A video imaging system is provided. The video imaging system is configured to maintain a video image displayed on a display unit in a predetermined orientation based upon a use. The video imaging system includes an endoscope, a camera head unit, a camera control unit configured to determine a focal distance, and a display control unit. The display control unit is configured to process the focal distance to determine a use. The use is processed by the display control unit so as to maintain the video image in the predetermined orientation. The contextual information may be focal distance, image data or endoscopic orientation.

The objective optical system includes in order from an object side, a first unit having a positive refractive power, a second unit having a negative refractive power, and a third unit having a positive refractive power, and focusing is carried out by moving the second unit, the first unit and the third unit are fixed at the time of focusing, and the first unit G1 includes in order from the object side, a negative lens L1, one of a positive lens and a cemented lens, and a positive lens, and the third unit includes a positive lens, and a cemented lens of a positive lens and a negative lens, and the objective optical system satisfies the following conditional expression (3)
−20<f.sub.2/f<−5  (3) where, f.sub.2 denotes a focal length of the second unit, and f denotes a focal length of the overall objective optical system in a normal observation state.

A large incident angle of an off-axis principal ray is ensured while a stroke of a moving lens group is kept long, and a size is reduced while a focusing operation in magnification is easy.

A magnifying endoscope optical system provided with a negative single lens cemented to an image pickup device and a moving lens group, capable of switching at least between a normal observation state and a proximity magnifying state can be made by moving the moving lens groups; and the following conditional expression (1) is satisfied:

−65<fr/fw<−2  (1) where reference character fr denotes a focal distance of the negative lens cemented to the image pickup device, and reference character fw denotes a focal distance of the entire system in the normal observation state (wide angle end).

An adaptor including: first and second optical systems; a prism comprising a mirror region, first light flux and second light flux from the respective optical systems, being incident on the prism, the light flux passing through the prism at a portion, the second light flux being reflected by a mirror region after passing through the portion, the light flux emitted from the prism to a region; and a light-shield at the region, the light-shield shields one of the first and second light flux and is disposed proximally to the prism relative to an imaging system of the endoscope when the adaptor is attached to an endoscope; the first optical system is disposed such that the first light flux is incident in a direction parallel to an optical axis, the second optical system is disposed so that the second light flux is incident in a direction orthogonal to the optical axis.

A camera head for inspecting pipes or cavities including an array of two or more imaging elements with overlapping Fields of View (FOV) is disclosed. The camera head may include one or more light source elements, such as LEDs, for providing illumination in dimly lit inspection sites, such as the interior of underground pipes. The imaging elements and LEDs may be used in conjunction with a remote display device, such as an LCD panel of a camera control unit (CCU) or monitor in proximity to an operator, to display the interior of a pipe or other cavity.

A five-surface wide field-of view compound lens incudes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a first biplanar substrate, and a second biplanar substrate. The first lens is plano-concave; the second, the third lens, and the fourth lens are plano-convex; the fifth lens is a plano-gull-wing lens. The first biplanar substrate is between the second lens and the third lens. The second biplanar substrate is between the fourth lens and the fifth lens. The first lens has a first Abbe number. The second lens has a second Abbe number less than the first Abbe number. A camera module includes the five-surface wide FOV compound lens and a glass substrate having a planar surface adjoining a first planar surface of the first lens, the first lens being between the glass substrate and the second lens.

There is provided a small-sized and bright objective optical system for endoscope with a wide angle of view and thin diameter, which enables to achieve a highly-defined image.

The objective optical system for endoscope includes in order from an object side: a front lens group having a negative refractive power as a whole, an aperture stop; and a rear lens group having a positive refractive power as a whole, wherein the front lens group includes in order from the object side, a first lens which is a single lens having a negative refractive power and a second lens which is a single lens having a positive refractive power, and the rear lens group includes a third lens which is a single lens having a positive refractive power and a cemented lens of a fourth lens having a positive refractive power and a fifth lens having a negative refractive power, and an object-side surface of the first lens is a flat surface, and the second lens has a meniscus shape having a convex surface directed toward an image side, and the third lens has a biconvex shape, and the objective optical system for endoscope satisfies the following conditional expressions (1) and (2)

−2.0≦f.sub.1/Ih≦−1.39  (1)

−0.2≦SF.sub.3≦0.61  (2) where, f.sub.1 denotes a focal length of the first lens, Ih denotes the maximum image height of the objective optical system for endoscope, and SF.sub.3 denotes a shape factor which is expressed by SF.sub.3=(R.sub.3L+R.sub.3R)/(R.sub.3L−R.sub.3R), when a radius of curvature of an object-side surface of the third lens is let to be R.sub.3L and a radius of curvature of an image-side surface of the third lens is lens to be R.sub.3R.

A deflection prism assembly for an endoscope having a lateral viewing direction, the deflection prism assembly including: a prism holder; and a deflection prism accommodated in the prism holder; wherein the deflection prism has a light outlet surface and an opposite light inlet surface arranged obliquely to the light outlet surface, the deflection prism further having a lateral surface extending between the light inlet surface and the light outlet surface; and the prism holder accommodates the deflection prism such that the prism holder surrounds less than all regions of the lateral surface of the deflection prism.

A rigid-scope optical system includes: an image-formation optical system that causes an image in each of wavelength bands to be formed in a predetermined imaging device, the wavelength bands including a fluorescence wavelength band and a visible light wavelength band; and a color-separation-prism optical system having a dichroic film that separates an optical path of light to be imaged into an optical path of the visible light wavelength band and an optical path of the fluorescence wavelength band, in which the image-formation optical system causes the respective images to be formed in a fluorescence imaging device and a visible light imaging device, the fluorescence imaging device and the visible light imaging device being disposed to cause an amount of misalignment to correspond to a difference between an optical path length of fluorescence and an optical path length of visible light.

There is provided an image pickup unit which is capable of achieving a focused image of a favorable depth of field while changing a visual field direction of observation.

An image pickup unit, comprises a front group which includes a prism that can be rotated for changing a visual field direction, and a rear group which includes a lens group and an image pickup element, wherein the image pickup unit includes a prism rotating section which rotates the prism for changing the visual field direction, and a focusing section which does not change a focused range, as an angle of visual field direction with respect to a longitudinal direction of the image pickup unit becomes smaller than a specific angle, and which moves the focused range toward a near-point side, as an angle of visual field direction with respect to the longitudinal direction of the image pickup unit becomes larger than the specific angle, in accordance with a rotation of the prism, and the focusing section, in a case in which the specific angle is not smaller than 30°, moves the focused range toward the near-point side.