Archived posting to the Leica Users Group, 2009/06/29
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Natahna, From "LENS VADEMECUM", the more similar I've found is: Tessar Series 1c (1906) f4.5 1.5-20in. Here use 6in for 1/4plate. (Layout Zei 021) There is a hint that the success of the Tessar came as a slight surprise and that the response took a little time in preparing a faster version. Remember that Zeiss introduced the f4.5 Anastigmat, Planar and Unar in succession over some 10 years and may have wanted more continuity at this aperture! The f4.5 Tessar was to be a product which commercially put all of them in the shade. Compared with the f6.3 it was faster and more successful, though connoisseurs say it just is not quite such a charismatic item! But it did replace both the f4.5 Unar and the Planar. Hence the numbering as Series 1c. The designer here was E.Wandersleb. (D.R.P. 142,294).The drawing (Layout Zei.021) shows two flat surfaces. In our experience this is unusual. The rear of glass 1 is more usually concave, as is the inside of the rear pair. But the latter was flat in an early Series 1c f3.5 which was dismantled. Thus Zei022 may be still another variant. The great success of this product means it is one of the easy ones to find and it is still well worth using for black+white work. There are coated examples which might be better for colour. It is normally quite free from flare, but inevitably this tends to affect colour materials more than b+w where it is easy to correct for changes in contrast. In 1914, it was made as 3.0, 3.5, 4.75, 5.25, 6.0, 6.5, 7.0, 8.25, 10, 12, 14, 16, 20in and 16in was suggested for 10x8, and 6in for 5x4in. There may be other sizes, as A. Adams mentions using an 8.5in Tessar in the 1920's. (Autobiography, p60). In view of the later use of interchangable front components, it seems the E. Wanderslab envisaged this as early as 1908-9- but production does not seem to have ocurred. The Tessar quickly became the prestige lens on the bulk of small cameras sold to the general public. This was typically the f4.5 though the f6.3 was also a success. It must have had a major impact on camera design as a result. This is due to the designers in each company having to accommodate the same shutter/lens package and the same rear focus in all the models of the same format. And thence on lens designers whose lenses for sale as alternate fitments now had to conform at least approximately to that of the Zeiss Tessar. Also as the cameras converged, so the identity was lessened, and the possibility of a merger such as occurred to form Zeiss Ikon was eased. But note that this only involved some 4 makers, and the design convergence will have affected firms (such as Ensign in the UK) who were definitely independant. An interesting focal length is the 55mm, found on stereo cameras for 45x107mm format, eg at No471,35x (2x). Another point is that some f4.5/150mm Tessar lenses are in Compound or Compur shutters with oversize rear mounting threads of 44x0.9mm, probably an A size, possibly to allow a bigger rear cell for more even illumination. This is something to note in mounting them as the 44mm ring is now hard to find if missing. An interesting example was marked "Flieger Truppe" at No29587x, possibly a WW1 air lens. During 1999, a group of some 5 Tessars f6.3 and f4.5 were tried out on B+W film 6x9cm using a 1960's coated lens for comparison. There was amazingly little difference between them in contrast for ordinary views outside when shooting at f11 and 1/100sec, and using a lens hood also seemed to be unnecessary. But as the camera was swung to look towards the sun, the difference began to show up, one conclusion being that anything which kept the sunlight off the actual glass was almost equally efffective: so site the camera in shade, even of a telephone pole or hold up a hand, book or newspaper to shade the actual lens. Zeiss seem to have achieved a premium product here, and this may depend partly on the sharpness of the lens image and partly on the careful blacking of the edges and related parts. There are also mentions in older books of the unusual "black" polish Zeiss were able to obtain on the glasses- due to a very perfect surface finish and perhaps an insistence on harder grades of glass. One tentative suggestion is that the choice of polishing compound contributed something to not just the smoothness but to the finished surface layer, which could be modified in refractive index and begin to approach a anti-reflection layer. This will affect (reduce) the reflexions even if not of optimal thickness. On the other hand, maybe you can ask to: http://www.zeisshistorica.org/ where our ancient LUG member Marc James Small is the Vice President: marcsmall at comcast.net Also you can ask to the Yahoo Zeiss Groups, there are really experts: To post a message to this group, send email to ZICG at yahoogroups.com To contact the moderator of this group, send email to ZICG-owner at yahoogroups.com Once you start to investigate the Zeiss history I think is a more passionating history than Leica, Good luck! Saludos cordiales Lluis El 29/06/2009, a las 19:21, Nathan escribi?: > Tessar 1:4.5 f=12 cm Lluis Ripoll luisripoll at telefonica.net http://gallery.leica-users.org/v/luisrq/ http://photo.net/photos/lluisripoll Blog: http://lluisripollphotography.wordpress.com/ http://www.lrmusic.es