The invention contemplates a telephoto-lens construction comprising four parts, one or more of which is a multiple-element part, and so devised as to achieve superior achromatic quality over a wide field of view, within a structural length which is less than the focal length. This result is achieved by following a particular schedule of regions from which to select optical glasses for the respective parts, or for the respective multiple elements of one or more of such parts, and by forming lens elements with such selected glasses in accordance with a particular schedule of refractive powers.
An eye-refractometer includes an objective optic having a first optical path, an apertured mirror for dividing the first optical path into a second optical path and a third optical path, a mask disposed in the second optical path and having linear marks orientated in at least three directions, a radiation source for illuminating the mask, a mask disposed in the third optical path and having liner detecting areas orientated in at least three directions and photocells arranged behind the respective areas. Improvements in this eye-refractometer comprise an apertured plate disposed between the apertured mirror and one of above said masks and an annular apertured plate disposed between said apertured mirror and the other mask. Another improvement is found in that the length of the linear detecting area is shorter than the length of optimum focused images of the linear marks.
An apochromatic wide-angle objective has an improved correction of transverse chromatic aberration while at the same providing a high correction of other errors. These corrections are obtained utilizing long-crown and short-flint glasses.
Optical system for use with attachments for a conventional reflex motion picture camera to permit stereographic cinematography are disclosed. The optical systems include lens systems having four powered elements having negative, positive, negative, and positive focal lengths respectively. The lens systems are adapted to be used with the Bernier stereographic cinematography attachment system as modified for reflex motion cameras. The lens systems include a normal lens system, a wide angle lens system, and a telephoto lens system. The wide angle lens system further includes plane parallel refractive elements to increase its overall length without changing its back focal length, and the telephoto lens system is adapted to be used with internal displacement prisms which bring the images produced by the telephoto lens system into the camera flange opening.
Optical systems for use with attachments for a conventional reflex motion picture camera to permit stereographic cinematography are disclosed. The optical systems include lens systems having four powered elements having negative, positive, negative, and positive focal lengths respectively. The lens systems are adapted to be used with the Bernier stereographic cinematography attachment system as modified for reflex motion cameras. The lens systems include a normal lens system, a wide angle lens system, and a telephoto lens system. The wide angle lens system further includes plane parallel refractive elements to increase its overall length without changing its back focal length, and the telephoto lens system is adapted to be used with internal displacement prisms which bring the images produced by the telephoto lens system into the camera flange opening.
Optical systems for use with attachments for a conventional reflex motion picture camera to permit stereographic cinematography are disclosed. The optical systems include lens systems having four powered elements having negative, positive, negative, and positive focal lengths respectively. The lens systems are adapted to be used with the Bernier stereographic cinematography attachment system as modified for reflex motion cameras. The lens systems include a normal lens system, a wide angle lens system, and a telephoto lens system. The wide angle lens system further includes plane parallel refractive elements to increase its overall length without changing its back focal length, and the telephoto lens system is adapted to be used with internal displacement prisms which bring the images produced by the telephoto lens system into the camera flange opening.
