Bengtsson B, Krakau C E
Acta Ophthalmol (Copenh). 1977 Feb;55(1):123-31. doi: 10.1111/j.1755-3768.1977.tb06101.x.
The imaging system of the Zeiss fundus camera comprises a front lens and a mirror with a central opening in the anterior focus of a camera objective. Focusing is achieved by changing the distance between the film and the camera objective. The principal point of the examined eye is imaged in the central opening of the mirror when the camera is correctly positioned. By applying reasoning current in elementary geometrical optics it was found 1) that both the absolute and the relative magnification depend on the "reduzierte Axenlängenkonvergenz" only, 2) that it is possible to correct the influence of refraction on magnification and 3) that the relation between the camera extension needed to provide sharp pictures and the principal point refraction of the examined eye is linear. The validity and practical importance of those findings as well as transcleral illumination and theoretical resolving power are briefly discussed.
蔡司眼底照相机的成像系统包括一个前透镜和一面镜子，该镜子在相机物镜的前焦点处有一个中心开口。聚焦是通过改变胶片与相机物镜之间的距离来实现的。当相机位置正确时，被检查眼睛的主点成像在镜子的中心开口处。通过运用初等几何光学中的推理，发现：1）绝对放大率和相对放大率都仅取决于“reduzierte Axenlängenkonvergenz”；2）有可能校正折射对放大率的影响；3）获得清晰图像所需的相机延伸与被检查眼睛的主点折射之间的关系是线性的。简要讨论了这些发现的有效性和实际重要性以及经巩膜照明和理论分辨力。
