Elmar 50 mm f:3,5 (III)

Características

Código - ELMAR, ELMAR-M - ELMAM 11110 11610 LLC - 113

Producción - 1954-1961 Bayoneta Leica-M < 47,364 ejemplares
Variantes Metrica, pies, A36 y E39
Montura -Bayoneta Leica M, Rosca M39
Angulo de visión (diagonal): 45º

Diseño Óptico:

Longtud focal efectiva -
Posición de la pupila de entrada
Número de lentes/grupos - 4/3

Intérvalo de enfoque: - 1 m a infinito
Escalas: en metros o pies
Campo visual mínimo:

Diafragma - f/3,5-f/22 con click, diafragma manual tipo iris de 10 hojas
Montura de filtros: A36 (rosca M39) rosca hembra interna E39 (Bayoneta M); frontal rota al enfocar
Parasol: 2585, 12549, ITOOY,
Accesorios:– Combination hood with diaphragm adjustment: VALOO; Hood for E39 version: ITOOY; Caps: ORVZO, ORVZO-CHROM

Longitud hasta la bayoneta -
Diámetro máximo -
Material: latón cromado y vidrio óptico
Peso - aprox. 125 g

Inscripción - Ernst Leitz GmbH Wetzlar - Elmar f=5cm 1:3.5 Nr.1XXXXXX
Diseño: Max Berek

Referencias

Marco Cavina

Descripción

This lens stands at the start of the Leica legend.

The original drawings of Max Berek have a date of May 6th, 1925 for this lens. Prof. Berek remarked in his “Principles of Practical Optics” (1930) that it is a derivative of the Cooke triplet, (designed by Taylor of the Cooke company). The cemented last group is needed for the required refractive index and he also moved the aperture position behind the first element, so creating some asymmetry in the design.

The Elmar has been in production for more than 35 years in countless versions that are a collector’s delight. At least 30 different versions have been identified and catalogued, but optically all were similar and had the same optical performance.

In the course of its long life many changes have been introduced, including changes in the optical specifications (glass types and shapes of glass elements). Most of these were introduced to ease manufacture or to adjust to new glass (as older types were no longer available or proved difficult or sensitive in use).

Almost 360.000 Elmar 3.5/50 mm lenses have been produced, which is about 13% of all Leica rangefinder lenses produced till 2011. An important change was the application of coating to the lens surfaces. It is not exactly known when the coating of lenses for civilian production of the Elmar 3.5/50 mm started after WW2, but mid 1946 is the most probable period. The serial # 581501 and 598201 are quoted most often, but the first number has been allocated in 1941 already for the Elmar 3.5/35 mm. The second number has been allocated in august 1945 and might be correct.

The application of coating did not enhance the performance very much as its moderate aperture and low number of air-glass surfaces could control flare and unwanted reflections very well. With strong backlight flare is obviously a problem.

The choice of the focal length of 50 mm for the Leica has a logical explanation. The usual definition of a standard lens is one that has a focal length equal to the diagonal of the negative area. For the Leica format that would be a focal length of 45 mm. Industry standards in that period introduced a tolerance of 6% for the stated focal length: a nominal/engraved focal length of 50 mm could be effectively varying between 47 mm and 53 mm. Berek opted for an effective focal length of 51.9 mm, which gave an angle of view of 45 degrees, less than what would be the standard 53 degrees. Berek knew that the Elmar was a bit weak in the corners and this would show when the negatives were enlarged. Therefore he restricted the angle of view to cut off the weak outer zone.

At maximum aperture the contrast is low and definition of fine detail is moderate. Stopped down the lens is a very fine performer. The reputation of the lens as being better than the contemporary Zeiss Tessar might be derived from loyalty to the marque. Optical experts in the 1930s often give the Tessar the highest praise. The Elmar has an interesting fingerprint that may explain the high esteem: a sharp central disc with crisp definition of main outlines and a blurring of fine detail in the zonal areas. The clean character of the delineation of major subject outlines and the somewhat grainy thick emulsions gave the final pictures a high impact.