我认为是取舍
这么认为，主要是来自于Erwin Puts的《Three generations of optical design: Berek, Mandler, Kolsch》这篇文，可以去他的网站找到
这里节选Berek的部分
……he had to accommodate his designs to the limited number of glasses available, and the lack of high refractive glass was quite restricting. If we study the image characteristics of the lenses that have been designed by Berek (most lenses from 1925 to 1948), we recognize this approach. Focal length and aperture are always within the limits of practical design ( a 4.5/135 and a 6.3/28) and when the aperture becomes larger (2/50 or 1.5/85) Berek will accept a slight loss of ‘pure’ performance at the wider openings to allow the overall design to be balanced and deliver harmonious imagery. Berek’s designs and approach were acknowledged in his days, but his accomplishments were not properly valued. In the many handbooks of those period, he is often mentioned, but Merte, Bertele, Tronnier, Lee and others were the opinion leaders……
……when stopping down Berek’s designs performed remarkably well. At the smaller apertures only the central portion of the lens is being used and the small aperture only allows a narrow bundle of light rays. In this area only the primary Seidel aberrations are effectively degrading the image quality. But Berek had a tight grip on these errors and had them very well balanced in the overall design. The resulting performance is very commendable. The well-known atmosphere in the images by Eisenstaedt, Doisneau and many others, this almost velvety depiction of the human condition, the sympathetic and even emphatic rapport between the camera and the subject, is most certainly and decisively influenced by the characteristics of the Berek designs…… 描述一支镜头的设计，可以从目标孔径、对应靶面、色彩还原、分辨率、制造成本等入手，这些因素相互之间有所影响，因此设计者在其中，需要求得平衡。
若是不加以限制的话，可以制造超乎想象的镜头，但实际情况很难允许这样。
我的话，很赞同里面的这个描述：……will accept a slight loss of ‘pure’ performance at the wider openings to allow the overall design to be balanced and deliver harmonious imagery…… 更多的选择整个画面的柔滑阶调，而非大孔径光圈的完美表现
这一点，则是取舍。
然后是Mandler的部分
……Curvature of field was not at the center of the design priorities and to offset this aberration, one had to accept this characteristic. Why CoF was neglected is part of the Leica myth. As a fact we may note that Leitz designs were optimized to finetune the inherent traits of the double-gauss principle…… 对场曲的保留，也是取舍。
至于第三段Kolsch的，我认为，这是在追求完美的光学素质和容易的维修保养中，做取舍。经验来自ASPH的M镜头保养。 |
