Flor 55mm f/1.5

SOM Berthiot · LTM + Exakta + Leica M + Other · 1940

our own finding

Also known as: SOM Berthiot Flor 55mm f/1.5 · SOM Berthiot Flor 55mm f1.5 · Som Berthiot Flor 1.5/55mm · S.O.M. Berthiot Flor 55mm f/1.5 · Berthiot Flor 55mm f/1.5 · Berthiot Flor 5.5cm f/1.5 · Flor-Berthiot 55mm f/1.5 · Berthiot Flor 1:1.5 F=55mm · Berthiot Flor 1:1.5 F=5.5cm · Flor 1:1.5 F=55 · Flor 55mm f1.5 · Rectaflex Flor 55mm f1.5 · サン・ベルチオフロール 55mm F1.5

Variants & identification

Variant	Mount	Years	Serial ranges	Production
Leica screw mount, black front ring (1940s)	Leica M39, rangefinder-coupled	1940	283935 (Leitz Photographica Auction 49, lot 324) 283946 (oldlens.com, dated c.1940–42)	—
Leica screw mount, coupling by A. Garneau (1950s)	Leica M39, rangefinder coupling made for Berthiot by A. Garneau, Paris	—	452055 (Leitz Photographica Auction 40, lot 290)	—
Exakta bayonet	Exakta	—	289428 (Leitz Photographica Auction 41, lot 348)	—
Praktiflex 40mm screw mount	Praktiflex M40 screw mount	—	268229 (Leitz Photographica Auction 43, lot 328)	—
Rectaflex bayonet, on a Rectaflex 1300	Rectaflex	—	452242 (Leitz Photographica Auction 48, lot 280)	—
No. 970681, lens head in a modern Leica M helicoid	Leica M (later conversion: Hawk's Factory helicoid, made in Taiwan)	—	970681 (Leitz Photographica Auction 42, lot 375)	—

Specifications. Seven elements in five groups, 16 blades, f/16, 75cm and 500g are the oldlens.com owner's figures for his Leica-mount no. 283946; the closest focus and the weight belong to that mount. He gives the arrangement as a Gauss-type front with a rear group of Berthiot's own form, and says the f/2 and both f/1.5 Flors appear to share that layout.
One lens or two. No source says the 55mm and the 50mm f/1.5 are one design engraved two ways. oldlens.com, the one source that discusses both, says it is not clear why Berthiot made two, and suggests the 55mm was computed a little longer because it was meant for reflex cameras, citing examples on the Rectaflex, Exakta and M42, while noting that it was also supplied as the standard lens of rangefinders such as the Italian Gamma 2 and the French Lynx. No Gamma, Lynx or M42 example has been traced to a sale or a photograph. Every reflex example in these lots is a 55mm; none of the 50mm lots is in a Berthiot mount at all.
Market. Leitz results, buyer's premium included: €78,000 (Leica, Garneau, Auction 40), €66,000 (with a Rectaflex 1300, Auction 48), €40,800 (Praktiflex, Auction 43); the Exakta (Auction 41) and the M conversion (Auction 42) did not sell. The 1940s Leica lens in Auction 49 is estimated at €32,000–36,000.
Year. No launch year is published. 1940 is the start of oldlens.com's c.1940–42 for no. 283946, the earliest dated example.

How to tell them apart (expand)

Engraved F=55 (sellers write 55mm or 5.5cm); the f/1.5 Flor engraved F=50 is a different lens with its own page
Aperture 1:1.5 to 16; the 1940s heads have a black front ring engraved in white with 'F=55 Bté' before the number, the 1950s Garneau and Rectaflex examples a chrome one, with 'F=55 Nº' before the number on the Garneau lens; no. 970681, dated 1950s by Leitz, has a black ring with 'Nº' (Leitz lot photographs)

Leica screw mount, black front ring (1940s):

Black front ring engraved in white 'SOM BERTHIOT PARIS FLOR 1:1.5 F=55 Bté' and the serial number (Leitz lot photographs)
Chrome aperture ring scaled 1:1.5, 2, 2.8, 4, 5.6, 8, 11, 16 behind the front ring, and a broad chrome knurled focusing mount with a brass screw (Leitz lot photographs)
Two distance scales on the mount: 1, 1.25, 1.5 … on one side and 4, 5, 7, 10, 20, ∞ on the other (Leitz lot photographs)

Leica screw mount, coupling by A. Garneau (1950s):

Chrome front ring engraved 'Nº 452055 SOM BERTHIOT …' under a black filter rim (Leitz lot photograph)
Mount engraved '… DE PRECISION A. GARNEAU …' near the brass thread (Leitz lot photograph)
Distance scale reading … 2.5, 3, 4, 5, 8, ∞ (Leitz lot photograph)

Exakta bayonet:

Black front ring engraved with the serial number and 'SOM BERTHIOT PARIS' (Leitz lot photograph)
Chrome barrel with two diamond-knurled focusing grips, a distance scale ∞, 8, 5, 3 … and a depth-of-field scale in red from 1.5 to 16 either side of the index (Leitz lot photograph)

Praktiflex 40mm screw mount:

Black front ring engraved 'PARIS FLOR 1:1.5 F…' (Leitz lot photograph)
Chrome barrel with two pairs of diamond-knurled grips and a distance scale ∞, 8, 5, 3 …; a narrow thread and a black rear tube below (Leitz lot photograph)

Rectaflex bayonet, on a Rectaflex 1300:

Chrome front ring engraved 'SOM BERTHIOT …', the glass showing a coloured coating reflection (Leitz lot photograph)

No. 970681, lens head in a modern Leica M helicoid:

Black front ring engraved in white '…ERTHIOT PARIS FLOR 1:1.5 F=55 Nº 970681 SO…', chrome aperture ring 1:1.5 to 16 and a chrome knurled barrel (Leitz lot photographs)
Set into a black modern helicoid engraved 'HAWK'S FACTORY HELICOID MADE IN TAIWAN', with a metre scale and a Leica-style depth-of-field scale (Leitz lot photographs)

Leica screw mount, black front ring (1940s): Offered at Leitz Photographica Auction 49, lot 324, sale 28 November 2026: estimate €32,000–36,000, current bid €16,000 from one bid on 9 November 2026. Leitz grades it B+, dates it to the 1940s and describes it as 'in original RF coupled Leica M39 mount', with very good uncoated optics, rear cap and leather case. The oldlens.com owner's no. 283946, eleven numbers on, is in a Leica screw mount, weighs 500g and focuses to 75cm; he dates it c.1940–42 and, from a Flor 75mm f/2.8 bought at the same time with a number in the same 283,000 block and the same build, takes both to be original Leica mounts of one period. On his 55mm page, though, he suggests his lens was probably once fitted to one of the rangefinders the 55mm was supplied for, the Gamma 2 or the Lynx; the two statements are his and are not reconciled. Who made the coupling on these 1940s lenses is not recorded.
Leica screw mount, coupling by A. Garneau (1950s): Sold at Leitz Photographica Auction 40, lot 290, for €78,000 including buyer's premium, against an estimate of €60,000–70,000 and a starting price of €30,000, the highest price for an f/1.5 Flor in the Leitz results traced here. Leitz grades it B/A, dates it to the 1950s and calls it 'one of the rarest and most desirable third party lenses in original, rangefinder-coupled Leica mount', a brass barrel finished in bright chrome with the 'coupling made for Som Berthiot by A. Garneau, Paris (engraved accordingly)', and 'only a handful of these special lenses are known to exist'.
Exakta bayonet: Offered at Leitz Photographica Auction 41, lot 348, unsold against an estimate of €40,000–50,000 and a starting price of €20,000. Leitz grades it B/A, dates it to the 1940s, describes a brass barrel finished in bright chrome with good optics showing minor haze, and sold it with an Exabag adapter fitting it to an Alpa and an Alpa Mod. 6, no. 39040, in its case.
Praktiflex 40mm screw mount: Sold at Leitz Photographica Auction 43, lot 328, for €40,800 including buyer's premium, against an estimate of €40,000–45,000 and a starting price of €20,000. Leitz grades it B+, dates it to the 1940s and calls it 'sought-after and extremely rare … in original M40 Praktiflex mount', with its original short hood.
Rectaflex bayonet, on a Rectaflex 1300: Sold at Leitz Photographica Auction 48, lot 280, for €66,000 including buyer's premium, against an estimate of €28,000–32,000 and a starting price of €15,000, on a Rectaflex 1300 body no. 28349 graded B/A and dated to the 1950s; the lens graded B, with its original front cap. Its number is 187 above the Garneau-coupled Leica lens no. 452055.
No. 970681, lens head in a modern Leica M helicoid: Offered at Leitz Photographica Auction 42, lot 375, unsold against an estimate of €30,000–34,000 and a starting price of €15,000. Leitz grades it B/A, dates it to the 1950s, calls it 'extremely rare fast coated lens, here professionally adapted for Leica M-mount, rangefinder-coupled', with both caps and hood. The lot photographs show the helicoid engraved by Hawk's Factory of Taiwan, the same maker as on the 50mm f/1.5 no. 412707: a recent conversion, not a Berthiot mount.

Serial-range notes

268229–289428: The 1940s block: 268229 (Praktiflex), 283935 (Leica), 283946 (Leica, oldlens.com, c.1940–42) and 289428 (Exakta), all dated to the 1940s by Leitz or their owner. Berthiot numbered its lenses in one sequence across types, so a Flor 75mm f/2.8 sits in the same 283,000 block.
452055–452242: The 1950s pair: 452055 in the Garneau-coupled Leica mount and 452242 on a Rectaflex 1300, both with chrome front rings.
970681: Leitz dates it to the 1950s and calls it coated. A Berthiot Flor 50mm f/2.8 no. 948598 is dated to the 1960s by the same house, so the two dates do not sit easily together; both are given as Leitz gives them.

Specifications

Formula: Modified double Gauss: Gauss-type front group with a rear group of Berthiot's own form (oldlens.com)
Construction: 7 elements / 5 groups
Aperture range: f/1.5–f/16
Diaphragm blades: 16
Min. focus: 0.75 m
Weight: 500 g
Country: France

What reviewers say

oldlens.com (blog) — On his Leica-mount no. 283946 he finds it quite soft wide open, with strong swirl and a three-dimensional rendering he has seen from no other lens; he calls it under-corrected for spherical aberration with residual astigmatism and coma, giving double-line foreground blur and soft background blur, while the plane of focus stays reasonably sharp.

History

The Flor 55mm f/1.5 is the better known of Berthiot’s two f/1.5 Flors, and much the more valuable. It is a fast double-Gauss derivative of seven elements in five groups, with a Gauss-type front and a rear group of Berthiot’s own form, stopping down to f/16 with a sixteen-blade iris. Berthiot made it for several cameras. Auction lots and photographs show it in Leica thread, Exakta, Praktiflex and Rectaflex mounts, from serial numbers in the 268,000s in the 1940s to the 452,000s in the 1950s. The one owner who has written about it at length suggests it was computed slightly long, at 55mm, because it was meant for reflex cameras. He also notes that it was offered as the standard lens of French and Italian rangefinders, the Lynx and the Gamma, though no such outfit has been traced.

Leitz treats the Leica-thread lenses as original, not conversions. It describes both the 1940s lens in Auction 49 and the 1950s lens it sold for €78,000 as being in original rangefinder-coupled Leica mount. The later of the two carries the name of A. Garneau of Paris, who made the coupling for Berthiot. The 1940s lenses have a black front ring engraved in white and a broad chrome focusing mount with two distance scales. The 1950s Garneau and Rectaflex lenses have chrome front rings. The one Leica M example is a different matter: Leitz calls it professionally adapted, and its photographs show the head in a modern helicoid, so it is a recent conversion.

Wide open it is soft, with strong swirl in the background and doubled lines in out-of-focus foregrounds. Its owner at oldlens.com puts this down to under-corrected spherical aberration with astigmatism and coma left in, and Leitz, selling one on a Rectaflex, called the rendering sought after by collectors and filmmakers alike. The Flor engraved F=50 at the same aperture is kept on its own page. No source shows the two to be one design, the source that discusses both cannot say why there are two, and every example of the 50mm known so far is a lens head in someone else’s mount.

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This history is AI-written, from the sources listed at the foot of the page. Where the record is silent it says so rather than filling the gap — but no human wrote these sentences.

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