Can anyone give me advice on CCTV camera 'specifications'?

jimbojr · Post by **jimbojr** » Thu Nov 15, 2007 7:24 pm

Hi All,

I'm looking to finish developing my home CCTV system, (thus far I have a cheap generic BT878 capture card from ebay, and have installed zoneminder on Ubuntu Gutsy and it is working with a cheapo CCTV cam also off ebay...)

So I bought a cheap IR day/night cam from ebay to play with and get ZM working with, but would really like advice on better cameras, and what the different specifications mean?

The most confusing is the number of 'lines' of the sensor, and how that maps to the capture resolution? E.g. given a '520 tv line' camera outputting PAL (720x486), does the higher 'lines' simply mean the sensor image is better quality? It seems odd that the # of lines doesn't match the PAL vertical height.....?
When you program the Bt878 to capture at a specific resolution, e.g. 320x240, does it capture all the camera data and then downsize (filter) the image? - or somehow skip input lines from the camera...?

Another question is that most cheap cameras have lots of IR LEDs to illuminate at night, but do 'professional' cameras use these? I don't recall seeing LEDs on the CCTV cameras around the office I work at...

Any other general advice on cameras would be great!! I'd like to make sure I spend enough money to get reliable decent cameras, but not overspend on something that I don't need!

Any advice / demystification on this suff greatly appreciated!!

jameswilson · Post by **jameswilson** » Thu Nov 15, 2007 9:31 pm

ill try

Specs cannot be used alone to decide on a camera. Ore with anything. With cams especially you get what you pay for, you can buy one for £20 or £2000. Odds on the £20 will be poor.

But basically the higher the res the better (stick to tvl ignore sensor size for pal tye cams) and the lower light without gain the better. 1/2" chips perform better than 1/4 cos the need 4 times as much light.

Any of the bullet cam specs needs to be taken with large spades of salt. Go for a branded one every time. (IMHO)

No pro cameras do not put the ir emmitter on the cam, its a bad bad idea for many reasons but its cheap. Proper cams use a seperate emitter but these can cost from £100 to £500 depending on lens and power etc. Most people just use the led ones but personally i hate them (but i have one at home.... i fell for the theory too lol)

Id say on a budget that non ir bullets are great and then use a sepertae emmiter or security flood light. If using IR it needs to be done right.

Lee Sharp · Post by **Lee Sharp** » Fri Nov 16, 2007 4:54 am

Specs lie. You need to see an image. A high res crappy image is still crappy.

jameswilson · Post by **jameswilson** » Sat Nov 17, 2007 12:13 am

jimbojr · Post by **jimbojr** » Sun Nov 25, 2007 2:07 pm

Hi Guys,

thanks for the replies,

"No pro cameras do not put the ir emmitter on the cam, its a bad bad idea for many reasons but its cheap. Proper cams use a seperate emitter but these can cost from £100 to £500 depending on lens and power etc. Most people just use the led ones but personally i hate them (but i have one at home.... i fell for the theory too lol) "

Is having that IR emitter on the cam that bad? I suppose you may only get a narrow IR beam directly pointing from the the cam face, whereas with a seperate IR flood type thing you can illuminate more evenly over a wider angle/area....

I have another question for you guys, What about 'heated' cameras - I don't want the lens to freeze up so the cam can't see! My cheapo IR camera actually gets quite warm with the IR turned on, but for non heated non-ir bullet cams would freezing be a problem?

Lee Sharp · Post by **Lee Sharp** » Mon Nov 26, 2007 2:51 am

jimbojr wrote:Is having that IR emitter on the cam that bad? I suppose you may only get a narrow IR beam directly pointing from the the cam face, whereas with a seperate IR flood type thing you can illuminate more evenly over a wider angle/area....

I use them all the time. You have little range, and they take some power, which can be a problem on a long run. However, since I am not independently wealthy, the "cheap" factor makes a difference.

And you can always add an IR flood later to get the range, or cover a different region. And of course, they have a built in heater. (Not really a problem in Houston Texas that often)

tszodie · Post by **tszodie** » Fri Mar 07, 2008 10:52 pm

"I have another question for you guys, What about 'heated' cameras - I don't want the lens to freeze up so the cam can't see! My cheapo IR camera actually gets quite warm with the IR turned on, but for non heated non-ir bullet cams would freezing be a problem?"

It gets very cold here in Yellowknife and the cheap bullets have been fine outside to -60 no heat cases needed.

Depending on your aspect the beam can be effective in the cam good for a cam in your door or pointed @ a reflective surface (ie:snow here lol) distance is the biggest factor with IR IMHO. usually only about 3-11 feet.
& my $0.02 separate IR is a big plus perhaps Ill post hack my hack on how to remove, add parabolic reflector and extend your IR from cheapo type bullets