Angle of view
In case focusing to far, Angle of view means the angle for imaging of the horizontal and vertical in image size. W=2tan-1(Φ/2*f)
In theory, spherical lens never focus into one point on optic axis. By improving the geometry of spherical lens , Aspherical lens realize to focus into one point.
The length from vertex of last lens to focal point. In case too short of bach focus raise to interfere filter in camera.
As M.O.D. of the ordinary zoom lens is over 1m, in case the demanded object distance is under 1m, close-up lens solve the problem.
Coating is for contoling of reflection of ray at surface of lens. Under vaccum, MgF2 is heated up by electric beam and coat on the lens.
The flange back is 17.526 mm
The refractive index is different from according to the wave length. The Chromatic aberration occur by it.
There are 2 kinds of the cromatic aberration, one is Longitudinal chromatic aberration, other is Lateral chromatic aberration.
The flange back is 12.5 mm
Ray has the characteristic features that sneak aroud to behind of Iris. Then blurring occurs when the iris become to small.
real image point is off from the ideal image point because of aberration. The budget means distortion.
One of the way of Auto-Iris. Best bightness will be kept automatically by Iris control signal from camera.
Day & Night lens
The focal point of visible ray and IR ray are not same position. Therefore even if adjustment focus under visible ray, the focal point dose shift under IR ray.
Depth of field
Even if under out of focus, in range that it is not found as out of focus, it is regarded in focus. Such this range means Depth of field.
Extra low Dispersion Glass. Ordinary glass disperse its color according to the wave length but ED Glass can inhibit to the dispersion.
Extender is one of rear conversion lens. It makes the focal length of master lens long. In case of 2 x Extender, the focal length become 2 times but F No. drops 2 stops. It means that the brightness become 1/4.
F NO. means the brightness of the lens. Small F NO. is bright lens. F NO. = f/D
Fish eye Lens
The lens which angle of view is 180 degrees. Like fish eye is called Fisheye Lens. There is shading at the corner of monitor.
When palallel ray is entered into lens, there is a point that the ray gather into one point on optical axis.
It means focal point.
The distance from center of lens to the focal point.
Phonomenon that becoming out of focus under IR ray although focused under visible ray. Because of the difference focus point under visible ray and IR ray.
The length from reference point of mounting lens to focal point.
Function of lens that bring into focus.
Ray reflect inside lens or on face of sensor and the image that is different from fact appear on the monitor.
IR Cut Filter
IR Cut Filter shadow IR light.
Diaphragm of lens. Mechanism for adjustment for brightness of image.
For adjustment for brightness, Iris be controled into open or close.
The image formation of lens is circle. 1": 12.8 x 9.6 mm (16φ), 2/3": 8.8 x 6.6 mm (11φ), 1/2": 6.4 x 4.8 mm (8φ), 1/3": 4.8 x 3.6 mm (6φ）
Lateral chromatic aberration
Refractive index is different from by wave length and in case of becoming longitudinal chromatic aberration big,
the image of color blur.
Longitudinal chromatic aberration
IR Cut Filter shadow IR light.
The rate of brightness of corner compared with center means vignetting.
Minimum Object distance. Within M.O.D., the focus cannot adjust.
Modulation Transfer Function. The recall rate of contrast.
The part which fix with lens and camera.
Ordinary lens is designed its resolution for 400,000 pixel sensor. Megapixel lens is designed for over 1,000,000 pixel cameras. The resolution is quite diferent.
Resolution is one of performance of image formation. When imaging test chart, confirming how lens resolution can perform.
After ray enter lens, the angle of pass means Refraction index.
Vari Focal Lens is a small and conpetitive lens and able to adjust its focal length. But every time focal length is changed, focus adjustment should be neccesarry.
One of the way of Auto-Iris. There is an electric eye circuit board inside lens and be supplied video signal from camera, best bightness should be keeped automatically.
Zoom is able to keep the focus during changing the focal length.
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