Cooke PS945 229mm/9inch ƒ/4.5 multicoated lens in Copal No.3 shutter
The COOKE PS945 is a lens made in small quantities, to very high standards, in England. It has four air spaced elements with optically correct multi coatings and is fully color corrected. The image quality is excellent for color or B&W film and digital backs. It projects a sharp, high resolution image at f/4.5 with a softer secondary image overlying the primary. The images unify by about ƒ/8, very similar to the Pinkham & Smith Visual Quality lens image. The P&S lenses were made in Cambridge, Massachusetts, 1890 to 1930. Mark Gershman had my P&S lens, with its aspheric surfaces, while designing the PS945. He kept the image look, adjusted for the smaller 4x5 inch format and corrected the color aberration by using expensive high refractive index, low dispersion glass. As the aperture is closed down beyond f/11 the image becomes sharper, with very little secondary image. It becomes more diffracted as the aperture is closed down further to f/90 and makes an image which is smooth, with no distracting sharp plane of focus. Although designed for 4x5 inch format with some movements, hence 9"45 in the name, it covers 5x7 inch format on axis at ∞. The filter size is 77mm and the # 3 shutter fits on a 4" Linhof Technika type lens board.
New owner's response
This lens appears to be the best looking glass I've ever seen,... in any lens, gorgeous!!