28MM SCREW MOUNT LENSES


A vintage Leica Hektor camera lens with focus and aperture markings, placed on a white background with a lens cap nearby.

2.8cm f/6.3 Hektor

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 in 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 seem 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 was compatible with 36mm (A36) push-on or 34mm screw-in filters121. The rotating lens mount could focus as close as 1 meter121. 

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 6 variants of this lens:

Variant 1 was:

  • code-named HOOPY82
  • finished in nickel360.
  • 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.
  • had continental f-stops (6.3, 9, 12.5, 18, 25)
  • had "Germany" engraving
  • feet scale, engraved "Feet" with capital "i"
  • No more than 200 lenses of Variant 1 + Variant 2 were made121.
  • The lens weighed 100 grams121.
  • Examples of lenses of this variant included: 250005, 250025, 250052, 250091, 273176, 273395


Variant 2 was:

  • code-named HOOPY82
  • finished in nickel360.
  • 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.
  • had continental f-stops (6.3, 9, 12.5, 18, 25)
  • no "Germany" engraving
  • meter scale, engraved "mtr"
  • Production of Variant 2 ceased in 1937121.
  • No more than 200 lenses of Variant 1 + Variant 2 were made121.
  • The lens weighed 100 grams121.
  • Examples of lenses of this variant included: 250322, 250693, 250715, 250718, 250755, 250767, 250778, 250793, 250845, 250891, 273616, 273677, 273705, 273797, 274267, 274347


Variant 3 was:

  • code-named HOOPY-CHROM121.
  • finished in chrome
  • had continental f-stops (6.3, 9, 12.5, 18, 25)
  • no "Germany" engraving
  • meter scale, engraved "mtr"
  • The production of this variant started in 1936360.
  • Coated lenses appeared in the 580XXX  batch from 1941 of this variant121 .
  • Approximately 8037 lenses of Variant 3 + Variant 4 + Variant 5 were made121 .
  • The lens weighed 100 grams 121 .
  • Examples of lenses of this variant included: 250385, 250435, 250437 ,  273106 ,  273294 ,  273317 ,  273410 ,  273600 ,  273722 ,  273748 ,  273767 ,  274681 ,  274782 ,  274797 ,  274891 (delivered to the Gestapo, engraved 'Re.370295' (Reichssicherheitshauptamt Gestapo)) ,  274915 ,  336252 ,  336264 ,  336308 ,  336485 ,  336672 ,  336953 ,  357160 ,  357242 ,  357315 ,  357430 ,  357908 ,  357933 ,  425074 ,  425186 ,  425289 ,  425387 ,  425421 ,  425708 ,  425829 ,  452104 ,  452367 ,  452370 ,  495350 ,  495422 ,  495539 ,  495557 ,  495758 ,  531239 ,  531341*  ( double delivery) ,  541545 ,  541571 ,  541674 ,  580181 ,  580251
  • According to the 46th Leitz Photographica Auction catalog, Leica records shows that all Hektor lenses between 531201-531400 were double delivery


Variant 4 was:

  • code-named HOOPY-CHROM121.
  • finished in chrome
  • had continental f-stops (6.3, 9, 12.5, 18, 25)
  • had "Germany" engraving
  • feet scale, engraved "Feet" with capital "F"
  • Coated lenses appeared in the 580XXX  batch from 1941 of this variant121 .
  • Approximately 8037 lenses of Variant 3 + Variant 4 + Variant 5 were made121 .
  • The lens weighed 100 grams 121 .
  • Examples of lenses of this variant included: 531171, 580029, 580186


Variant 5 was:

  • code-named HOOPY-CHROM121.
  • finished in chrome
  • had continental f-stops (6.3, 9, 12.5, 18, 25)
  • had "Germany" engraving
  • meter scale, engraved "mtr"
  • production was halted by the war in 1942121. According to Erwin Puts, the pre-war production ended with serial number 580350361.
  • Coated lenses appeared in the 580XXX  batch from 1941 of this variant121 .
  • Approximately 8037 lenses of Variant 3 + Variant 4 + Variant 5 were made121 .
  • The lens weighed 100 grams 121 .
  • Examples of lenses of this variant included: 531175, 531201* ( double delivery) ,  531216*  ( double delivery) ,  531374*  ( double delivery) ,  541680 ,  580002 ,  580022 ,  580175 ,  580326
  • According to the 46th Leitz Photographica Auction catalog, Leica records shows that all Hektor lenses between 531201-531400 were double delivery


Variant 6 was:

  • code-named HOOPY-B (the "B" stood for Blau, or coated)121.
  • finished in chrome
  • had international f-stops (6.3, 8, 11, 16, 22)
  • had "Germany" engraving
  • meter scale, engraved "m"
  • The serial number was located on the ring around the front element of the lens360.
  • 2.8cm f/6.3 Hektor was reintroduced with this variant, when production resumed in 1950477.
  • featured rotary chrome mounts similar to the prewar version121.
  • Approximately 1457 lenses of Variant 6 + Variant 7 were produced121.
  • Examples of lenses of this variant included: 790195, 790709, 790938, 791276


Variant 7 was:

  • code-named HOOPY-B (the "B" stood for Blau, or coated)121.
  • finished in chrome
  • had international f-stops (6.3, 8, 11, 16, 22)
  • had "Germany" engraving
  • feet scale, engraved "feet" with lowercase "f"
  • production of 2.8cm f/6.3 Hektor ceased  with this variant, when production was halted in July121 of 1952360 .
  • featured rotary chrome mounts similar to the prewar version121.
  • Approximately 1457 lenses of Variant 6 + Variant 7 were produced121.
  • Examples of lenses of this variant included: 790357, 791152, 791317, 791398 (without "cm" engraving after "2,8")



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.

Close-up of a vintage silver camera lens with engraved text, placed on a plain white background.


2.8cm f/5.6 Summaron 

 In his "Geburtstage der Leitz-Foto-Konstruktionen ab 1927" book, Wilhelm Albert dated the "birthday" of the 2.8cm f/5.6 lens with linear guide ("Objektiv Summaron f=2,8 cm 1:5,6 mit Geradführung") as March 5, 1952, and noted Werner Schlapp as designer573. 

Prototype

The following prototypes of 2.8cm f/5.6 Summaron lens were known:

  • Prototype number 0000051 was auctioned off at the 5th Wetzlar Camera Auctions. It was described as "Experimental model of a 2,8 cm Leica lens, as the successor to the Hektor 2,8 cm f/6.3. That aperture setting ring is already engraved up to 5.6 and already similar in design to that of the later Summaron. However, the depth-of-field scale is still engraved with 6.3 as the largest aperture. Only three specimens of this unusual prototype version have been completed. The prototype numbers 0000049-51 were used. The prototype number is hand-scratched in the back of the lens mount..." 
  • Prototype number 0000058 was auctioned off at OstLicht Auction on May 28, 2026. According to Paul-Henry van Hasbroeck, Leitz reserved the serial numbers 0000058-0000069 for the prototype 2.8cm f/5.6 Summaron lenses, but only about 5 lenses were really finished.
  • Prototype number 0000067  was auctioned off at OstLicht Auction in spring of 2024. Before that, the lens auctioned off at the 24th WestLicht Photographica Auction and was described as "'B280*' formula engraved on rear mount, front ring with different engraving style ". This lens belonged to Paul-Henry van Hasbroeck collection. According to Paul-Henry van Hasbroeck, Leitz reserved the serial numbers 0000058-0000069 for the prototype 2.8cm f/5.6 Summaron lenses, but only about 5 lenses were really finished.
  • Prototype number 0000150 (hand-engraved on the mount with optical formula number B632) was auctioned off at the 48th Leitz Photographica Auction and before that the 39th Leitz Photographica Auction.
  • Prototype number 0000278 was auctioned off at 36th Leitz Photographica Auction and had black depth of field scale. 
  •  Prototype number 1231073 was  auctioned off at 36th Leitz Photographica Auction and was described as "a very interesting advanced prototype of the 2.8cm Summaron, showing several differences against the production models, like the completely different construction of the front rim, different aperture ring, no close-focus locking pin, etc.".  



An interesting unnumbered prototype in A42 screw mount was illustrated on a Leica IIIg camera number 888371 in Mr. Lars Netopil's "Rare Leica" book in 2014594. This outfit was later sold at the 7th Wetzlar Camera Auctions.


Pre-series

There were 2 pre-series variants of this lens:

Variant 1 was:

  • considered pre-series
  • some of the examples had different style of engravings to the production series
  • had feet scale
  • Examples included: 1325021, 1325036, 1325078, 1325130, 1363437

Variant 2 was:

  • considered pre-series
  • some of the examples had different style of engravings to the production series
  • had meter scale
  • Examples included: 1325075, 1325253, 1325292, 1363132


Serial Production

The 2.8cm f/5.6 Summaron lens was introduced to the public in 1955 as a replacement for the 2.8cm f/6.3 Hektor lens121. This lens, code-named SNOOX, had f stops of 5.6, 8, 11, 16 and 22 and featured a chrome parallel focusing mount that carried a symmetrical 6-element doublet optical design121. The parallel focusing mount ensured that the lens didn't rotate during focusing542. It featured distance scale in feet, in meters, and the very late models were reported to have a dual scale121. The lenses with metric scale were listed under catalogue number 11501, while those with imperial scale were listed under catalogue number 11001361. Click stops were present on the aperture ring, and A36 filters were compatible121. The near focusing distance for the lens was 1 meter121. The serial number was engraved on the rear of the lens mount542.

There were 2 serial production variants of this lens:

Variant 1 was:

  • considered serial production
  • had feet scale
  • Examples included: 1412120, 1412958, 1477430, 1502104, 1502331, 1502386, 1557300

Variant 2 was:

  • considered serial production
  • had meter scale
  • Examples included: 1412100, 1412840, 1413112, 1413228, 1413275, 1501966, 1537019, 1537109, 1537187, 1537244, 1537252, 1537263, 1557052, 1557351, 1557401, 1557773, 1875132, 1875153, 1875168, 1875169, 1875329, 1875391


Lenses for Post Office Use

Some 2.8cm f/5.6 Summaron were made for use in post offices. Most of the lenses of this variant came from a unique batch of 200 lenses, factory modified with M-bayonet (no.2279601-2279800) issued in 1968, long after the official serial production stopped377. However, there are known lenses of this type beyond 2279800. Erwin Puts also claimed that the last batch of 2.8cm f/5.6 Summaron lens was made in 1971 for the Post Camera, confirming this theory361. All such lenses familiar to the author of this website had meter scale. Examples of lenses for post office use included: unnumbered one that was mounted on Leica MDa Post 24x27mm number 1206956, 2279768, 2279784, 2499118

Leica Ig Post Camera number 987522, dated 1960, together with a modified Summaron 5.6/2.8cm no.1557778, was auctioned off at the 49th Leitz Photographica Auction on November 28, 2026605. 


Viewfinder

Viewfinders for this lens included:

  • TUVOO 28mm adapter121 (that could be used together with VIOOH542). In his "Geburtstage der Leitz-Foto-Konstruktionen ab 1927" book, Wilhelm Albert dated the "birthday" of the 2.8 cm telescope viewfinder attachment, known today as TUVOO, ("2,8 cm Suchervorsatz für Fernrohrsucher") as April 25, 1939, and noted himself as designer573. 
  • 28mm chrome bright line finder code-named SLOOZ121. In his "Geburtstage der Leitz-Foto-Konstruktionen ab 1927" book, Wilhelm Albert dated the "birthday" of this viewfinder ("2,8 cm sucher") as October 24, 1955, and noted Werner Schlapp as designer573. 


Lens Hood

The front element was significantly recessed into the barrel and typically did not require an accessory sunshade, although the SOOBK lens hood was designed for it241. The two versions of this rectangular lens hood were:121

  • The first version was engraved with "SOOBK 1: 5.6/2.8"121
  • The second version was engraved with "Summaron 2.8 cm" and had the catalogue number 12500121. In his "Geburtstage der Leitz-Foto-Konstruktionen ab 1927" book, Wilhelm Albert dated the "birthday" of the variant with same engraving ("Eckige Sonnenblende für Objectiv f=2,8 cm 1:5,6") as November 1, 1955, and noted Werner Schlapp as designer573. 


Adapters

The bayonet adapter ring (IRZOO / 14097) allowed the 2.8cm f/5.6 Summaron to be used with M cameras121. At the time of manufacture, this adapter ring was suitable for both 2.8cm and 21mm lenses, which required a separate finder for use235. Additionally, a 90mm adapter (ISBOO / 14098) was necessary to display the 28mm frame lines in the Leica M6 viewfinder235. The early 90mm adapters could not be used, as they were not cut away and interfered with the infinity lock of the 2.8cm f/5.6 Summaron lens235. It was presumed that the 2.8cm f/6.3 Hektor lens had a similar issue235. If your camera body had 28mm viewfinder framelines, the 90mm adapter will display them241. The production of the Leica adapters was discontinued long before the Leica M4-P, which introduced 28mm frame lines, alongside the 90mm235.


Closing Remarks

Production of the 2.8cm f/5.6 Summaron ceased in 1963121, shortly before the first 2.8cm f/2.8 Elmarit lens became available for M cameras312. A total of 6228 of 2.8cm f/5.6 Summaron lenses were delivered121. The serial number batches included: 1325xxx (pre-series), 1363xxx (pre-series), 1412XXX, 1413XXX, 1477XXX, 1501XXX, 1502XXX, 1537XXX, 1557XXX, and 1875XXX.