Advantage of >480 lines for D-1?

[dbooksta 0]

Given that D-1 only records 480 pixels high what is the advantage (and purpose) of cameras sending a 600 or 650 TVL signal?

[Toaster 0]

That is a great question.... I'm curious to read any response to that too

[GrouchoBoucho 0]

other than weakest-link theory, there isn't one

[ak357 0]

That is a great question.... I'm curious to read any response to that too

 

In past was lots of discussion and "hot"debates about this question

in CCTV forum

[dbooksta 0]

OK, I did some details searching and found the following posts helpful:

 

viewtopic.php?p=196971#p196971

viewtopic.php?p=172618#p172618

viewtopic.php?f=2&t=27302

 

Conclusion: For D1 recording analog resolution above 480 lines is not a relevant spec.

 

And for those wondering why it comes up on IP cameras:

viewtopic.php?f=19&t=26329

[Toaster 0]

OK now I'm confused again.

 

So based on what I'm reading through on those links, am I to understand that any camera 500+tvl is simply buying the spec on paper? and no real difference can be seen or more importantly recorded on D1 ?

 

I know the question of "Whats the best camera" comes up every day... and I'm sure the pro's who are regulars here get tired of seeing those posts, BUT here we go.

 

(SORRY IN ADVANCE FOR THREAD JACKING)

 

So, a couple years ago when I asked that very question, I think the CNB Monalisa chip cameras were one of the favorite inexpensive analog (non-ip megapixel) camera's. And I think KT&D (or KT&C whatever it is) was another inexpensive camera that was posted as being pretty good...

Now I'm getting the impression from lurking through threads that most of the installers have switched to other presumably newer favorite cameras, like the Sony Effio chip cameras. Maybe because of availability, price, performance? I don't know. And to clear this up, CCTV is NOT my "business", I do not install, sell, or anything. I'm a simple consumer asking questions to educate myself only.

 

Now, the simple question here is - what cameras are suggested for D1?

 

Let's assume some knowledge of the basics on the part of the buyer to eliminate some of the obvious questions that will be posted following this.. Varifocal is usually better, because it allows the installer (either pro or consumer), to fine tune the field of view and focus to best suit that cameras application. Some cameras are put up simply to see whats going on in a certain area, while others might need to focus on detail of an area to get a face id, clearly see currency going in or out of a cash register, license plates as a vehicle enters a driveway entrance etc...

 

Fixed lenses can not be focused or zoomed... the lower the mm to wider the field of view. 3.6mm is a pretty popular wide view lens... The trade off is generally speaking a wide view lens provides less fine detail, so facial id is harder on a wider view than on a narrow(er) view. NOT IMPOSSIBLE, JUST DIFFERENT. This is obviously something the buyer needs to know before buying a camera for a specific application.

 

Now, here is where the experts come in. Because CCTV is not our source of income, we are not up to date on bleeding edge tech, specs, etc. WE don't now the difference between CMOS and CCD, MonaLisa DSP vs Effio DSP, S/N ratio, the Sony 760 chip, 960h chip, exview, superhad 1 or superhad 2, etc. That's why we ask the question WHATS THE BEST CAMERA. Without being over analytical.

 

As an example, I'm trying to educate myself because of a recent incident where I captured a vandalism event but was unable to get a positive facial id. Why? My fault, the placement of the camera failed me - it was simply too high up. And like most consumers, I didn't fully understand that until AFTER the fact. Now I'm going to take steps to correct my problem and mount another camera lower that should get a face shot should I have another incident.

 

Now the fun starts for us who are NOT IN THE KNOW.... Let's talk EFFIO since that's what I've personally be researching. Buying a 700tvl Effio camera is not as simple as finding the price you like. Why? Because it apparently depends on SO MANY OTHER FACTORS... What image sensor is it using? Spec's claiming simply "Sony 1/3 CCD" isn't good enough... there are 760 chips, 960 chips, and I'm sure more. And this is just 1 example....

 

So now I'm gathering that a cheaper 500tvl camera will provide the same video to my D1 recorder as a 700tvl camera?

 

WOW.................. Unless you eat, drink, and breathe this stuff - it's SOO hard to try and keep up...........

[ilk 0]

Very true, as with most equipement today, the specification sheet is almost not worth the time spent reading it.

 

The CCTV camera is just one small component in the entire system.

 

Questions such as what is the best camera are like asking what is the best vehicle.

 

Does the questioner require face recognition at 1 mile, a general view of a yard to see how busy the parking spaces are or to see if someone is in the main entrance? Each would require a different camera system.

 

With CCTV the experts know that there are a vast amount of other issues that need to be considered.

 

Risk profile, legislation, position of cameras, the environment, operational requirement, how do you get evidence fromthe system (and can the agencies who receive it decode/display it?), privacy, ease of operation by the end user, total cost of ownership, what media do you use for recording (why use SAS disks instead of SATA?).

 

The results from some of the considerations listed above will then allow the designer to look at the technical issues. Do not jump to the latest thing promoted by marketing departments. We still see analogue system that provide far more effective video than some IP camera systems.

 

In the end you always get what you pay for. Domestic CCTV will at best offer general overviews and are less likely to offer face recognition or licience plate detail (if this is the purpose of the system) than a professionally designed, installed and maintained system.

 

As a specialist in the field I would estimate that around 50% of my surveys will result in me reccomending that CCTV should not be installed as implementation of such a security system is unlikely to meet expectations and/or the budget could be spent on more effective target hardening techniques.

 

Just my thoughts

 

Ilkie

[Securame 0]

D1 on PAL is actually 720x576... So yeah, I can easily spot an advantage on using cameras up to 600tvl

[Horizon 0]

Hi folks.

The tv lines refer to the horizontal resolution, measured across the center three-quarters of the image. The edges are ignored, due to poor focusing from the lens or electron beam (vidicons, CRTs). It allows the line count to appear higher (besides, usually only the center of the image really matters).

http://www.sumasmedia.com/pages/TV-Lines.html - note that the lines shown on the link should be centered on the screen, not off to the left as shown. Sumasmedia doesn't quite undertand the concept!

So the max. resolution of your 704 x 480 pixel 4CIF recorder is limited to about 528 TVL across the screen. The amount of comression used (MP4, H.264, wavelet) can further reduce the effective TVL count, as the compression is lossy - information is lost during compression, resolution degrades.

 

A higher TVL may indicate a higher quality camera, or it could be that the marketing dept. has gotten to the specification sheet.

 

Vertically, each image is made up out of two fields, each measuring 240 lines (pixels), interlaced so one field uses even lines, the other odd lines only.

In television terms, the vertical resolution (number of scanlines) is fixed by the PAL/NTSC standards, and it is only the horizontal resolution that can vary. This depended on the amount of bandwidth allocated to the TV channel, and the quality of the video amplifier in the TV.

[ak357 0]

Hi folks.

The tv lines refer to the horizontal resolution, measured across the center three-quarters of the image. The edges are ignored, due to poor focusing from the lens or electron beam (vidicons, CRTs). It allows the line count to appear higher (besides, usually only the center of the image really matters).

http://www.sumasmedia.com/pages/TV-Lines.html

So the max. resolution of your 704 x 480 pixel 4CIF recorder is limited to about 528 TVL across the screen. The amount of comression used (MP4, H.264, wavelet) can further reduce the effective TVL count, as the compression is lossy - information is lost during compression, resolution degrades.

 

That why long time ago

I create very simple pix to show "some" customers

difference

 

For example

each line are one pix wide

The trick is about positioning.

Camera must see left and right edge of this pix only

then u set DVR for CIF or D1 and record.

Then playback

for some people results can be shocking.

This test does not measure.

Just show total path performace from camera to playback on DVR

[ipvision 0]

Given that D-1 only records 480 pixels high what is the advantage (and purpose) of cameras sending a 600 or 650 TVL signal?

 

That is a great question! I plan on asking this to all my distros to see their answers.