Old Old Sinar

[adrian j schafgans]

I recently accquired a very old 4x5 sinar with Hugo meyer co gurlitz satz plasmat 32/22 f 15,3 cm convertable lens. it has 2 removeable elements/cells I am guessing the cells can be used singularly or in unison depending on the required focal length since I shoot black and white coatings are a non issue does anyone have experience or know about this product? Adrian in San Francisco

[Richard Knoppow]

The Hugo Meyer Plasmat was the original of this type of lens. It was designed by Paul Rudolph, the inventor of the Tessar and Protar lenses. Rudolph lost his fortune during WW-1 and had to come out of retirement. He decided to work for the smaller Meyer firm rather than to go back to Zeiss. The Plasmat is derived from the Dagor by air spacing the inside elements. This gives the designer more degrees of freedom to correct the lens. Most modern LF lenses, enlarging lenses, and copy machine lenses are of the Plasmat type. The drawback is the number of glass-air surfaces which resulted in a fairly flare prone lens before lens coatings became available. This is why this basically excellent design was not popular with lens designers before 1945. Each cell of a Plasmat can be corrected for coma, as is the Convertible Protar, so the performance of the individual cells is pretty good. This is the same design as the old Schneider Convertible Symmar. The first Plasmats had some residual aberrations causing some softness of the image. That led to the Plasmat, suggesting a "plastic" image. The type is capable of extremely good correction however. In my experience the greatest cause of low contrast in old lenses is not lack of anti-reflection coating but rather dirt. Old lenses tend to aquire a sort of haze on the inside surfaces. This cleans off easily with lens or glass cleaner but sometimes the way to open the cell is not obvious. Larger lenses often have threaded back caps. These are easy to remove. Other lenses have front retaining rings. These are removed by a friction tool, a tube the right diameter with some sticky rubbber on one end. It doesn't take much internal haze to result in very poor contrast so cleaning is will worth the effort. This is likely a very good lens.