Carl Zeiss Jena Biotar 5.8cm f2.0

Lens Data

Lens Unit

Lens Photo


min distance : 1m
mount : Leica L39 mount
composition : 4group 6lens
production : around 1941

Lens Impression

このビオターは、5.8cm f2という一眼レフ向けのスペックですが、ライカ・スクリューマウントを持つ非常に珍しい個体です。鏡胴も真鍮製でずっしりと重く、またレンズ先端部を含めた鏡胴のローレットの形態は、従来のビオター5.8cmでは見たことがありません。製造番号から推定すると第二次大戦初期の1941年製と思われますが、戦前型ビオターの鏡胴とも、また戦後数種類作られたどの鏡胴とも一致しません。上の画像にあるように沈胴します。非常に美しいレンズで、所有欲をそそられる出来栄えとなっています。現時点ではマウントが純正なのかどうかはわかりません。

ビオターはカールツァイス社のメルテ(Willy Merte 1889-1948)が1927年に設計した変形ダブルガウス型のレンズです。


メルテは1934年、1936年に続けて一眼レフのエクサクタVP用の80mm f2、キネ・エクサクタ用の58mm f2のビオターを設計します。当時のガラス硝材と設計技術ではダブルガウス型といえども大口径で50mmのまま一眼レフのミラーをクリアするのは難しかったようです。これでダブルガウス型が再び小型カメラ用レンズの主役表舞台に舞い戻ると思われましたが、ここにもメルテの不運な側面が表れてしまいます。時代はそのまま第二次世界大戦に突入。戦後の混乱期に「ビオター」は東独ツァイス・イエナのブランドとなり、徐々にそのブランド価値を低下させてしまいます。西独ツァイス社ではその後、一度は「お蔵入り」となっていた「プラナー」を復活させます。その後の市場競争の結果、現在ではプラナーがダブルガウス型レンズの代名詞となっています。

ビオターの描写は、f1.4の時期と、一眼レフ用に5.8cm f2.0になってからでは大きく変化しています。f1.4レンズは4群6枚でf1.4というやや無理のある設計とコーティングがないことなどから、開放ではフレア気味で周辺には流れも見られますが、非常に緻密で線の細い描写をします。絞ると近代のダブルガウス型との描写の差異が見出しにくいくらいとなります。5.8cmf2では、全体の画質は向上していますが、中央部分の解像精度を上げるためか2線ボケ傾向が強まっており、その輪郭のあるボケが周辺では円周上に流れるいわゆるぐるぐるボケも見られます。

This Biotar has a spec for a SLR camera of 5.8 cm f 2, but is a very unusual individual with a Leica screw mount. The lens barrel is made of brass and feel  heavy which I have never seen such shape of the lens barrel and knurling of the lens tip among other Biotar 5.8cm in the past.  Estimated from the serial number, it seems to be made in 1941at the beginning of the Second World War, but it does not match with the lens barrel of the prewar Biotar, nor with any lens barrel made after the war. It is collapsible as seen in the image above. It is a very beautiful lens, and intriguing possessive desire. At the moment I do not know whether the mount is genuine or not.

Biota has a modified double Gauss type lens designed by Melte (Willy Merte 1889-1948) of Carl Zeiss in 1927.
At the beginning, very fast f1.4 lens for the movie was made , but it was rarely used for still picture cameras.
Merte entered Zeiss in 1913 which was 2 years after Paul Rudolph’s retirement. He worked for lens design under Wanderslep. He worked through in Zeiss company until the end of WWII.
In 1926 which is the previous year of Merte's Biotar, Zeiss Ikon AG was established by merger of several optical companies and Ludwig Bertele of Ernemann entered Zeiss along with Ernostar super-fast asymmetrical type lens and also with the fame of young genius lens designer.

Although Merte and Bertele worked iin the same Zeiss Group, they stayed in separated companies "Zeiss Jena" and "Zeiss Ikon", and the location was also divided into "Jena and Dresden", so direct confrontation might not had happened so often. However, it was unfortunate for designers Melte and Biota that Vanderslep and the Zeiss chose Sonnar in asymmetric design with fewer reflecting surfaces for the next Contax camera but not Biotar in symmetrical with 8 reflecting surfaces in 4 groups 6 lenses.
The double Gauss type had been suffered the era of unfavorable continuation for a while.with a problem of internal reflection and Coma aberration. Double Gauss type lens had been spent its dark days for a rather longer period. Biotar had been produced for Robot camera, Contax, but not many. Double Gauss comes back under spot light after Sonnar lost its general versatility in the age of SLR camera with much longer flange back.. In 1936, "Kine Exacta" which is said to be the first 35 mm single lens reflex was developed. The versatility of single lens reflex has greatly changed the small camera market. Since Sonner had difficulty for adapting SLRs from its structural fate, light comes back to Biotar with symmetrical Double Gauss component again.
Melte designed Biotar of 80 mm f 2 for Exakta VP and 58 mm f 2 for Kine Exakta in 1934 and 1936. It seems that it was difficult also for Double Gauss design to clear the SLR mirror in large aperture of 50mm with the glass material and design technology at that time. Although it seemed that the Double Gauss type would return to the leading position of the lens for the small camera again, the unlucky aspect of Dr.Merte appears here also. The era had entered the Second World War soon. In the post-war chaos period, "Biotar" became the brand of Zeiss Jena in the East Germany and gradually lowering its brand value. In the West Germany, Zeiss, restored "Planar" which had been shelved once. As a result of the subsequent market competition, now Planner became the symbol of the Double Gauss type lenses.
The description of Biotar changed greatly between the time of f1.4 aperture and 5.8cm f2.0 for SLR. The f1.4 shows some flare and flows in peripheral area in full aperture because of its difficult design to accomplish f1.4 with usual 4/6 Double Gauss component, but also shows very fine and thin description. It become almost same as modern Double Gauss expression in closed apterture. The total performance was improved in 5.8cm f2.0, but 2 lines bokeh was increased after the effort to improve the performance of its center area. It increased the swirling bokeh in peripheral area.

  Photos with Biotar 5.8cm f2.0


It shows comformable description with very tender light in old western house. Its 2 lines bokeh does not stand out in close distance, but the bokeh of outside trees through round window indicate the characteristic of this lens.


Flare stands out under the outside light, I think some fog in the lens effects it. Bokeh shows rather stiff, but I can not distinguish its swirling bokeh. I suppose the characteristic of this lens is closer to the earlier type of Biotar with f1.4.