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556 THE PHOTOGRAPHIC NEWS. [August 7, 1891. PHOTOGRAPHING LANDSCAPES BY MOONLIGHT. The many fabulous stories told about moonlight photo graphs, the incredulously short time of exposure occasion ally alleged as sufficient to make them, a few very remark able facts having come lately to our knowledge, and the desire of several of our readers to learn of the experience of others regarding moonlight photography, have induced us to explain, to the best of our ability, what the light of our satellite is really able to do photographically, and what it is unable to do. Owing to the extremely feeble actinic force of moon light it is impossible to obtain instantaneous views by its aid, and a fully exposed negative can be obtained only by large apertures of lenses of great luminous power, and by long exposure upon highly sensitive plates. To make pictures by the aid of moonlight is nothing new, the first experiments made dating back to the earliest times of Daguerreotypy, and the first moonlit picture exhibited publicly was a white marble bust by Breeze, at the London Exhibition of 1851. On account of technical difficulties resulting from long exposures on wet collodion plates, the attempts made then were but rarely successful, and only after the introduction of collodion dry plates were more satisfactory moonlight pictures really possible. The first moonlight photograph we ever attempted was that of a white painted frame house, with an exposure of three hours upon a Sutton collodion honey plate, with an 8-inch focus single achromatic lens, stop f/16. Result: a very faint image after a long and tedious development with pyro. Later, much better success was had with a view of a brick house, a Fothergill plate, the same objec tive and stop as before, and an exposure of from 8 p.m., perhaps, to 5.30 a.m., in the light of the full moon of a bright November night. Burton states positively that to photograph a landscape illuminated by moonlight requires from 300,000 to 3,000,000 times longer than the same landscape illuminated by sunlight. E. Von Gotthardt indorses what Burton says, and speaks of these facts more definitely when describing some experiments he made. To convince himself of the impossibility of certain claims, he exposed first highly sensitive orthochromatic plates, with a No. 1 Euryscope full aperture for three and five minutes, upon a moonlit landscape, without any result, and forty-five minutes produced a very much under-exposed negative ; double, and more than double the time presumably being required to make a perfect negative. The experiments were repeated in full sunlight, the lens stopped down to its smallest aperture, and, all other conditions being the same, a beautiful and perfect negative resulted from an exposure as quick as could be made by hand. Von Gotthardt now reasons thus: Supposing the sunlight exposure had been 0-5 of a second, and the stop used had allowed but z, part of the light to act which acts with the full aperture, and further supposing that 100 minutes=6,000 seconds in moonlight, would give with the full aperture the same results as obtained in sun light, that is with the smallest stop in 144,000 seconds, we must then deduce that sunlight is 144,000 x 2=288,000, or in round numbers 300,000 times more intense than moonlight. Eder speaks of an experiment by which he found the intensity of moonlight to be 6,000 times weaker than that of a magnesium wire burnt in the focus of a concave mirror, and states further that he had made a moonlight landscape by an exposure of three hours upon a plate 20 deg. Warnerke, with a Steinheil aplanate, stop f/10. Henderson, under conditions similar to those of Eder, exposed for seven hours, and Jahr had perfect negatives in eight and nine hours. Dunmore obtained a very rich and harmonious moon light landscape in five hours, and it is said that Colard and Holmer had the same results in from one to two hours, while Causson and Co. exposed for thirty minutes with the full aperture of a portrait lens. The great difference of the times of exposure stated is owing mainly to the different forms of the objectives employed and their focal length, but is not at all contradictory to the principle laid down by Von Gotthardt. Causson and Co. used a portrait lens, and Jahr a Dallmeyer rectilinear, both with perfect success, it is said. Our latest attempt to make a moonlight picture was by the full moon of last August, the object being a white building surrounded by trees at a distance of about two hundred yards. The plate, a Carbutt Eclipse, the lens a Gundlach rapid rectigraph No. 3, stop f/11. A heavy bank of clouds coming up the horizon interrupted the exposure, intended to be seven hours, and but ninety minutes were given. A tedious and long-continued deve lopment with hydrochinon produced the outline of the landscape, and but a feeble impression of the white building. For scientific purposes, and as a technical object lesson to the photographer, the attempts at making pictures by moonlight are very instructive perhaps, and are otherwise interesting ; but artistically they do not amount to much. Light and shade are not distinctly defined, as the motion of the moon obliterates all artistic effect in the prolonged exposure, and the finished picture reminds one of the works of Chinese artists, totally devoid of details, as well as of light and shade. Moonlight photographs with distinctly pronounced shadows are impossible, and those claiming to be so are invariably made by daylight produced by a variety of clever printing and other dodges, and may be very beautiful so far as the moonlight effect is concerned. —The Photo graphic Timts. Mr. TYLAR, of Birmingham, seems to have an inexhaustible faculty for devising clever contrivances for the comfort of photographers. His most recent one is a very cheap single dark slide, stamped out of one piece of metal, and neatly re versed to hold the plate or film. The shutter, also of metal, draws right out, and the movement can be executed without any chance of stray light finding its way where it is not wanted. A New Platinum and Gold Tonino Bath.—A well known amateur, the Rev. H. B. Hare, has suggested the use of the ordinary gold and borax toning bath, and then a platinum bath for ordinary albumen prints. The prints are just wetted, then immersed in the ordinary borax bath A :— A.—Chloride of gold ... ... ... 2 grains Borax ... ... ... ... 90 ,, Water ... ... ... ... 12 ounces The prints are allowed to remain in this till they assume a warm brown colour, are then removed and placed for a minute in clean water, and then placed in the platinum bath B - B.—Chloroplatinite of potassium ... 24 grains Citric acid ... ... ... ... 60 ,, Salt 96 „ Water 12 ounces When they quickly assume a fine purple black.
