MODEL CHK -538 Day&night CHK -530 CHK -531 CHK -551 CHK -551B Day&night CHK -551R Day&night,IR Pick-up device 1/4 inch?olid state image sensor Number of pixels PAL:752(H) 582(V) NTSC:768(H) 494(V) PAL:512(H) 582(V) NTSC:512(H) 492(V) Horizontal resoltion 480TV Line 420TV Line Minimum illumination 0.01Lux/F1.2 0.1Lux/F1.2 0.01Lux/F1.2 Lens mount 22x Zoom Lens (3.9-85.8mm, F1.6-3.7) Zoom ratio 220X 22X control RS-422/485 Backlight compensation ON/OFF Electronic shutter NTSC:1/60~1/10,000Sec PAL1/50~1/10,000Sec White balance Auto/Push Auto AGC Auto S/N ratio More Than 48dB (AGC Off) Gamma correction >0.45 Operation temperature -20degree~50degree Sync system Internal/System Video output 1.0v p-p /(75ohm, composite) Power consumption Max, 4.5W/360mA weight(g) 310g Dimension(mm) 60(W) 60.4(H) 103(L)mm