Many photographers have bought two lenses and one shutter with the idea of extending the focal length range. Two 19" ( 476 mm ) elements make a symmetrical lens of 273 mm, and two 25 1/2" ( 646 mm ) elements make a 368 mm lens. The sequence is 273mm/10.75" f.5.6, 311, 368mm/14.5" f/8, 476 f/11, and 646 mm f/16. These focal lengths cover 8x10 with generous movements. Although this lens was not designed for 11x14 the shortest fl may vignette, but all the rest cover.

DESCRIPTION

The COOKE XVa is a lens made in small quantities, to very high standards, with multicoated surfaces and full COLOR CORRECTION, so good for color film and digital backs. The single elements are also color corrected making this a big improvement over the original Cooke XV. The use of lanthanum glass in two of the elements allow the material to do more of the work in forming the image, so the curves of the surfaces can be flatter. This also makes the quality of the image from single elements about five times as good as the original series XV made in the 1930s. There is no need for filters to sharpen the image in black and white. It projects a sharp, high resolution, high contrast image at f/6.8 on 8" x 10" film. The individual elements are f/11 and f/16 and they too project a sharp color corrected image on 8"x 10". A # 3 shutter fits on a 4" Linhof Technika type lens board and is available from S.K. Grimes. Also available from S.K.Grimes are some very nice inner lens caps, available here http://skgrimes.com/thisweek/Cooke/index.htm