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Xem bản đầy đủ : Camera quan sát hồng ngoiạ là gì



lehaicamera
11-17-2012, 09:01 AM
1) Camera Day/Night: true Day/Night

Loai Camera nay co ten goi la “Day - Night” camera, dung duoc cho ca ban ngay va ban dem.
Va khi chu y den thong so, “Minimum Illumination” thi ta se thay la o che do Color va B/W, 2 chi so min. lux nay khac nhau kha xa.

Vi du: WV-CW380
Min. Lux
- Colour: 0.65 lux
- B/W: 0.09 lux

So di co dieu nay vi truoc thau kinh cua Camera, co 1 tam IR filter. Doi voi loai Camera Day-Night, thi khi chuyen tu dieu kien sang tot, sang dieu sang cuc kem thi tam IR filter nay se duoc tu dong removed ra khoi vi tri nam truoc thau kinh. Vi khong co IR filter, thi Camera moi co the bat duoc cac so’ng IR va nhin trong bong dem duoi dieu kien thuong,lap dat camera quan sat gia re (http://www.vatgia.com/raovat/3974/3832549/lap-dat-camera-quan-sat-gia-re.html)

Chinh vi che do remove filter nay, ma khi chuyen tu “Sa’ng” sang “To’i”, doi voi Camera Day-Night, em se nghe thay mot am thanh “la.o xa.o” nhe. Do la boi vi Camera tu dong remove filter.

2) Camera Day/Night: not true Day/Night

Loai nay goi la “not true Day/Night”. Mot dac diem de nhan thay la thong so “Minimum Illumination” cho dieu kien Colour va B/W cua Camera la kha giong nhau, na na’ nhau. Chinh vi the ma trong Catalogue cua Panasonic, Camera loai nay khi nhac den “Minimum Illumination” thuong duoc gop chung cho ca 2 loai Colour va B/W

Vi du: WV-CF324, cung la Day/Night Camera, nhung khong phai la Day/Night thuc su, tuc khong phai la true Day/Night.
Min. Lux
- 0.9 lux (hieu la 0.9 lux la min. illumination cho ca Colour va B/W) lap dat camera quan sat (http://www.vatgia.com/raovat/7618/5710914/lap-dat-camera-quan-sat.html)

So di co dieu nay la vi doi voi Camera nay, no cung co 1 tam IR filter truoc thau kinh. Nhung khi dieu kien sang chuyen tu “Sa’ng” (Colour) sang “To’i” (B/W) thi tam IR filter nay khong duoc remove di. Tam IR filter nay van nam truoc thau kinh. Chinh vi the no ca?n het cac buoc song ngan, song IR. Vi the ma no can dieu kien min. lux phai cao, chu khong thap nhu loai “true Day/Night”.

Doi voi loai Camera nay, neu co dung nguon IR chieu sang, thi cung vo nghia, vo tac dung. Boi vi tam IR filter van nam truoc thau kinh va chan het cac buoc song IR.

Tai sao trong dieu kien “To’i” thi Camera loai nay van cho ra hinh anh Black and White? La vi che do anh cua Camera chi don gian duoc chuyen het sang B/W, giong nhu “convert picture colour into B/W mode”.

Chat luong hinh anh cua “not true Day/Night” camera kem hon “true Day/Night” rat nhieu. Co nhieu digital noise trong picture.

Tren thi truong, co rat nhieu nhan hieu tuyen bo rang ho co Day/Night Cameras, vi du nhu tu Korea, Taiwan, nhung thuong da so cac loai Day/Night cameras nay la loai “not true Day/Night” ma anh noi o tren. Chat luong hinh anh kem.Lap dat camera gia re (http://cameratphcm.com/chi-tiet-hoi-dap/501-lap-dat-camera-gia-re.html)

3) Camera Hong Ngoai:

Nguoi ta thuong goi la IR Camera (Infra-red Camera). Loai Camera nay co 2 loai.

1 la Camera thuong nhu anh noi o tren, gan them 1 thiet bi phat ra song hong ngoai (IR). Nham tao ra cac buoc song/do sang toi thieu de Camera co the nhin duoc vao ban dem. Chu y la neu dung Camera “not true Day/Night” thi dung them thiet bi hong ngoai la vo tac dung, vo y nghia, vi tam IR filter truoc thau kinh cua Camera khong duoc bo di, khi doi che do sang. Vi the ma tat ca cac buoc song hong ngoai deu bi chan lai boi Filter nay, va do do, khong co y nghia gi trong viec “nhin ban dem tot hon”.

Loai thu 2 la loai co gan san thiet bi Hong Ngoai vao Camera, khong phai la thiet bi Hong Ngoai ro`i nhu da noi o tren.

Tom lai Camera Hong Ngoai chi la Camera thuong, duoc su dung cung voi thiet bi chieu sang ra cac buoc song Hong Ngoai ma mat thuong khong nhin thay. Nhung cac thiet bi ghi nhan Video thi van co the ghi nhan duoc buoc song nay, van co the thay duoc hinh anh (picture),camera quan sat gia re (http://www.vatgia.com/raovat/3974/3924293/camera-quan-sat-gia-re-%7C-camera-quan-sat-gia-re.html).

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