The student must be careful to see that the inside of the camera is a dead black, and that it keeps so. At times the camera may leak or get out of register, that is, the plate does not exactly take the place of the ground glass, in which case he should at once send it to the maker. |Test for register.| Should the student wish at any time to test the register of his camera, he has only to pin up a printed card and focus it as sharply as possible, using a magnifying glass, if one is at hand. Then load the dark-slide with a plate of ground-glass, and after sliding it into position, open the slide (if a double-back) when the image will be seen on the ground-glass plate, and its sharpness can be noted. If perfectly sharp, the camera is in register.
Hand cameras.
A good form of small camera to be carried in the hand is a great desideratum for artistic studies. Exquisite studies of figures, birds, and all sorts of animal life could be made with such a contrivance, studies admirably suitable for tail-pieces or illustrations to go in with the text. That there are dozens of patterns of hand cameras commonly called “detective cameras,” we are well aware, and we have tried some of the best, but we have found none satisfactory for artistic purposes, and can therefore recommend none. We may here remark that the name “detective camera” is, in our opinion, undesirable, photographers ought not to have it even suggested to them that they are doing mean, spying work with their cameras, whereas the term “hand camera” meets every requirement. Of course the smaller cameras advertised to be worn on the person are nothing but toys. The camera we should like to see introduced would be a very light collapsible camera, which could be easily carried in the pocket when not in use. It should be able to take pictures not larger than four and a half by three and a half inches, and should be fitted with the Eastman spools, so that any number of exposures could be made. The lens should be Dallmeyer’s long focus rectilinear landscape lens, fitted with a good shutter. There should be a light view meter attached to the top. There is no necessity for a ground-glass screen, for on the tail-board could be registered various distances, at which the film is in focus; and since for artistic purposes most of the studies would be of objects near at hand, this arrangement would be effectual.
View finder.
Many hand cameras are fitted with a camera obscura. The handiest view finder for quick exposure work is to fit a double convex lens of the same focal length as the working lens to the front of the camera, and turn up the focussing screen at right angles to the plane of the top of the camera, when it may be secured by a small brass catch fitted for the purpose. When the focussing cloth is thrown over the lens and screen a temporary double camera is made, and the moving objects can be watched on the ground glass. With experience it is possible to judge by simply looking over the top of the camera.
CHAPTER II.
LENSES.
Optics.
We do not intend to incorporate in this chapter elementary optics, as the subject is well known to most educated men, but in case any reader should know nothing of light and optics, we recommend him to get |Ganot’s Physics.|Ganot’s Physics, and thoroughly master at least the paragraphs of Book VII., on “Light,” that we enumerate below.[[10]] This may seem a little formidable, but our reader will find that with a very simple knowledge of mathematics he can easily understand all the sections marked, and it is our opinion that light and chemistry should be studied directly from systematic text-books that treat of those subjects. In the Appendix we shall refer to some additional books which we consider advisable for the student to read, but for the present we strongly recommend him to thoroughly master the parts of Ganot that we have cited, and to avoid all other desultory reading until he has done so.
[10]. Namely, paragraphs 499, 500, 501, 502, 503, 504, 506, 508—the Laws of the Intensity of Light, 509—Photometers, Rumford’s and Bunsen’s, 510, 511—first proof only, 512, 513, 514, 518, 519, 524, 525, 528, 533, 536, 537, 538, 539, 540, 542, 543, 544, 551, 552, 554, 555, 556, 558, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 579, 580, 581, 582, 583, 584, 602, 604, 612, 615, 616, 617, 618, 619, 620, 621, 625, 626, 627, 628, 629, 631, 632, 634, 635, 636, 637, 639, 640, 641, 645, 646, 650, 652, 655, 656, 659, 661, and 664.