Optical Format	Actual Sensor Diagonal
1/6 inch	~2.7 mm
1/4 inch	~4 mm
1/3.2 inch	~5.7 mm
1/3 inch	~6 mm
1/2.5 inch	~7.2 mm
1/2 inch	~8 mm
1 inch	~20 mm

Table showing the most common CCD and CMOS formats

 

 

Focal Length

This parameter tells you how far behind the actual plane of a lens an image will form. In addition, it describes the magnification obtained from the lens.

 

A lens featuring a long focal length produces images far behind it's principal plane and high magnifications and narrow fields of view (like a telephoto lens).

 

A lens featuring a short focal length produces images close behind its principal plane and low magnifications and wide fields of view (like a wide-angle lens).

 

For typical imaging systems, the horizontal field of view is 40 to 50 degrees. For most applications, the relationship between the focal length, f, an image sensor dimensional width, w, and the lens/sensor combination’s field of view, θ, is equated as:

Eq. Field of View

 

Here, tan-1 is the trigonometric operation arc-tangent. In this equation, if w is the image sensor’s horizontal width, then θ is the camera system’s horizontal field of view. If w is the image sensor’s diagonal width, then θ is the camera system’s diagonal field of view.

 

Aperture size

This is the focal ratio, the ratio of the optical lens focal length to its diameter. It usually ranges from f/1.4 to f/8. Smaller f-numbers equals larger openings and more light, while larger f-numbers are less dependent on focus adjustments. The amount of light let in by the lens is inversely related to the square of the f-number. As an example, an f/4 lens lets in 16x less light than an f/1 lens. Some lenses feature Auto Iris, meaning that it provides control over the f-number or effective lens diameter.

 

Lens resolution

If an image sensor contains pixels that are, for example, 3 microns wide, then the proper lens to use with that sensor should be able to resolve 5-micron-wide objects on to the sensor. If the lens used can not resolve image features as small as 3 microns, then the images resulting from that particular lens/sensor combination will appear to be blurry. If the lens used resolves image features that are equal to, or smaller than, 3 microns wide, then the resulting images will be sharp.

 

Mounting

Fixed lenses are typically made to mount into a standard mounting ring that surrounds the sensor, and there are several standards. In CMOS and CCD camera systems, C-mount, CS-mount, and S-mount are common mounting thread formats. S-mount works well in designing small cameras, but the small S-mount lenses often have lower light sensitivity compared to C-mount equivalents.

 

Mount	Threads	Comments
C	132	Common in CCTV
CS	132	Common in CCTV
S	M12 x 0.5	Common in compact systems

 

 

Pixavi lens technology

Pixavi is using high end optics and CMOS sensors. Our Xcam, Xcaster and Xcorder series lenses features auto Iris, auto focus and Motorized zoom. Our image pipeline technology features auto white balance, auto Exposure, auto Gain, noise removal and other important features that allows for a high end camera.

 

The Image sensor formats we use is 1/3" 1/2.5" and 1/2" which allows for good low light sensitivity and allows for improved image quality compared to the smaller sensors found in mobile phones etc.