RB> Helios-40 is Planar-like design, 6 lens/4 groups. Very little RB> difference between 40 and 40-2 (diaphragm preset on 40-2 and 67mm RB> filters - 40 has 66mm).
RB> Early version of Zenitar 85/1.4 was called Helionar 85/1.4, it was RB> M42 screw mount lens. >>The Jupiter 9, another 85/1.5, I have no specs on. RB> Jupiter 9 is 85/2. Still in production - www.lzos.ru. Hi Roman, thanks for the info! Just a very little clarification and some boring technical stuff - I thought so far that the Helios 4 (44) was Sonnar (assymetrical). That was wrong, even though the name hints at Sonnar (Helios - get it? <g>) design. A bad indice. Now I have looked at all the diagrams in detail and together, comparing them directly. All these lenses are Symmetrical, that is Gaussian derivates, not Assymetrical (Triplet > Tessar > Sonnar derivates) like I (and others) first thought. None of the Helioses is Planar design, nor Biometar. They are most closly similar to Leitz Summar (early 50/2 Leitz lens IIRC). But planar-like is of course close enough :) A Helios-4 (probably the earliest Helios 50mm lens? I dunno) is almost a direct copy of the Leitz Summar 50/2 lens. The later, Helios 44(-2) (and some obscure ones like H.-97) are tweaked Summar design (but still the same "type", just different sizes and strengths of elements). Planar and Biometar are somewhat different (one element less, different group split, some inverted elements. They are also older). Confused yet? I am already, let me tell you! What I don't know is history of Biotar. Anybody please :) ? Sorry for the boring technical stuff but I feel that these words (sonnar, planar, gaussian, etc) are being thrown about (and I made a lot of mistakes with these terms! helping the confusion - sorry) a lot without real meaning. Now this post is a result of direct comparison of the diagrams in a technical book of photography from the 70s, and other books, so I hope I got it right this time ;) BTW, the Helios 40 "diagram": 6 el 4 gr. The design of H44 is the same, only the relative sizes and strengths of the elements differ. rear +_+-_-+_+ front (+ pos, - negative elements, _ airspaces) Good light, Frantisek Vlcek - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
