to the mind of many and many a searcher that there might be some means of perpetuating the fleeting pictures that were successively painted on the wall of the camera obseura ; but the secret too it nearly ■ three centuries to discover: otherwise, -■instead of dating from the nineteenth. photography might have dated from me sixteenth century.

Take a thin plate of bright polished silver. Expose it in the dark to the vapour of iodine, until its surface has acquired a light-yellow tint: still keeping all light carefully array from it. place it in a camera—a reduced model of -the room with the hole in tne shutter—opposite the hole. Nov/ uncover the opening; The image of the objects in front of the hole is immediately projected upon the iodine-coated silver plate within die box, and-—remains there; light having the property of chemically modifying the iodine. Such is photography iu its simplest form. The iodine-coated silver plate is nowadays replaced by a highlysensitive dry plate; but the principle remains the same. A lens fixed in the hole

accentuates the action of tlxe light so that the photograph is much more rapidly painted; but just as no spectacles can give as clear a definition as one’s own healthy eye, so does the lens of the camera. distort the images it reflects to a certain extent. In the best lenses this defect has been reduced to the very minimum, but it exists nevertheless, modifying the natural perspective of the pictures. A photograph taken by means of a lens can never be anything, therefore, but an approximately accurate reproduction of a person or scene. The sneer of ■artists at photography is thus justified. Though it has always been recognised that, in principle, a lens was not indispensable, it has hitherto been deemed ’impossible to take a satisfactory photo.graph without it. What are known as .pinhole cameras—that is, cameras which are constructed with a tiny aperture

through which the light is admitted, inr, ‘ fitead of a Tens, have been looked upon more or less as pretty scientific toys demonstrating a principle and nothing more. Photographs, it is true, had been obtained by means of them; but they were always very indistinct—

‘fuzzygraphs/ as they were contemptu- ’ ously called. The unsatisfactory results 5 hitherto obtained are due, it would seem, .entirely to the.fact that the matter had not been properly studied. A French "aTmateur photographer, M. Combe, aftei a series of experiments extending over several years, claims that he has elucidated the most important factors in the problem; and some of the practical results, he has obtained are truly astonishing. " The camera, 1 M. Combe employs was constructed by himself, and, being made out of cardboard, cost only a few pence for materials ; and yet the nhotographs he has succeeded in taking with this simple apparatus are almost perfect and have evoked loud cries of admiration

from all the artists who have seen them. M. Combe shows that the notion hitherto prevalent among such a large number of photographers, that pinhole photography was subject to no laws, is quite erroneous. On the contrary, if successful results are to be achieved by its means, it is absolutely necesary to study and obesrve these laws with the greatest care. The necessary calculations and precautions, however, are not beyond the capacity of any intelligent child. AH that is necessary is to place the sensitive plate at a certain fixed distance from the hole. Knowing the size of the hole, a simple calculation enables the operator in find the precise distance from it at which the plate should be fixed. A difficulty, however, that seemed almost insurmountable was just that of knowing the exact size of the hole. Ii it is easy

enough to measure a hole through which you can push your hand, it is a very different matter to measure one that will not admit a darning-needle. It may measure the hundredth part of an inch across, or it may measure the one-hun-dred and twenty-fifth part of an inch. To know where to fix the plate we must first learn the exact diameter of the hole. How are we to find it out ? or licw are we to make a hole of a given size without invoking the aid of some skilled scientificinstrument maker ?

M. Combe gives us the means, and it does the greatest credit to his ingenuity. He takes a hundred needles, all of the same size and calibre, lays them close together side by side, and measures them across. Suppose lie finds that the hundred needles measure one and a quartei inch. cr. to express the same in decimals. 1.25 inch. To find the diameter cf one needle, ali that is necessary is to divid< I/Jo by ICO —iu other words, to move the decimal point two places tart he.* to the left. .9125. The hole made by such a needle measures, therefore. .0135 inch ; or. in vulgar fractions. 12-1-10.000 of ar. inch; or. simpler still, 1-30 of an inch For every size cf hole there is a corresponding focus at which tire image projected through the hole is at its maxi mum of clearness, and it is at this point at which the plate must always be fixed Photographs taken by this method arc in perfect perspective, and the contours of the objects represented, instead of presenting the hard lines so commonly reproached to photography, possess that soft natural aspect which has hitherto been one of the chief prerogatives of painting. To obtain this quality m theii photographs is precisely what the best operators cf tiie day have been striving to do for a long time past, with more oi less success. The light that can pass through a hole one-iumdecltli part of an inch in diameter is so small in quantity that, .naturally, the plate has to be exposed much longer to its influence than is the case in the ordinary cameras, so that instantaneous photographs of moving objects are unobtainable by pinhole photography. It may well be, however, that some clay photographic plates will be manufactured so sensitive to light that even tlie minute quantity passing through a pinhole will be sufficient to instantly impress them. When that clay comes pinhole photography will perhaps triumph definitely. Meanwhile, after M. Combe's experiments, none need be deterred from being a photographer foi* lack of means to purchase the necessary* apparatus. —"Chambers' Journal.'’