150mm f/5.6 Symmar Convertible
Schneider 150mm f/5.6 Symmar Convertible, 49mm filters.
This is the sharpest lens I own, and it was made in 1955.
I was going to throw it away when it came all beat up on my Technika camera I thought, since it was all beat up and a foolish "convertible" lens, that it couldn't possibly be any good. Keeping an open mind I tried it, and it is the sharpest lens I own. HA! This is why I keep advising to ignore everything you read and hear and just go photograph for yourself.
For instance, Ansel Adams used a Cooke triple convertible for some of his most famous images according to an article by Gordon Hutchings in View Camera magazine, July/August 2004. Ansel used the 19" (480 mm) component for "Aspens, Northern New Mexico," 1958; both components to get 12" (300 mm) for "Clearing Winter Storm, Yosemite National Park," 1940; and the 23" (580 mm) component for "Moonrise, Hernandez, New Mexico," 1941. Enough said?
I tape my shutter speed correction to the lensboard so I always have perfect exposures.
It has a ten-bladed diaphragm. It goes past f/32 and stops at the equivalent of f/45. Use the black numbers; the green ones are for when you unscrew the front half of the lens and only use the rear cell. The rear cell alone gives you a 265 mm f/12 lens.
Six elements, three groups. Remove the front cell to leave the rear three element two group section for a 265 mm f/12 conversion.