Showing papers on "Depth of focus published in 1984"

Ultra-short optical system for binoculars

Abstract: An ultra-short and novel optical system, designed for the binocular described in U.S. Pat. No. 4,488,790, granted Dec. 18, 1984, having an air-spaced objective that is as short as is physically possible and an Erfle type eyepiece that is also as short as is physically possible, to produce a magnification of 7 power in a binocular with an objective 30 mm in diameter and an eyepiece with a real angle of 9°. A feature of this optical system is the employment of oval mirrors of four different sizes, arranged so that the end mirrors are virtually touching the adjacent lens elements of the objective and eyepiece. Another feature is that the focal plane is curved rather than flat as in conventional binoculars. A further feature is that the first and last achromats of the eyepiece are tilted very slightly at the top in the direction of the objective to elongate the apparent depth of focus by arraying sharp focus along a gradient in the field of view from top (distant) to bottom (near). A final novel feature is the use of "velvet" lining on the inner walls of the tubes exactly enclosing the optical system to absorb off-axis stray light and eliminate glare.

3-dimensional image pickup element

Abstract: PURPOSE:To obtain easily plural pictures having different distances from an image pickup system of a subject for image pickup, by laminating the photo receptor areas of an image sensor at positions outside the forming positions of photoreceptors of another image sensor and opposite to each other CONSTITUTION:The photodetecting areas of laminated photoconductive image sensors 1a-1d pick up the light supplied via a transparent window part of a transparent substrate 2, ie, the image of a subject for image pickup formed via a lens Then the image signals picked up by the sensors 1a-1d are read out in parallel With such a 2-dimensional image pickup element, the matters at different focal positions are formed simultaneously to the sensors 1a-1d respectively according to distances la-ld between a lens 11 having small depth of focus and the image pickup faces of the sensors 1a-1d respectively by providing said image pickup element on the image forming face of an image pickup optical system using the lens 11

Optical apparatus for producing a visual stereoscopic image

Abstract: In the image-side beam path of an objective lens are roof-like mirrors for pupil separation. The two beams pass to a mirror means where the two beams are directed on to an intermediate image plane by pivotal mirrors. The two optical axes cross in the intermediate image plane. In the region of the intermediate image plane is a field lens which feeds the beams to the eyes by way of a beam exit lens. That arrangement provides a stereoscopic image with large depth of focus. The exit pupils are larger than those of the eyes so that the viewer has a certain range of possible movement.

Focusing state checker

Abstract: PURPOSE:To enable easy checking of whether the image-forming position of a desired object part except the object to be focused is within the depth of focus or not by providing a means for checking and displaying the depth of focus corresponding to an aperture for photographing in response with the decision on focusing. CONSTITUTION:The 2nd discriminating circuit 108 for a focusing state starts operation when the image-forming position arrives within a focusing region and a motor (MO) is stopped by the 1st discriminating circuit 107 for the focusing state. When the direction of a camera is changed to the desired part of the object except the object to be focused in this state, the data on the defocusing quantity and direction relating to the desired part is outputted from a signal processing circuit 106. The circuit 108 compares the data on the depth of focus of the width corresponding to the aperture for photographing given from an output circuit 105 for aperture data and the data on the defocusing quantity relating to the desired part and displays whether the result is within the depth of focus corresponding to the aperture for photographing on a display circuit 109 for the depth of focus. The discrimination and display of the depth of focus are accomplished at every direction of the camera toward the desired part of the object.

Optical apparatus for generating a stereoscopic visual image

Abstract: not available for EP0140836Abstract of corresponding document: US4671628In the image-side beam path of an objective lens are roof-like mirrors for pupil separation. The two beams pass to a mirror means where the two beams are directed on to an intermediate image plane by pivotal mirrors. The two optical axes cross in the intermediate image plane. In the region of the intermediate image plane is a field lens which feeds the beams to the eyes by way of a beam exit lens. That arrangement provides a stereoscopic image with large depth of focus. The exit pupils are larger than those of the eyes so that the viewer has a certain range of possible movement.

Detector for imaging state

Abstract: PURPOSE:To obviate a change in the range where focusing is approved even if the luminance distribution of an object, the F value of a lens, etc. change, by comparing three sets of photodetected outputs corresponding to different depths of focus. CONSTITUTION:Three line sensors 5a-5c are so disposed that the limit point N where focusing on a front focus side is approved and the limit point F where the focusing on a rear focus side is approved are positioned respectively at the intermediate of the sensors 5a and 5b and at the intermediate of 5b and 5c. The photodetected outputs of the sensors 5b and 5a are compared in a comparator 13 and the photodetected outputs of the sensors 5b and 5c in a comparator 14. Gates 17-19 are controlled by the results of the comparison, the results of the comparison through inverters 15, 16, etc., and the respective imaging states such as within the range where the focusing is approved, too shallow depth of focus and too deep depth of focus are displayed by LEDs 7c, 7a, 7b. Even if the luminance distribution of the object, the full aperture F value of the lens used, etc. change, the change in the range where the focusing is approved is obviated and the arithmetic circuit is simplified.

Method for mixed-light exposure in still cameras

Abstract: A method for mixed-light exposure in still cameras with built-in flashguns is specified, each photograph being taken using flashlight. The exposure is performed in two stages, flash exposure being performed in a first stage with a small camera aperture and exposure with environmental light subsequently being performed during one and the same photograph in a second exposure stage with a larger camera aperture. In the case of the smaller camera aperture, the depth of focus extends as far as into the near zone, so that the near zone, in particular, is sharply imaged by the flash exposure, and this also has a particularly advantageous effect with interior photographs. The larger camera aperture further provides a sufficiently short shutter speed for imaging the picture background by means of the ambient light.