Photography literally means “drawing with light”, and perhaps the greatest influence on any “light drawing” is the lens used to form the image being recorded. Some photographers strive for perfect sharpness throughout their images, while others choose selective focus to express a more abstract view. The well-known Group f/64 advocated sharp, detailed photography – many of its adherents probably knew better than to actually use such a small lens aperture routinely, but the name was antithetical to the wide apertures often used by pictorial photographers to achieve a softer, more impressionistic look. As large-format lens designs improved during the first half of the twentieth century, image sharpness increased as optical aberrations diminished, so some pictorial photographers of the time had lenses designed to yield an intentionally “less than perfect” result for their impressionistic images. A series of such lenses was designed by the Boston optics firm of Pinkham & Smith specifically for pictorial photography, and one of the most notable from this group was the Visual Quality Series IV 9 inch f-4.5 lens, which combined very sharp performance at smaller apertures settings with a wonderful highlight diffusion at wider apertures. This combination of sharpness and softness could be controlled by varying the aperture setting, giving photographers a very interesting tool for their “light drawing ” kit.

UK-based Cooke Optics (www.cookeoptics.com) has re-created this legendary optical design in their recently-introduced PS945 soft-focus lens, complete with the original aspheric elements, but with modern coatings to improve color and reduce internal reflections. These limited-production lenses are more expensive than typical large-format optics, but offer some unique options for the discerning photographer. One factor driving price is the relatively large maximum aperture of f-4.5 for a 229mm lens, requiring substantial elements and a Copal 3 shutter. However, examining a few images from this lens quickly renders price secondary to less tangible qualities it offers, quite literally unlike anything one has seen before.

The following is from Cooke’s description of the PS945:  "The original Pinkham & Smith lenses achieve their distinctive soft focus in a manner different from other lenses. Using the traditional glass available at the time, craftsmen hand-corrected multiple surfaces of the lenses to achieve their unique soft focus look. The introduction of aspherical surfaces gave Pinkham & Smith lenses a higher-order spherical aberration that results (when the lens was used fully open) in an image with both very high resolution and a self-luminescent quality. Cooke has reproduced the unique performance of these hand aspherized lenses using modern design techniques that duplicate this unique soft yet high-resolution performance exactly.”

Most photographers understand that the high resolution of Better Light’s large-format digital scanning backs can deliver sharply detailed images, but not as many realize that the wide dynamic range and low noise of these unique image capture devices also make them perfect for rendering softer images with subtle gradations. The combination of a high resolution digital back with a soft-focus lens might at first seem improbable, but in many ways these unique optics have never looked better. Using wide aperture settings also lets more light into the camera, allowing fast scan times at low ISO settings, for optimum results.

 

After some delay while waiting for another batch of Copal #3 shutters to be produced (!), Better Light recently took delivery of Cooke PS945 serial number 0058. Here are a few initial test shots using this lens at its widest aperture setting, where it produces the most pronounced soft-focus effect. A model 6000-HS captured these images at its full resolution of 6,000 x 8,000 true RGB pixels, generating uninterpolated 274 Mbyte 48-bit files fairly quickly, thanks in part to the wide lens aperture. The examples on this page are each 600 x 800 pixels in size, so the overall 6,000 x 8,000 pixel image would be ten times larger in each direction. On a computer monitor with 100 pixels per inch (a pixel pitch of 0.25mm), each full-resolution image section should be displayed at about the same size that it would appear in a 60 x 80 inch print of the overall image.

 

“BACKYARD IN RAIN” – (at left and below ) was captured during a light rain one evening in January, which is why there are no leaves on the birch trees. The camera’s plane of focus was placed along the foreground light post and nearest corner of the gazebo by using appropriate front swing. Most of the original image (shown at left) was very dark when the light fixtures were properly exposed, suggesting that I missed the optimum time for this photograph. However, I was able to selectively brighten things up by several f-stops without introducing much noise (below). The overall image below exhibits a dreamy softness in its out-of-focus background, with a halo of diffusion around bright objects everywhere in the scene.