Cctv Format

[Guest anguscanplay]

I'm just curious where that 0.6 metre figure comes from ...?

What imager format, lens focal length, aperture setting ..... ?

Unless I've been studying the wrong principles of optics for the last thirty something years, then depth of field really should not be an issue for the primary recognition zone on a 20 metre driveway. IMHO It's eminently do-able provided the camera is tasked to fulfil a specific purpose.

your seriously saying I`m going to as recognisable at 20mtrs as i am at 5mtrs? lets just assume the ubiqutes (?) 3.6mm lens shall we?

try this one - we wanna know who was driving the van ( as well as read the number plate of anyone using the drive to turn round on)

[billythebellbox]

try this one - we wanna know who was driving the van

the flying dutchman aka Van Driver?

[james.wilson]

lets just assume the ubiqutes (?) 3.6mm lens shall we?

why, only bullet/dome cameras come with that.

Out of interest what is your most used camera/lens combo externally as your using that pic?

[Guest anguscanplay]

why, only bullet/dome cameras come with that.

Out of interest what is your most used camera/lens combo externally as your using that pic?

IIRC thats the "sony, sanyo, system Q, VCL ........." day night dome cheap thingy that Pete likes, the example I`m trying to make is that that is the kind of thing most users will end up with and to them at first viewing its the business, until like this case they actually wanted to use the footage - we`ve got a van thats familiar enough but thats all (and before you say zoom in then, 30mph at that distance - one frame maybe 2 of an even more blurred van?)

now if the system had been sold purely on the basis that it covered the car door - thats what I`m trying to say

[Doktor Jon]

liver shot?

... brain actually

[Doktor Jon]

your seriously saying I`m going to as recognisable at 20mtrs as i am at 5mtrs? lets just assume the ubiqutes (?) 3.6mm lens shall we?

Why should I assume a 3.6mm lens ...?

Apart from all the detailed planning preperations that go before, the first practical step is to decide where best to place the camera to achieve the objective. Then select the most appropriate camera and lens combination to produce the quality of image that is required within the primary recognition zone. Then set up the camera / lens + any additional lighting required, to make sure it's doing exactly what is intended.

Now unless I'm very much mistaken, most bullet or miniature cameras with a 3.6mm lens fitted, tend to use a "barrel" design with fixed aperture, so how is it going to be possible to manipulate the iris in order to vary the "Depth of Field", to achieve the desired result?

As for what would be the most appropriate focal length lens required to achieve the objective .... well, I couldn't possibly ....

[Guest anguscanplay]

Why should I assume a 3.6mm lens ...?

Apart from all the detailed planning preperations that go before, the first practical step is to decide where best to place the camera to achieve the objective. Then select the most appropriate camera and lens combination to produce the quality of image that is required within the primary recognition zone. Then set up the camera / lens + any additional lighting required, to make sure it's doing exactly what is intended.

Now unless I'm very much mistaken, most bullet or miniature cameras with a 3.6mm lens fitted, tend to use a "barrel" design with fixed aperture, so how is it going to be possible to manipulate the iris in order to vary the "Depth of Field", to achieve the desired result?

As for what would be the most appropriate focal length lens required to achieve the objective .... well, I couldn't possibly ....

so its like I said then - you can`t ID me at every point of the drive

the problem isnt the equipment, its the user expectation

[ilkie]

so its like I said then - you can`t ID me at every point of the drive

the problem isnt the equipment, its the user expectation

You cannot ID a person everywhere in the drive with a bullet camera equipped 3.6mm lens, just like you cannot drill through a concrete wall with a food mixer. The wrong tool for the job.

You can specify a camera that will ID someone anywhere in the drive, or you can specify a camera that will ID at a pinch point in the surveillance area (and and then also add cameras to the system that provide nice wide angle shots for general surveillance as well).

Each choice will have an impact on camera numbers and budgets and it is up to the industry to come up with the best fit for as many of the requirements as possible, without loosing sight of one of the main purposes of public area CCTV is to provide evidence in accordance with best practice, legislation and guidelines. (just like it is the alarm industry's job to provide a system that correctly detects intruders and rings the bells, again in accordance with the regs etc.)

A professional security company would no more install an alarm that they would know from the outset would not detect nor should they install a CCTV system that will not provide best evidence, even if the the end users instructs (through lack of knowledge) otherwise.

It's all about education and if necessary regulation

Ilkie

[Guest anguscanplay]

You cannot ID a person everywhere in the drive with a bullet camera equipped 3.6mm lens, just like you cannot drill through a concrete wall with a food mixer. The wrong tool for the job.

You can specify a camera that will ID someone anywhere in the drive, or you can specify a camera that will ID at a pinch point in the surveillance area (and and then also add cameras to the system that provide nice wide angle shots for general surveillance as well).

Each choice will have an impact on camera numbers and budgets and it is up to the industry to come up with the best fit for as many of the requirements as possible, without loosing sight of one of the main purposes of public area CCTV is to provide evidence in accordance with best practice, legislation and guidelines. (just like it is the alarm industry's job to provide a system that correctly detects intruders and rings the bells, again in accordance with the regs etc.)

A professional security company would no more install an alarm that they would know from the outset would not detect nor should they install a CCTV system that will not provide best evidence, even if the the end users instructs (through lack of knowledge) otherwise.

It's all about education and if necessary regulation

Ilkie

I like you Ilkie (no really i do LOL) but you said that before and I asked you how would you achieve it which you havn`t been able to answer, and thats my beef with this topic - best evidence just isnt good enough.

[ilkie]

I like you Ilkie (no really i do LOL) but you said that before and I asked you how would you achieve it which you havn`t been able to answer, and thats my beef with this topic - best evidence just isnt good enough.

Thanks for the response Angus.

If you are asking me to design a system that provides recognition anywhere in your drive I can do this.

If you are concerned that a camera system will not provide recognition if the target is wearing a hood/hat/mask or paper bag over their head you are, of course correct.

Nevertheless, this is not a reason to not design the system around best practice, as not all 'targets' were hoods etc.

So to detect an incident that may occur anywhere within a large area, such as vandalism or theft from a car park, a series of wide-angle cameras may be appropriate (i.e. a camera with a large FoV).

These are also often presented as a cost-effective solution, as fewer cameras will be needed to cover the whole area.

If so employed they should ideally be spaced closely enough to ensure that any person approaching within the selected area was observed by at least one camera and was visible on the monitor at a minimum of 10% screen height, enabling them to be detected by the operator.

However, utilising only wide-angle cameras may not provide sufficient detail to enable an individual to be identified. Thus it may be necessary to include at least one camera that can capture more detailed information (i.e. obtain a clear shot of a face or car registration plate).

The best place to site a camera for identification purposes may be a