The regular R. R. and meniscus lenses used on Kodak and Brownie Cameras have always been the best lenses of their respective types that could be secured. These lenses are perfectly adapted to everyday amateur photography, producing pictures under normal light conditions that leave nothing to be desired by the average amateur.

For those, however, who wish even greater efficiency and capabilities, we supply the anastigmat lens equipments.

The superiority of the anastigmat lens, without attempting to go into the technicalities of the subject, consists of—Perfect definition over the whole negative, absolute flatness of field, and higher speed.

In R. R. lenses the tendency to lack of definition toward the edges, which always occurs in an uncorrected lens, is so slight as to be unnoticeable except to the most expert eye. In a true anastigmat, it is entirely eliminated.

The speed of a lens is determined by the relative size of the diaphragm opening. An R. R. lens cannot be used at an opening greater than ? its focal length, commonly designated as f. 8. But an anastigmat lens can be so corrected as to permit the use of larger diaphragm openings and still produce sharp, clear negatives. This larger opening admits more light within a given time than that of the R. R. lens, hence the anastigmat is much faster. Thus the Zeiss or Cooke Kodak Anastigmat lens, working at an aperture of f. 6.3 admits 60 per cent. more light in a given time than does the R. R.

This speed advantage enables the user to make short exposures on dull days or under poor light conditions, where hopelessly undertimed negatives would result with an R. R. lens. And under proper conditions, exposures up to 1/250 second with a Compound shutter and 1/1000 with a focal plane shutter, can be made with the anastigmat.

In the last few years there has been a steadily increasing interest in and demand for anastigmat lens equipments among amateur photographers, and we responded to this demand, first by furnishing the Special Kodaks fitted with Zeiss Kodak Anastigmat lens, f. 6.3—a lens fully corrected and offering the advantage of high speed.

These have been followed by the Six-Three Kodaks. These differ from the Specials in that they are simply our regular Kodak models, without the special covering and finish of "Specials," and fitted with anastigmat lenses specially designed by Taylor, Taylor & Hobson, for Kodak use and called the Cooke Kodak Anastigmat. This lens works at f. 6.3 and is fully corrected in every particular.