How camera can have more then 525 lines ?

[ak357 0]

Some company advertise cameras have more then 525 lines

Can somebody explain to me please how is it possible ?

I always thought that NTSC is 525 lines of horizontal resolution

Thanks

[rory 0]

Typically High Res Color is

 

450-480TVL

 

[Effective Pixels - Picture Elements]

811 H x 508 V (NTSC)

795 H x 596 V (PAL)

 

Typically High Res B/W is

 

570-600TVL

 

[Effective Pixels - Picture Elements]

811 H x 508 V (EIA)(NTSC)

795 H x 596 V (CCIR)(PAL)

 

Typically True Day Night is

 

450-480TVL Color / 570-600TVL B/W

 

[Effective Pixels - Picture Elements]

811 H x 508 V (NTSC)

795 H x 596 V (PAL)

 

 

Typicall Low-mid Res Color

 

380TVL Color

 

[Effective Pixels - Picture Elements]

542 H x 492 V (NTSC)

542 H x 582 V (PAL)

 

 

lately more and more companies have been producing 520-540TVL color cameras. Typically these are digitally enhanced to that resolution so it will differ from one to the next as far as quality goes. Sanyo has had the 520TVL cameras now for several years, so essentially it is nothing new. Its just cheaper to do the processing now then it was back then.

 

Personally I dont find much of a difference in the quality from the 480 to 540 cameras, but remember quality of the camera's image will also depend on the lighting/glare capabilities, Backlighting (somewhat related) capabilities, Lens/Focus, and overall effective pixels (actual clarity of image). With the Sanyo's I always disable the 520TVL feature anyway.

 

Most of the 540TVL cameras come out of S korea Now from a couple main manufacturers.

 

Look for the Effective/Pixels in the camera's specs though, as thats what really matters. If its a cheap OEM camera its highly unlikely that you will find those specs and more chance that they will not have the effective pixels of a more expensive camera. It will differ.

 

Rory

[ak357 0]

Thx for info Rory

 

but i was talking only about TV lines and nothing else

I still think that to get more then 480 lines is not possible

unless NTSC Standard was change recently and I did not get notified

 

Thanks

[rory 0]

Reason why I posted Pixels also, as if you look at some Cheaper Brands or models, for example the Speco CVC-646HR Mini Dome, which claims 550TVL, they actually give the Pixels in the Specs and they are only 542 (H) x 492 (V), while it should be at least 811 (H) x 508 (V) at 480TVL, let alone 550TVL. So basically it is more like 380TVL (approx). Having used it I can clearly tell it is not even close to 480TVL.

[ak357 0]

Ok

 

lets talk

 

my point is whether camera has 100x100 pixel or 1000x1000

it always produce standard 1 volt peak to peak output

and according to NTSC it can not have more then 480 lines

 

Agree ?

 

p.s. I did not count other 45 lines allocated for vertical blanking etc...

[normicgander 0]

ak357-

 

Don't be confused by the NTSC broadcast standard and CCTV cameras which are compatible with NTSC, but can exceed the 4.2 Mhz bandwidth limitations in NTSc analog broadcast. The NTSC standard has a fixed vertical resolution of 525 lines. However, there are 42 lines (21 per lines field) used for things such vertical blanking, VITS and VIRS, closed captioning etc. This means there are about 484 active vertical scan lines.

 

As for horizontal TVL of resolution, for any camera or system, it's a function of bandwidth mentioned above. There are cameras that have up to 1000 TVL but how would we practically record the signal (bandwidth)any how? (especially with todays low res DVRS)

 

Basically, the increased bandwidth of camera costs alot more money because of the increased complexity of the amplifier circuits in the camera. This includes a high slew rate amplifiers, with fast response times (very low over/undershoot distortion), which allows the video signal to transition from black to white and vice-versa, thus allowing the camera to resolve finer details. This is difference performance between the circuit in a cheesey board camera and broadcast camera. But the board cameras get the job done for the right applications.

 

I did look at the 540 TVL cameras, Bosch, Panasonic, JVC have them. The pixel density on the imagers has increased on the 540 TVL cameras. The bosch LTC 0495 has spec of 752x582 pixels. DSP and improved amplifier design must also play a critical role....

[ak357 0]

Thx Normicganderfor

 

I did not want to get too technical

any DVR or Security capture Card most likely will not have bandwidth

to process high end cameras

[rory 0]

Ak, if you really want to get detailed, here is more information.

 

http://www.maxim-ic.com/appnotes.cfm/appnote_number/750

 

Rory

[Cooperman 0]

ak357,

 

You're right about the getting too technical bit

 

As you probably worked out from normicgander's posting, the resolution (lines) quoted for a camera, relate specifically to lines (or in practice points) that can be resolved along a horizontal scanned line.

 

So the 525 / 625 line (EIAJ / CCIR) scanning system does restrict the maximum available vertical resolution (most cameras are usually in practice around 400 lines vertical), but the horizontal resolution can far exceed this, and in practical terms can be easily tested using a standard test chart and a half decent monitor.

 

Unfortunately in the real world, too often very good quality cameras are fitted with less than ideal lenses, so what may start off as a 540 line box camera, can quickly end up as a 400 ish line c**p camera.

 

Such is life

[blowrabbit 0]

Rory, your really right on about the speco mini-dome. Its the absolute worst dome i have ever installed even though it claims to have a very high resolution. Pulled them all out, really poor.

[rory 0]

Rory, your really right on about the speco mini-dome. Its the absolute worst dome i have ever installed even though it claims to have a very high resolution. Pulled them all out, really poor.

 

Yep, and what sucks is their 636EX bullet camera was a really neat unique product, until they started selling it without Exview ... then it was like all the rest ..

[Soundy 1]

You can always just take analog video out of the equation, and go with something like this:

http://camacc.com/news/VIGIL%20HiDef%20Software%20Announcement.pdf