SEIKO LENS Technical
SEIKO LENS Technical
SEIKO LENS Technical Info

F number

¡°F number¡± normally indicates the brightness of lens. A lens is brighter when this number is smaller, and more light can penetrate when shooting in dark.
When using lens with smaller F number (bright lens), whiteout can be prevented by focusing and ND filter because effect of light is reduced to the minimum at a bright place.

Size of field

CCD image size of the camera is closely related to angle field of view. When using smaller image size of CCD, the angle field of view becomes narrower even for the same lens. The camera can be used if the format size of lens satisfies the image size of CCD as shown above.
If it does not satisfy, ¡°shading¡± occurs on the monitor. Shading is a phenomena that the black parts appear on the four corners where the format size does not satisfy the image size of CCD.

C and CS mount

CS mount is generally the mainstream of camera recently. CS mount camera can use both C and CS mount lenses. When using C mount lens for CS mount camera, a CS adapter ring is required. CS mount lens cannot be used for C mount camera.

Standard C mount camera CS mount camera
Flange focus 17.526mm 12.5mm
Diameter of fixing screw U1 32 U1 32

Compatible C mount camera CS mount camera
C mount lens applicable applicable(Adapter is required)
CS mount lens inapplicable applicable

C mount lens/CS mount lens

Auto-Iris Lens and Manual Iris Lens

Auto-iris lens is used for outdoor where brightness changes in day and night. Manual iris lens is used at where a constant brightness can be obtained (mainly indoor).

Depth of Field

Depth of Field means a range of field where the camera can focus.

Day and Night Lens

Resolving Power of Lens in Near-Infrared

Normal lens for monitoring camera has different focal planes due to change of wavelength. Focus difference of DN (day and night) lens is reduced to the minimum between visible light and infrared light.

Video Drive and Direct Drive Types

Video drive type lens has amplifier mounted that transforms video signal from camera into iris control.
Direct drive type lens is operated by amplifier within camera. This lens does not have amplifier mounted.

* It is possible for recent cameras to output in both types.