"Effective pixels" question....

[jamesetherton99 0]

How is it possible for the ¼” CCD to have more “effective pixels” than the larger 1/3” CCD camera. Here are the two cameras I am looking at:

 

 

 

Camera Specifications Model GW648W

Image Sensor 1/3" SONY CCD

Effective Pixel NTSC: 768(H)x494(V)

Sensor area 4.9mm x 3.7mm

Horizontal Resolution 540TV Lines

Minimum Illumination 0.0 Lux (IR LED ON)

Electronic shutter Auto: 1/50(1/60) ~ 1/100,000Sec

S/N Ratio >48dB

Gamma 0.45

Lens 3.6mm

Video Output 1. 0Vp - p, 75Ω

IR wave length 850nm

Power supply DC12V±10%

Power consumption IR Distance

20M (65.6 ft with 24 Unit infrared LED)

 

Camera Specifications Model GW648

 

Image Sensor 1/4" SONY CCD

Effective Pixel NTSC: 811(H)x508(V)

Horizontal Resolution 540TV Lines

S/N Ratio >48dB

Clock Frequency (MHz) NTSC: 19.0699

Scanning System 2:1 Interlace

Minimum Illumination 0.0 Lux (IR LED ON)

Synchronous System Internal, Negative sync.

Auto Electronic Shutter NTSC: 1/60s~1/100,000s

Gamma 0.45

IR Distance 20M (65.6 ft with 24 Unit infrared LED)

IR Status Under 10 Lux by CDS

IR Power On CDS Auto Control

Video Output

1. 0Vp - p, 75Ω

Auto Gain Control Auto

Power/Current DC12V±10%/500mA

Lens 3.6mm

Dimension (mm) 126x69x67

Weight (g) 700

Storage Temperature -30 ~ +60˚C

Operating Temperature -10 ~ +45˚C

 

Also, I notice that when I research the 1/3" CCD camera above, that I get conflicting TVL's on a different website. It tells me 480TVL. Now I am really confused. What's the deal with a particular camera's specs. giving two different TVL specs? Am I being lied to?

 

Thanks.

[jamesetherton99 0]

Well, I did speak to the tech. staff of this camera wholesaler (shoppingcctv.com) and was told that they had an upgrade to all 1/3" CCD's. They then corrected the specs. on the website and list these two cameras as both being 1/3" CCD's and both as being 540 TVL cameras. However, they "effective pixels" are still higher on one camera. I tried to google the exact meaning of "effective pixels" and couldn't really get a satisfactory definition (not being a CCTV camera expert).

 

Can somebody please tell me if the "effective pixel" spec. is something to take into consideration and if I should buy the camera with the most effective pixels, all other specs. being the same?

 

i asked the staff about this, but they really couldn't tell me, saying instead that they "upgraded the CCD's and made the changes" on their website.

 

Thanks.

[yakky 0]

Effective pixels is marketing speak. If its over 500 lines and you are recording in D1, you are probably not going to get anything better using that spec. In fact shopping cameras using line specs is a TERRIBLE idea. I'd rather take a 380 line TDN+WDR camera over the latest cheapo 700 line camera. Regarding CCD size, you can vary the amount of pixels in the same image sensor size, there is no rule saying you have to have a 1/3" sensor to get over 700 lines. The sensor can use smaller or larger pixels. Cellphones have very small sensors and are over 5mp. For more info on that, google "The Megapixel myth" it realates to photography in general but it will clarify the issue for you.

[Toaster 0]

Cellphones have very small sensors and are over 5mp.

 

I never thought of that. " title="Applause" />

 

I will say this, along the same topic, I don't understand how CCTV camera's produce such radically different image quality versus a consumer grade camcorder. Watching CCTV footage from an analog system, then compared to some old home movies from a SD camcorder... wow.. the camcorder is so much better.

[yakky 0]

Cellphones have very small sensors and are over 5mp.

 

I never thought of that. " title="Applause" />

 

I will say this, along the same topic, I don't understand how CCTV camera's produce such radically different image quality versus a consumer grade camcorder. Watching CCTV footage from an analog system, then compared to some old home movies from a SD camcorder... wow.. the camcorder is so much better.

 

Two big factors....

 

Lens quality and image tuning. The camcorder is going to have a much better lens than most cheaper CCTV cams. Second, the image on CCTV systems is usually tuned for wide dynamic range and isn't optimized for pleasing colors.

 

That said, I'll put my QVIS Eye 34's against any old SD camcorder. I have older youtubes shot with a quality Canon camcorder and to me the D1 output from my modern cameras is better as far as general IQ goes.