The single lens is not free from distortion. The marginal rays are apt to give the barrel-shape figure to the view, but for landscapes this is practically of little or no consequence.
The smaller sizes of single lenses are more effective than the larger. They are quicker and have much less distortion, and when stopped very small have practically none.
THE DOUBLE COMBINATION
is formed by reversing the single lens and making it the front lens of the double combination, and adding a similarly constructed achromatic lens to the rear. These lenses are indispensable for very rapid work and for work requiring straight lines. As the double combination is more perfectly corrected for spherical aberration, it is better adapted for architectural and other work not admitting of distortion. Of this class of lenses we would recommend ANTHONY'S RAPID DRY PLATE LENS, p159 which has a double achromatic combination for making instantaneous views, portraits groups, etc., and will meet all the requirements of those who do not care to incur the expense of a Dallmeyer or other first-class lens.
ANTHONY'S RAPID DRY PLATE LENS
[THE PLATYSCOPE LENS]
Of a higher class is THE PLATYSCOPE LENS, which is a rectilinear or perfectly corrected lens of great working rapidity, and is well suited for all the requirements of the amateur; and as to price, it holds a middle place and next to the DALLMEYER'S RAPID RECTILINEAR LENS, which is the most perfect instrument at present known to the profession, and is almost universally used by professional out-door photographers and by all amateurs who care to produce the finest possible work. This lens might be considered indispensable for all p160 work requiring an instantaneous exposure, as by means of the dry plate and the drop shutter some very remarkable pictures have been made of bodies in rapid motion.
