420, 480, and 540TVL

[Ubon94 0]

Ok, I'm sure a lot of you guys may have explained on this topic before.

 

I'm still not clear on this camera spec because a lot of website listed that spec differently

 

I have seen a lot of website store posting spec of.

 

480TVL camera

NTSC: 510 x 492

 

Now, usually this NTSC line is on 420 tvl cameras..

 

Are there rules that you guys goes by when looking at camera specs..

 

420tvl 510x492

540tvl 768 x 494

 

?

 

I know it's more complex than a TVL..lens, ccd add on features etc..

but i want to keep the topic on TVL

 

Thanks

[CameraGimp 0]

I've just read my post and my answer is a clear as mud! It is however about a clear as I can make it and I think it is right.

 

It is no longer possible to read the number of pixels and guess a cameras resolution as the electronics now play a part. A 470TVL colour camera uses the same CCD as a 520TVL camera.

 

Conventional PAL and NTSC CCD pixels numbers have been set in stone for as long as I can remember and there are two of them (well four due to PAL and NTSC). Here they are:

 

HR NTSC

Number of effective pixels: 768 (H) × 494 (V) approx. 380K pixels

Total number of pixels: 811 (H) × 508 (V) approx. 410K pixels

HR NTSC

Number of effective pixels: 510 (H) × 492 (V) approx. 250K pixels

Total number of pixels: 537 (H) × 505 (V) approx. 270K pixels

 

HR PAL

Number of effective pixels: 752 (H) × 582 (V) approx. 440K pixels

Total number of pixels: 795 (H) × 596 (V) approx. 470K pixels

MR PAL

Number of effective pixels: 500 (H) × 582 (V) approx. 290K pixels

Total number of pixels: 537 (H) × 597 (V) approx. 320K pixels

 

It is probably worth noting that a HR colour CCD has the same number of pixels as a HR monochrome and there is no difference between 1/3" and 1/2", just bigger pixels.

 

So CCD resolutions haven't changed but some colour cameras have moved from 470 to 520TVL. How did that happen? Something to do with the DSP. So now you can't use pixels to relate to TVL. It was a lot easier 5 years a go.