28MM SCREW MOUNT LENSES

2.8cm f/6.3 Hektor

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It is widely acknowledged that Max Berek was responsible for the development of the 2.8cm f/6.3 Hektor lens¹²¹. In his "Geburtstage der Leitz-Foto-Konstruktionen ab 1927" book, Wilhelm Albert dated the "birthday" of the coupled variant of this lens ("Objektiv Hektor 2,8 cm 1:6,3 mit E.-Kupplung") as September 25, 1934, and noted himself as designer⁵⁷³.

The 2.8cm f/6.3 Hektor lens was publicly demonstrated for the first time at the Spring Fair of 1935 (May of 1935¹²¹), on the 10th anniversary of the birth of Leica⁴⁷⁶.

The lens had 5-glass design of triplet configuration¹²¹. The optical design of this lens featured an enlarged front element, resulting in good central resolution at all apertures¹²¹. The use of special formula glass and a unique, patented banana-shaped iris diaphragm leaf enhanced its optical performance¹²¹.

While the maximum aperture of f/6.3 might seemed slow, it represented an impressive achievement in lens design, especially when one considered its angle of view at full aperture³⁵⁸. The lens had a field of view of 76 degrees diagonally, with a vertical angle of view of 46 degrees and a horizontal angle of 65 degrees, based on a 24 x 36mm image size³⁵⁸.

The lens weighted 100 grams¹²¹ and featured continental f-stops (6.3, 9, 12.5, 18, 25)¹²¹. The lens was compatible with 36mm (A36) push-on or 34mm screw-in filters¹²¹. The rotating lens mount could focus as close as 1 meter¹²¹. Distance scales were available in both feet and meters¹²¹.

Some lenses were supplied in tin tropical cases¹²¹.

Prototype

A known prototype of this lens was sold for 72000 Euros including buyer's premium at the 48th Leitz Photographica Auction on June 13, 2026⁵⁸⁵. It was described as "An exceptionally rare prototype of the Hektor 6.3/2.8cm from 1934, predating the official introduction of the production version in 1935...The mount bears the hand-engraved optical formula designation “B236,” a characteristic feature of experimental or developmental examples from this period.  Of particular significance, this example is ex Leitz Museum and is accompanied by the original museum inventory card, firmly documenting its provenance. The lens is illustrated in P.H. van Hasbroeck’s Leica in Colour, page 118...A highly significant and extremely scarce pre-war Leica prototype with distinguished provenance and published reference.".

Variants

There were 3 variants of this lens³⁶⁰:

• Code-named HOOPY⁸², the variant 1 came with the serial number engraved around the mount of the rear elements³⁶⁰. In order to see what the number was, one had to remove the lens from the body³⁶⁰. This variant had nickel finish³⁶⁰. Production of the rare nickel finish version ceased in 1937¹²¹. Nickel versions were only found in 250XXX and 273XXX batches³⁶⁰. No more than 200 lenses of this variant were made¹²¹. 
• Code-named HOOPY-CHROM¹²¹, the variant 2 was similar to Variant 1, but had chrome finish³⁶⁰. The production of this variant started in 1936³⁶⁰. The chrome version continued until production was halted by the war in 1942¹²¹ (or 1941³⁶¹). Reported serial number batches included 250XXX, 273XXX, 336XXX, 425XXX, and 580XXX¹²¹. According to Erwin Puts, the pre-war production ended with serial number 580350³⁶¹. Coated lenses appeared among the 580XXX batch from 1941 of this variant¹²¹. Approximately 8037 lenses of this variant were made¹²¹. 
• Code-named HOOPY-B (the "B" stands for Blau, or coated)¹²¹, the variant 3 came with a new international aperture scale³⁶⁰. The serial number was located on the ring around the front element of the lens³⁶⁰. This variant was reintroduced when production of 2.8cm f/6.3 Hektor resumed in 1950⁴⁷⁷ and was discontinued in July¹²¹ 1952³⁶⁰ produced in one serial number batch, 790101-791557¹²¹. All of these lenses featured rotary chrome mounts similar to the prewar version, used international f-stops (6.3, 8, 11, 16, 22), and were coated¹²¹. Approximately 1457 lenses of this variant were produced¹²¹.

Viewfinders

Viewfinders available for the lens included: 

• the folding bright line sports finder available in black (SUOOQ) or chrome (SUOOQ CHROM) finish from 1934 to 1940, though no parallax correction was provided¹²¹.
• 50mm reflecting waist-level finder (AHOOT) was supplied in black with a swinging negative front lens to convert to the 28mm field of view¹²¹. 
• in 1940, the Imarect (VIOOH) universal viewfinder with the TUVOO 28mm adapter was introduced at the Leipzig Fair¹²¹. TUVOO remained in production until 1963, with only minor changes in engraving¹²¹. 
• Ernst Leitz, New York, manufactured their iteration of TUVOO 28mm adapter, the extremely rare VIOAD 28mm adapter from 1941 to 1949, to be used with their iteration of the Imarect (VIOOH), known as IMFIN¹²¹.

Lens hoods

In 1934, a push-on, clamping, black round SOOHN lens hood was introduced with nickel fittings and metal-filled engraving¹²¹. This variant was quickly replaced with chrome set screw hoods and paint-filled engravings¹²¹. The hood was copied by Ernst Leitz, New York, during 1941-1949 in two versions¹²¹:

• one with a flat black interior and a dull brushed chrome exterior¹²¹
• the other with glossy black replacing the chrome exterior¹²¹

A close comparison of the Ernst Leitz, New York hoods with the Wetzlar version revealed only slight differences in the chamfer along the rim of the shade¹²¹. Today, SOOHN lens hoods are more difficult to acquire than the lens itself¹²¹.

Military

Among the lenses produced for the military were 2.8cm f/6.3 Hektor lenses produced for the Kriegsmarine (German Navy) were³⁸¹. There about 30 such lenses known to exist today³⁸¹. All of these lenses were delivered to Berlin on August 23, 1943 as a part of shipment number 9839³⁸⁴. Among the lenses delivered to the Kriegsmarine (German Navy) were:

• Lens number 580002, dated 1943, was sold for 3840 Euros including buyer's premium at the 42 Leitz Photographica Auction, on June 10, 2023, with the following description: "...engraved on the rear with 'W.haven'" and Reichsadler with an 'M'..."³⁸¹.
• Lens number 580140, dated 1943 (or 1941⁴¹⁸), was allegedly illustrated on page 95 of James L. Lager's of "Leica: An Illustrated History - Volume 1 - Cameras - Signed Deluxe Limited Edition" book³⁸¹. The lens was sold for 4126 Euros including buyer's premium at the 6 WestLicht Photographica Auction, on November 6, 2004, with the following description: "...engraved on the rear: 'W.haven' + Reichsadler"⁴¹⁸.
• Lens number 580175, dated 1943, was sold for 6000 Euros including buyer's premium at the 32 Leitz Photographica Auction, on March 10, 2018, with the following description: "...engraved on rear "W.haven" with "Reichsadler""³⁸⁴. Before that, it was sold for 3840 Euros including buyer's premium at the 12 WestLicht Photographica Auction, on November 17, 2007⁴¹².
• Lens number 580181, dated 1941, was sold for 7200 Euros including buyer's premium at the 22 WestLicht Photographica Auction, on November 24, 2012, with the following description: "...engraved on rear 'W.haven' with 'Reichsadler' + 'M' ...""⁴⁰². Before that, it was sold for 4800 Euros including buyer's premium at the 10 WestLicht Photographica Auction, on November 18, 2006⁴¹⁴.
• Lens number 580326, dated 1943, was sold for 2880 Euros including buyer's premium at the 39 Leitz Photographica Auction, on November 20, 2021, with the following description: "...engraved on rear with 'W.haven'" and Reichsadler......"³⁸⁴. Before that, this lens was sold for 3120 Euros including buyer's premium at the 38 Leitz Photographica Auction, on June 12, 2021³⁸⁵.

 

Closing Remarks

According to Helmut Lagler, there were 46404 lenses produced between 1935 and 1950, with serial numbers ranging from 250001 through 792000⁴³⁹.