This document discusses lens and image sensor technology for IP cameras. It covers topics such as lens types, focal length, aperture, depth of field, view angle, and how lenses interact with infrared light. It also discusses CMOS vs. CCD sensors, interlaced vs. progressive scanning, and factors that affect image quality such as shutter speed, gain control, denoising, backlight compensation, and lighting conditions. The document provides information on these topics to help understand how camera lenses and sensors work and the key considerations for image quality.
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01 lens & sensor technology 20130123
1. Lens and Image Sensor
Technology
Release department: ICB MKT | AVer Information Inc. | www.aver.com | 2013-01-23
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26. IR Corrected Lens
Since visible light is composed of lights of various wavelengths, with a single
lens, light is bent in the same way as with a prism and the focal lengths of
lights with different wavelengths vary. As a result, not all light rays reach the
same point (focal point), which causes chromatic aberration.
IR Corrected Lens (type of Chromatic Lens)
The purpose is to compensate for the focus shift by
matching the focal lengths of two different
wavelengths (e.g. visible & IR lights) to reduce the
chromatic aberration to a certain extent. However,
lights of other wavelengths have different focal
lengths and result in residual chromatic aberration,
which is known as the secondary spectrum.
image source:
Microscopy Resource Center
27. Extra-low Dispersion (ED) Lens (色散)
Extra-low Dispersion Glass (ED Lens)
It a more a expensive and higher-quality glass that reduces chromatic
aberrations, or optical color defects (fringing) to a remarkable degree thus
helps the lens to always stay in focus. It is most suitable for day & night and
those with telephoto lens IP cameras.
image source: Nikon
32. Progressive Scanning
Progressive scanning (*all IP cameras adopt progressive CMOS cameras)
values are obtained for each pixel on the sensor and image data is scanned
sequentially line by line, producing a full frame image
entire image frame can be sent over a network but requires higher bandwidth
best for presenting moving objects
*720p represents 720 lines progressive; 1080p represents 1080 lines progressive