B & W (Walter Biermann and Johannes Weber), Berlin, Germany. They started in Berlin in 1947 making high grade optical filters (color filters) and using Schott glass. They made filters under contract to many (most?) of the leading German firms inc Leica, Hasselblad, Rollei, as well as selling today (2000) under their own name. It is therefore interesting to compare the mounts of some in-house filters and also non-official ones and this explains why they are often so alike. (see advert. Fieldgrass and Gale, Am. Photo. 07/04/2001, p91. Back, F.G. Back (1902-1983) was responsible for a number of developments in early zoom lenses. For 16mm these were available from 1946. His Zoomar Corp. dates from 1951. See especially Voigtlaender for the Zoomar lens. Baker/Baker-Nunn, USA. Specialist makers of high quality aerial survey cameras, initiated at Harvard in WW2 using K22 cameras. Products included first a f5.0 40in lens, then f6.3 60in and f10 100in by 1947. These were thermostatted in use for optimum performance. Later there was a f8.0 144in, for 28x28in in 1960, mirror optics for tracking such as a f1.0 24in and a f4.0 64in. (The layout of the 40in is shown in Bak 001). (See also Polaroid for a J.Baker and W.Plummer designed lens, possibly the same firm.) Balbreck Aine' et Fils, France. Balbreck were licencees for the Cooke triplet, from TTH of Leicester, along with Mssrs Voigtlaender of Germany. Balbreck lenses do not seem to be common, but one has been mentioned as a f16 290mm RR on a Guyard hand-and-stand camera. There was also a Balbreck option on Le Marsouin (Porpoise) stereo from about 1900. We have noted a "Max Balbreck" on a monocular about 7.5x and it may be they were mainly makers of glasses. Judging from FBB they were active about 1890-1920, but often, perhaps always, were listed for RR lenses even in 1920 on the 45x107mm stereo La Francia of Mackenstein. Often as here, they are fitted to Stereo cameras (Jumelles). They do not seem to have made triplets in quantity (one is noted below)but there was a Balbreck lens on a very early Lumiere 35mm Movie camera No130 of 200 initially made in 1895 noted at auction: but by 1900, Cooke lenses from TTH were listed in France by Fournier on a Jumelle and in 1903 by Gaumont on the Block Notes. Users included the Photo Album concealed camera (1890) and several Mackenstein cameras about 1896-1904. A small stereo camera for 40x110mm is shown by Hasbroeck as about 1920, with a pair of 'Rectiligne Balbreck' lenses but with no other engraving. Probably after 1914, the firm was essentially in other fields. One important item noted was a 'Objective Cooke / Brevete HD Taylor SCDG / Ser III 218mm 8.6in (also 13in.) Iris f6.5-f45.// Balbreck Aine et fils / Paris / No497'. This is an impressive brass lens in a Thornton- Pickard shutter and seems to be in imperial thread. Fig 022 004 Balbreck Cooke Series III Triplet f6.5/218mm No497 (with T-P roller blind shutter). 'Balbreck lenses' were noted as a f16 290mm rectilinear on a Guyard hand and stand. This was the first Balbreck noted, surprisingly in view of the note that they were the licencees for the triplet in France. It is likely that the firm was in fact Balbreck Aine et Fils and incompletely listed in the source seen. Balda, Dresden, Germany Primarily a camera maker, their lenses had trade names which reflected their own, as in Baldanar, even though these lenses may have been bought in. Incidentally there was overlap in the Baltar trade name with a Bausch & Lomb movie lens. Examples are: Balda Primar f6.3 105mm This was on a 6x9cm camera about 1928. Baldanar f3.5 50mm This was on a on a 1930's Baldina. Zeconar f2.9 50mm This was on a 1930's Balda camera. Rigonar f3.5 50mm and (f4.5/75mm) on a Mess Rigona, Rigona 35mm and Baldix. Postwar Baltar f2.9 75mm This was on a 6x6cm Baldix, and Super Baldax (1952, 1954, 1956). Baltar f2.9 50mm This was used on the Baldinette and Rangefinder Baldinette about 1950. Baltar f4.5 ?75mm on R/F Baldix 6x6cm. Baldanar f3.5 50mm also on Baldinette. Here the cheapest option was Baldanar, then Baltar and then Radionar f3.5 and f2.9. The Baldinette II used a Color-Isconar f2.8/45mm from ISCO. Baldanar was also used as the entry level lens on the Baldina cameras in 1961, but seems to have phased out to be replaced by ISCO lenses, such as Color Isconar and Color Westanar f2.8/45mm. Color Baldanar f2.8 45mm on Baldessa 1a and 1b. Here Color Isconar was the low price option. Baldar f9.0 72mm on 6x6 Baldixette, about 1960. Baldanon f2.8 38mm on Balda C-35 - a late camera. Baldanar f5.6 38mm as above on Balda C-35, Baldanar f3.5 50mm noted as coated and on R/F Baldina (B.J.A. 1954, p189). Rigonar f4.5 ?75mm for 6x6cm on Baldix 6x6 (1956) and Rigonar f3.5 50mm? noted on Baldinette 35mm in 1954 (B.J.A. p526). Baltar f4.5 ?75mm same, see B.J.A. 1956, p561 Advert. [Ennagon from Enna, f3.5, f3.9 on Baldix. The following are probably related items. Max Baldaweg, Dresden, German. Balda Werk, Dresden, Germany. Among their 1930's lenses were a series probably bought in but of unknown make. Vidanar f4.5 50mm on Picochic 3x4cm Vidanar f3.5 50mm Vidanar f2.9 50mm on 35mm Baldas about 1936, 1934. Also on 3x4cm Picochic. Juwellar Anastigmat f6.3/105mm on Juwella rollfilm Juwellar Anastigmat f4.5/105mm on Juwella, about mid-1930's. Balham Optics, 6, Weir Rd., London SW12-0NA. They are more correctly named Optical Instruments (Balham) Ltd. of Unit 39, Neville Court, Neville Road, Croydon, Surrey CR0-2DS They are repairers and makers of lenses, active currently. Balsam Where glass components are in contact, a sticky clear layer is used to join them- both to keep them aligned and also to reduce light reflexion at the surfaces. The traditional material was from the gummy Canada Balsam of Canadian tree Abies balsamea Miller, though other pines such as Oregon Balsam from Pseuda- Tsuga trifolia are known but are less good. Crude balsam is a mixture and is first heated to 200°C, or to about 130°C in vacuum of 10mm Hg, to drive off light ends as turpentines, and the remainder called balsam, varies in viscosity with how hard (time and temperature) it was heated. Purification and treatment is described in F. Twyman, "Prism and Lens Making", p238. If the balsam is a soft one, the glasses were then balsamed together by warming them by putting a droplet on one, and the mating lens placed on and pressed down with a slight turning movement- pressing till the excess squeezes out and the edges of the glasses are lined up- more stringent alignement ["centering"] will often be needed on a optical test rig. The pair of glasses is then placed in an oven at 77°C for 60hours, and allowed to cool. This bakes light ends out of the balsam at the edges but leaves the centre little changed so that after cooling the glasses stay aligned and together. A harder balsam requires hotter glass before mating the glasses but the final treatment is shorter, say 2 hours at 40°C, as there is no need to bake out the light ends. Slightly different techniques were used in UK, Germany and other places, and factories also varied. Thus different makes have in the long term shown different amounts of balsam failure and this probably corresponds to the hardness of the balsams used and the care taken in annealing. [Thus this text notes elsewhere cases where one product goes yellow and fails partially while others from the same maker stay in excellent condition. Traill Taylor attributes this to assembly into the cell before the balsam has had time to harden, so it is affected by reaction with the brass cell wall]. However some lenses had to be assembled using soft balsam since they were large, subject to temperature changes and had glasses of differing thermal expansion. Typical examples were aerial lenses. One example is the Aero Ektars, where the f2.5/12in (c.120mm dia.) seems to be very subject now to balsam bubbles. There may be no complete answer to this situation. An early case was the Ross-Collen lens, where castor oil was used as balsam- and probably renewed regularly as it did not harden and leaked out. An exception to the use of balsam was when in Germany surfaces were contacted direct and if clean and accurate to 1/2 ring or better, when no balsam was needed. [It may not have been applied to photographic equipment however.] This underlines German difficulties with balsam supplies in wartime, but synthetic balsams were normally the answer and their chemists were adept at seeking such ersatz materials. In his 1952 Edition, Twyman mentions n-butyl methacrylate (H.T. Cement) as the one with suitable properties. (idem, p242) Apparently the monomer is applied, or a siropy mix of monomer and polymer and the glasses united and baked in an oven for eg. 16hours at 60°C when the are united by the clear new layer of plastic formed. Such synthetic balsams are excellent as they are clearer and more consistent, but can have problems.