There is another class of lenses of double combination, which are called wide angle lenses. They are constructed to embrace an angle of from 90 to 100 degrees, and are therefore indispensable for use in confined situations, such as narrow streets and interiors. They are also capable of being used with advantage for all the purposes of a view-lens, their only disadvantage being that they are not so rapid as lenses of a lesser angle. For certain subjects the back lens of the combination may be removed and the front lens used in the same manner as an ordinary landscape lens.
The E. A. Wide Angle-Lens is of this class, and being of short focus and made on the rectilinear principle, it is a useful lens for all the purposes already enumerated, and for architectural subjects, as well as for copying of maps, drawings, printed matter, etc., etc.
Every amateur should possess one of these lenses, as well as one of the more rapid-acting lenses for instantaneous work, unless he can well afford to get the best.
Dallmeyer's Wide-Angle Rectilinear Lens.
Dallmeyer's Wide-Angle Rectilinear Lens will completely fill the bill. This lens consists of two cemented combinations, each composed of a deep meniscus crown and a deep concavo-convex flint glass lens.
Unlike other lenses of this class the dense refracting medium - the flint - is made to occupy the external position in both combinations, and though both are deep menisci externally, and of nearly the same focal lengths, the front combination is of larger diameter and greater curvature than the back, and between the two, dividing the space in the proportion of their respective diameters, is placed the revolving diaphragm, with graduated openings, the largest of which is F. 15.
An important characteristic of this instrument, besides the method of achromatization, is the thinness of the lenses, thus offering less obstruction to the passage of the light, constituting these lenses the quickest acting of their kind.
The outfit, which includes a Dallmeyer wide angle and a Dallmeyer rapid rectilinear, may be said to be prepared to do all work within the range of photography.
Every outfit should include a piece of fine, soft chamois skin for cleaning the lenses; it will often be found that moisture and dust obscure the image in the ground glass; when such is the case the lenses should be unscrewed and carefully cleaned with the chamois. And when carrying, it would be well to wrap each lens in a piece of chamois. Lenses thus carefully kept will repay the trouble in line, clear and incisive work.
Fig. 2. The Tripod Or Camera Stand.
There are a variety of these stands manufactured, the two principal of which are the Telescopic leg, Fig. 1, and the Folding leg, Fig. 2. Among the lighter stands or tripods deserves particular mention, being less than two pounds (2 lbs.) in weight and folding to a length of 16 inches only. When placed in its neat leather case, with shoulder-straps for carrying, it is the smallest and lightest practical tripod that has yet been offered to the public.
The Fairy Tripod.
The tripod, when not in use, is taken apart, the top placed in the carrying box, and the legs folded cr telescoped and tied together.
When set up for work be sure to have the tripod top level, which may easily be done by adjusting the legs to the inequalities of the ground.
The Camera is fastened to the tripod top by a thumbscrew, which passes up from beneath, through the tripod top, and into the leg of the box. When adjusted tighten the screw firmly.