The Sonnar series of lenses evolved fairly rapidly in the 1930s. Every year seemed to bring a change in the mechanical construction, materials used, and optical formula. In 1935 Zeiss brought in the equipment to apply coatings to optics. By 1938 coated lenses were marked with a "T" for transparent. Zeiss introduced this new technique slowly, I've seen two Sonnars from 1935 with coated front elements. I have two 1936 Sonnars with SN different of ~70 units, one coated the other uncoated.
These are with my earliest Sonnar "T" from 1938. This lens is marked for F11, but stops down to F16. Glass is near perfect, some slight coating wear on the surface behind the aperture.
The Optical formula changed dramatically in 1939, I have a separate thread for those Sonnars.
All shots are Wide-Open at F1.5.
Into the sun. This lens has Flare and makes it look good.
The coatings increase contrast, and reduce veiling flare. Coated Sonnars with this optical formula are very rare. This is the only one marked "T" that I've handled.
These are with my earliest Sonnar "T" from 1938. This lens is marked for F11, but stops down to F16. Glass is near perfect, some slight coating wear on the surface behind the aperture.
The Optical formula changed dramatically in 1939, I have a separate thread for those Sonnars.
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All shots are Wide-Open at F1.5.
Join to see EXIF info for this image (if available)
Into the sun. This lens has Flare and makes it look good.
Join to see EXIF info for this image (if available)
The coatings increase contrast, and reduce veiling flare. Coated Sonnars with this optical formula are very rare. This is the only one marked "T" that I've handled.