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 p162 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 fine, clear and incisive work.
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 p163 THE FAIRY TRIPOD 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 or telescoped and tied together.