Photography in the Studio and in the Field / A Practical Manual Designed as a Companion Alike to the Professional and the Amateur Photographer

by Edward M. Estabrooke

The combinations of lenses are three, the single, double and triple; the latter is now no longer in use, or if so, its use is greatly restricted. The single combinations have greater focal length than the double, and consequently at the same diameters larger pictures are obtainable, and they are principally used for landscape or view work.

The double combinations, so called from having a second pair of lenses behind the first, which have the effect of shortening the focus about one-half, whereby the action of the light is accelerated, and both the spherical and chromatic aberrations more perfectly corrected, which result in an image more delicate in definition and more rotund in form, thus peculiarly qualifying them as portrait lenses.

In the selection of lenses for studio or view work, the intending purchaser, if desirous and pecuniarily able to avail himself of the best, will naturally inquire what make of lenses is the most widely known and used, and it will not take much time to procure a satisfactory answer to the question.

It has been conceded now for some years, both in Europe and in America, that the lenses manufactured by J. H. Dallmeyer, of London, England, are superior to all others, not only for their fitness for the work for which they are specially constructed, but for their adaptability to work beyond anything claimed for them by the maker, and also for a certain undefinable and æsthetic quality inherent in the negative made by these lenses.

The fact that there is not in the wide world a photographic p92 establishment of any note that does not possess one or more of these lenses is strong evidence of their superiority. In the quality of the glass used, in the perfection of finish and adjustment, in softness, crispness and depth, in rapidity, illumination and every quality that recommends a lens, the Dallmeyer lenses are unrivalled.

FIG. 6.

The portrait combination now in general use, was first constructed from calculations made by Professor Petzval, of Vienna. Its optical components are, a front crown lens of unequal convex curves to which is cemented a double flint lens of unequal concave curves. The back combination is a crown lens of unequal convex curves and a concavo-convex flint lens at a little space from it. (See Fig. 6.)

For more than a quarter of a century this form of lens had been used without material change in its construction, until Mr. Thos. Ross, by a modification of the curves, succeeded in flattening the field and increased its rapidity by shortening the focus, but left it with the peculiar shallowness of focal depth, especially in the larger sizes, which has been the torment of photographers to this time.

Mr. Dallmeyer was the first to improve upon the p93 original portrait combination, and in his new Patent Portrait Lens he has most ingeniously obtained a diffusion of focus at the will of the operator. By a quarter or half turn of the cell of the back combination the focus is diffused, giving an agreeable softness in place of the shallow plane of excessive and wiry definition so familiar to the photographer.