Biotar 7.5cm f/1.5

Carl Zeiss Jena · Contax RF · 1940

single source, unconfirmed our own finding

Known as “King of Bokeh”

Also known as: Zeiss Biotar 75mm f/1.5 · Biotar 7.5cm f1.5 · Biotar 1.5/75 · Biotar 1,5/7,5cm

Variants & identification

Variant	Mount	Years	Serial ranges	Production
Prewar, chrome over brass	Contax RF	1940–1940	2759801–2759900 — one batch, 1940, on Pacific Rim Camera's account; the block falls in camera-wiki's 1941 band	About 100 (Pacific Rim Camera, the only source to record a prewar Contax batch — see the table notes)
Postwar Jena, first batch (December 1950)	Contax RF	1950–1950	from 3467751 — the opening number of the Contax rangefinder production (The Lens DB; Cheyenne Morrison's mount table). Leitz Auction's no. 3467776 sits 25 numbers in	100 (The Lens DB; Thiele's factory books are the likely origin)
Postwar Jena, second batch (1954)	Contax RF	1954–1954	3945251 — a lens in original Contax mount that Thiele's catalogue dates to 1954, reported by Roland Bischoff in the comments on Casual Photophile; the batch's opening number is not published	125 (The Lens DB; Thiele's factory books are the likely origin)

The postwar count. The Lens DB gives 225 lenses for the Contax rangefinder, 100 in December 1950 and 125 in 1954; Cheyenne Morrison's mount table on Casual Photophile gives the same 225 from no. 3,467,751 in 1950. Neither names its source, and both almost certainly rest on Hartmut Thiele's transcription of the Jena factory books, which is what Roland Bischoff dates individual lenses from in the same article's comments — two publications, then, but not two independent counts. Leitz Auction's catalogue rounds it to "only around 200 produced".
A different count exists and is not small. On Rangefinderforum on 23 March 2010, dexdog wrote that John Keesing's Contax Rangefinder Lenses 1932–1962 puts the number made at about 800. Keesing's book was not consulted for this entry; whether his 800 counts the prewar batch, the remounts, or something else is unknown. The 225 is the figure with a factory-book pedigree; the 800 is recorded so a reader who meets it knows where it comes from.
The prewar batch rests on Pacific Rim Camera alone: "one batch of about 100 examples was produced, serial numbers 2759801 to 2759900", in 1940, six elements in four groups, in a heavy chrome-over-brass barrel. Neither camera-wiki nor English Wikipedia lists a Biotar 75 among the prewar Contax lenses — both place it only among the postwar Jena alloy lenses — and Morrison's mount table has no prewar Contax row. Pacific Rim Camera is the source that prints batch numbers for the other Contax lenses on this site, so the batch is carried as a variant, but it is a single-source claim and the badge applies.
The lens is a small offshoot of a much larger SLR lens. On zeissikonveb.de, Marco Kröger dates the design to 20 April 1938 and production to February 1939, for Ihagee's Kine Exakta, and says the optical calculation of that date was never revised until the lens was dropped in 1969; he counts "knapp 20.000" lenses over thirty years, in lots of 100, 150, 200 or at most 300, usually one lot per mount per year, which is why the lens was hard to get even when it was current. Morrison counts 16,827 from 1939 to 1967 in three versions and six mounts, and tabulates them: Exakta 10,300 from no. 2,529,100 (1939), Contax S/M42 4,600 (1949), Praktina 1,250 (1953), Contax rangefinder 225 (1950), Leica thread 3 (1950). Stephen Gandy puts about 80% of the 75 Biotars he has seen in Exakta mount. None of the SLR versions is a variant on this page, which is the Contax rangefinder lens; the Exakta, M42 and Praktina lenses want a page of their own.
The barrel the Contax lens wears. Morrison's three versions are the prewar "thin" lens of 1939–45 (380 g, 18 blades, f/22, minimum focus 0.9 m, numbers in the 2,000,000s), the postwar "slim" lens of 1946–52 (chromed steel, T-coated, 18 blades, 500 g, numbers 3,100,000–3,777,000) and the "fat" preset lens of 1952–67 (10 or 12 blades, 500 g, numbers 3,777,000–8,275,578). Bischoff's 1954 Contax-mount lens no. 3945251 is a slim barrel with 18 blades and f/22, well above 3,777,000: the Contax lens kept the earlier barrel after the SLR lenses had moved to the fat one, and Morrison's serial boundaries are looser than they read.
A Leica-thread version existed and is rarer still. Kröger has a few single examples fitted with rangefinder coupling in summer 1948 and cannot say why so few; Morrison's table has 3 in 1950 and lists nos. 3467786 and 3320814 (her third number repeats the first); Marc James Small's Non-Leitz Leica Thread-Mount Lenses (Wittig, 1997) knew of two, as JB-Dancer cited it on Rangefinderforum on 14 June 2018, and a commenter on Morrison's article says he found the third, in a junk box in Omaha for $20. It is not a variant here because the numbers do not cohere — 3467786 sits inside the 1950 Contax batch, 3320814 in the 1949–52 M42 run — and because a Biotar 75 in 39mm thread is far more likely a later conversion; retinax's advice in the same thread is to check first whether the thread is Leica's or the Zenit SLR's, which is the same 39mm at a different register.
Weight, filter and focus. Gandy gives 19 oz "even with the aluminum barrel" and a 58mm filter, with the focusing scale in metres and feet; Morrison gives 500 g for the slim and fat barrels and 380 g for the prewar one, and weighed her own fat lens at 450 g. 19 oz is 540 g. The spec table carries 500 for the postwar lenses; the prewar chrome lens will weigh what its chrome-over-brass barrel makes it, and no figure for it has been found. Gandy also reports that all the 1950s Jena 75 Biotars were coated and in aluminium rather than chrome barrels, which covers both postwar Contax batches. The Lens DB gives the Contax lens a minimum focus of 1.1 m, against 1 m for its Exakta and Leica-thread lenses and Morrison's 0.8–0.9 m for the SLR barrels; the external-bayonet helicoid sets its own near limit.
No finder was made for it. Seller listings on eBay Germany offer a "Zeiss Ikon 75mm Sucher 423 für Biotar 7,5cm Contax RF", but Pacific Rim Camera is explicit that although Zeiss offered finders for a 75mm lens, "these were not designed for the Biotar. They are for the 75mm Pantar when used on the Contina III." A 423 finder frames the focal length and nothing more.
What the lens cost. Kröger gives 472 Mark in the 1950s, apparently 527 Mark before the price cuts of the fourth quarter of 1953, and 395 Mark in the last catalogue of 1970 for remaining Exakta stock; Morrison gives $450 in the United States in 1952–53 for the fat version, with a deposit and a wait of months. Neither is a Contax-mount price, and none has been found.

How to tell them apart (expand)

Mounts on the EXTERNAL bayonet with its own focusing ring, like the 8.5cm Sonnar — and unlike every 50mm, which the body's wheel focuses
Chrome over brass and uncoated is the 1940 batch; aluminium with a red T is 1950 or 1954. There is no chrome postwar Contax lens and no aluminium prewar one
Engraved Carl Zeiss Jena, not Zeiss-Opton or Carl Zeiss alone — Oberkochen never made this lens, though it remounted some
A slim barrel with 18 aperture blades. A fat preset barrel with 10 or 12 blades in Contax mount is an SLR lens remounted

Prewar, chrome over brass:

Heavy chrome-over-brass barrel, uncoated, engraved 7,5cm — the only Contax-mount Biotar 75 that is not aluminium

Postwar Jena, first batch (December 1950):

Aluminium barrel, T-coated, red T, engraved Carl Zeiss Jena; the slim barrel with 18 aperture blades, not the fat preset barrel of the SLR lenses
Mounts on the EXTERNAL bayonet with its own focusing helicoid, and couples to the rangefinder

Postwar Jena, second batch (1954):

Still the slim barrel, 18 blades and f/22, on the one 1954 example described — built alongside the fat SLR barrel, not after it

Serial-range notes

the whole number: How to date one. Carl Zeiss drew every photographic lens number from a single running sequence covering all models at once, so a Zeiss lens is dated by reading its number off a serial/year table rather than by counting within its own type — there is no per-model list of the Leitz kind. camera-wiki's table, taken from Wilkinson and Glanfield's A Lens Collector's Vade Mecum, gives the prewar and postwar Jena bands, and Craig Camera publishes a near-identical list.
2678326–2790346: camera-wiki's 1941 band, which is where Pacific Rim Camera's prewar Contax batch of 2759801–2759900 falls. Pacific Rim Camera dates the batch 1940. The bands overlap at their ends (see below), so both can be true; a chrome Contax Biotar 75 is a 1940–41 lens either way.
3000000–5000000: The postwar Jena bands that bracket the aluminium lenses, from camera-wiki: 3,000,000–3,200,000 = 1945–49; 3,200,000–3,470,000 = 1949–52; 3,470,000–4,000,000 = 1952–55; 4,000,000–5,000,000 = 1955–58. Carl Zeiss Jena in the East carried the prewar numbers on from 3,000,000; Carl Zeiss Oberkochen in the West began again at 10,000 in 1946, so a six-figure Zeiss number is an Oberkochen lens of the early 1950s and never one of these.
3467751–3467850: The first postwar batch, if it was numbered in one run of 100 from the opening number that The Lens DB and Morrison give. Two lenses are known inside it: Leitz Auction's Contax-mount no. 3467776, and no. 3467786, which Morrison lists as one of the three Leica-thread lenses. The block sits at the very top of camera-wiki's 1949–52 band, three digits short of the 3,470,000 boundary, which is consistent with a December 1950 batch allotted late in that block. The closing number is this page's arithmetic, not a published figure.
3170182: A Contax-mount lens numbered well BELOW the 1950 opening. Leitz Auction 10 offered no. 3170182 as lot 493, dated 1949 from its number, "in top condition, very rare with the original Contax mount, very early — possibly a lens for testing purposes"; it sold for €2,640 with premium against an estimate of €3,000–4,000. A number in the 1945–49 band predates both of Thiele's batches, which is why the auction house reads it as a test lens rather than a production one. It is the only such example found.
any Contax-mount lens whose number falls in an M42 block: Not necessarily a fake. Roland Bischoff, commenting on Casual Photophile on 4 August 2021, reports that several 1.5/75 Biotars in Contax RF mount have surfaced that were originally built in M42, and that inquiries at Zeiss and with Thiele personally confirmed a number of M42 lenses made in Jena were remounted to Contax RF at Oberkochen — technically possible only from the M42 mount. How many, and when, is not recorded; the comment is the single source for it. Such a lens is a factory remount, and its number will date it to its M42 batch rather than to either Contax batch.
any number near a year boundary: Blocks were allotted to production in sequence, but batches were not always finished in block order, so the published year bands overlap and a serial places a lens within a year or two rather than to a month. Pentacon Six sets out the mechanism and points to Hartmut Thiele's Fabrikationsbuch Photooptik, a transcription of the factory books, for batch-level dates — the book behind the 100 and 125 above, and the one Bischoff dates his examples from.
a letter followed by five digits: Not a lens number at all. That is the Zeiss Ikon CAMERA sequence, inherited from ICA in 1909, which rolls to the next letter at 99,999. A Contax body number and a Zeiss lens number belong to separate schemes and must never be read against the same table.

Specifications

Formula: Biotar — a six-element double Gauss, the design the Sonnars were built to beat
Designed by: Willy Merté — optical design, completed 20 April 1938
Construction: 6 elements / 4 groups
Aperture range: f/1.5
Min. focus: 1.1 m
Weight: 500 g
Filter: 58 mm
Years manufactured: 1940–1954
Country: Germany

What reviewers say

Cheyenne Morrison (Casual Photophile) (blog) — The original "King of Bokeh", shot as a fat-barrel SLR lens: two different looks wide open — at one to two metres it blurs the background like a Monet with only a hint of swirl, and at five metres with dappled light behind the subject the swirl comes into full swing. Not the Contax lens, but the same glass.
The Phoblographer (blog) — On an adapted Sony: "quite literally blown away" by the bokeh; soft outside the centre, as expected of the vintage, which makes it forgiving for portraits, and low enough in contrast to edit easily. An SLR-mount lens, not the Contax one.
Crafting Pixels (blog) — Strong cat's-eye highlights that follow a circle round the centre at f/1.5, subdued by f/2 and gone by f/2.8; superb centre sharpness even wide open, edges and corners adequate. An SLR-mount lens.

History

The 7.5cm f/1.5 Biotar is the Contax lens that was never really a Contax lens. Willy Merté finished the design on 20 April 1938 and Zeiss put it into production in February 1939 for the Kine Exakta, the first 35mm single-lens reflex, and that is where it lived: 10,300 Exakta lenses on Cheyenne Morrison’s count out of 16,827 in all, the rest in the M42 thread of the Contax S and the Praktica, in Praktina mount, and a handful in Leica thread. Marco Kröger, who counts nearly 20,000 over thirty years, adds that they were built in lots of 100 to 300, usually one lot per mount per year, so the lens was hard to get even when it was current. It was the fastest portrait lens made until Leitz answered it with the Summarex in 1943, and the lens Morrison calls the original King of Bokeh.

The Contax rangefinder got it twice, and in tiny numbers both times. Pacific Rim Camera records a single prewar batch of about 100 in 1940, nos. 2759801–2759900, in a heavy chrome-over-brass barrel — a batch no other source mentions, which is why it carries the single-source badge. Then, after the war, the factory books as reported by The Lens DB give 225 lenses in Contax bayonet: 100 in December 1950 and 125 in 1954. Those are postwar East German lenses through and through, aluminium barrel, red T, Carl Zeiss Jena engraving — and, on the one 1954 example described, still the slim 18-blade barrel after the SLR lenses had moved to the fat preset one. Being a long lens it goes on the external bayonet with its own focusing helicoid, like the 8.5cm Sonnar, and couples to the rangefinder.

Two things complicate the postwar count. Leitz Auction has sold a Contax-mount lens numbered 3,170,182, which the Jena serial table puts in 1949, a year before the first batch; the auction house calls it “possibly a lens for testing purposes”, and this page reads it the same way. And Roland Bischoff, in the comments on Morrison’s article, reports on inquiry at Zeiss and with Thiele himself that some M42 lenses built in Jena were later remounted to Contax RF at Oberkochen in the West. A Contax Biotar 75 whose number falls in an M42 block is therefore a factory remount rather than a fake, and there are more genuine Contax-mount lenses in the world than the 225 the books record. How many more, nobody has said; John Keesing’s estimate of about 800, cited second-hand on Rangefinderforum, may be counting some of them.

Why so few? Pacific Rim Camera’s answer is political: by the time the postwar lens was ready, Jena in the East found it hard to sell lenses to Zeiss Ikon and Zeiss Ikon in the West found it hard to buy them, so the lens went where the East German cameras were, into Exakta and M42 mounts. The camera the lens was designed for had also won. The Contax S of 1949 carried the M42 thread the Biotar was already being made in, and the rangefinder Contax was by then the IIa and IIIa, built at Stuttgart while the lens was built at Jena. Two batches, four years apart, and then nothing.

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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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