Sun Optical Co. Sun Sola 9cm f/4 LTM

Sun Optical Co. Sun Sola 9cm f/4 LTM

The Sun Sola 9cm f/4 is a Japanese Leica screw-mount short telephoto lens made by Sun Optical Co. for 35mm rangefinder cameras. It belongs to the small group of early Japanese third-party LTM lenses made for Leica, Nicca, Leotax, Canon and other Leica-thread-mount bodies. Camerapedia documents the Sun Sola 9cm f/4 as a Leica screw-mount lens and separates it from other Sun LTM lenses such as the Sun Xebec 5cm f/2, Sun Sophia 5cm f/2, Sun Sola 7.5cm f/3.5 and Sun Telephoto 13.5cm lenses .

The lens is marked in centimeters as 9cm and has a maximum aperture of f/4. A Fotohandel Delfshaven listing describes a SUN 1:4 / 9cm lens for Leica screw mount as a 1950s Japanese third-party lens that resembles the Leica Elmar 9cm f/4 in build and optical concept. That listing records a metal housing, feet focusing scale, rotating front section, double aperture scale, 34mm filter thread and 12-blade aperture .

This lens should not be confused with the Leitz Elmar 9cm f/4. It is a Japanese Sun Optical lens with its own production history. It also should not be merged blindly with every Sun 90mm f/4 lens, because Sun made 9cm f/4 lenses in Leica screw mount, Exakta mount and 42mm screw mount. This entry covers the Leica L39 / LTM / M39 rangefinder-coupled version.

Optical qualities

Rendering

Reliable formal optical testing is limited. The available collector literature generally treats the Sun Sola 9cm f/4 as an Elmar-like compact telephoto. Camerapedia notes that many users who tried the lens reported favorable image quality and that it compared well with the Leica Elmar 9cm f/4, while also noting mixed reports for later examples.

Sharpness

Published laboratory testing is not widely available. Forum reports describe the lens as similar in size and image quality to the Leica Elmar 90mm f/4, with some users finding it slightly sharper, but this should be treated as user-level evidence rather than measured performance .

Contrast and coating

Coating and contrast depend on version and condition. Fotohandel Delfshaven describes one SUN 1:4 / 9cm example with slight coating marks on the front element, which shows that coating condition should be checked carefully on surviving copies.

Bokeh and transitions

The 12-blade aperture documented by Fotohandel Delfshaven supports rounded stopped-down aperture shapes. Because the lens is a 90mm f/4 telephoto, it can give moderate subject separation, but strong claims about bokeh character should be avoided without sample-specific testing.

Handling

The lens has Elmar-style handling characteristics. The front section rotates during focusing, so examples may have a double aperture scale to keep aperture markings readable during use. This is an important practical difference from later fixed-front telephoto designs.

Digital use

The lens can be used on Leica M cameras with an L39-to-M adapter and on mirrorless cameras with suitable adapters. Because this is a vintage rangefinder lens, infinity focus, rangefinder coupling and close-focus accuracy should be checked on the exact camera and adapter combination.

History

Development and Launch

Sun Optical Co. was an early Japanese third-party lens maker that produced lenses for several camera mounts, including Leica screw mount, Exakta and 42mm screw mount. Camerapedia states that the Sun line developed out of K.O.L. and Sun lenses in Leica screw mount, with Sun Sola 9cm f/4 appearing after the early postwar 7.5cm and 7.3cm lenses.

Production Evolution

Camerapedia describes an early Sun Sola 9cm f/4 in chromed brass, with serial numbers such as 73195, 80577 and 81147. It also describes a later alloy-barrel version with a leatherette band, inspired by the newer style of the Leica Elmar 9cm f/4 introduced in 1951. Later examples may be marked simply Sun 9cm f/4, while the later Xebec Telephoto 9cm f/4 appears to use a similar barrel form with black and silver finish.

Special Editions/Variants

No commemorative factory special edition is documented. The important collector distinctions are production and branding variants: early Sun Sola 9cm f/4 chrome version, later Sun Sola 9cm f/4 alloy version with leatherette band, later Sun 9cm f/4 examples without Sola branding, and Sun Xebec Telephoto 9cm f/4 examples. The Xebec versions are reported as rare and should be documented individually by engraving and serial number .

Collector Notes

Collectors should verify the front engraving, Sun, Sola or Xebec branding, Leica L39 / M39 mount, rangefinder coupling, serial number, filter thread, aperture blade count, infinity focus and optical condition. Because Sun made similar lenses in Exakta and 42mm screw mount, the mount and rangefinder coupling should not be assumed from the focal length alone. Important condition issues include haze, cleaning marks, coating marks, dry focusing spots, rotating-front wear and damaged 34mm filter threads.