View Full Version : Number of elements in a lens
I have been using older used lenses, until now. I am ready to buy a new lens but am slightly confused by the selection.
Some lenses are 3-4 elements others are 5-6. Optically is there a difference? I would understand wieght as an issue, but for studio use the optical precision is a higher factor.
According to a not-to-recent Calumet catalog I have the greater the number of el ements a lens the better corrected it is for distortions.
Usually, the angle of coverage dictates the number of elements needed. A long fo cal length lens has a smaller angle of coverage than a short focal length lens f or a given film size. Since longer lenses need a smaller angle of coverage, you dont need many elements to give the needed corrections, where a short lens, with a wide angle, needs more corrections. Many older lenses are tessar types (4 ele ment), with about 55 degrees of good definition. If this covers your film, then it should perform just fine. All things being equal, the fewer elements the bett er, from a flare point of view.
Mike, since each optical surface is used by the designer to correct an aberratio n, it would be safe to buy lenses with more elements. I disagree with the other post that said the angle of view determines the number of elements. The Plasmat design (air spaced Dagor with six elements)has been used for 80mm lenses as well as long focal lengths. SR
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