Vivotek NR7401 Manual de usuario descargar pdf (Pagina 20)

Chap.2 Lens and Image Sensor Technology

2.3.2 View Angle

View angle is determined by the focal length of the lens and the sensor size. The shorter the focal length (Figure 2.15)

and the larger the sensor size (Table 2.2), the wider the view angle.

f= 8

f=4

Focal length

Horizontal view angle

Vertical view angle

Diagonal view angle

4 mm 6 mm 8 mm 12 mm

∘

Focal length

Vertical view angle

Horizontal view angle

Diagonal view angle

4 mm 6 mm 8 mm 12 mm

∘

37∘

58∘

33∘

25∘

41∘

25∘

19∘

31∘

17∘

12∘

21∘

(a)

(b)

Figure 2.15 View angle for different focal length with same sensor size

Table 2.2 View angle for different focal length with (a) 1/4” and (b) 1/3” sensors

2.3.3 Day and Night

Infrared light has a different wavelength from visible light, leading to jagged and blurred images. The day and night

functionalitycanreducetheinuenceofinfraredlightonimagequalityandcanbeachievedbyusinganIR-cutlter

removableandIR-corrected lens.Duringthedaytimewithsufcientillumination, infraredlightisblockedtoavoid

color shift. During the night, infrared light can be utilized to enhance cameras’ night vision so as to maintain good

image quality.

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Vivotek NR7401 Manual de usuario Pagina 20