Author Topic: Lens' and field of vison  (Read 2773 times)

Lens' and field of vison
on: September 11, 2012, 18:31:24 PM
Can anyone help me out, I'm currently spec'ing a job for some CCTV cameras for a really paranoid, really rich person. He only wants a 4 camera system but wants as close to 100% coverage as possible.
 
I stupidly suggested drawing a diagram for him with the positions of the cameras on the house and their approx field's of view so he can see any possible blind spots.

So I need to way to workout with the size & type of lens on the camera what view that camera will have.

Anyone point me in the right direction?


one of the camera's I'm looking at has a 3.6mm lens and the other 2.8-12mm Varifocal Lens.

Cheers
Rob

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Re: Lens' and field of vison
Reply #1 on: September 11, 2012, 18:58:39 PM
I only know that a small apature gives better depth of field :) so I guess the lens which give the best light would be best.

Re: Lens' and field of vison
Reply #2 on: September 11, 2012, 19:05:05 PM
all the cameras I use have 1/3" ccd's if that matters and use the lens I mentioned above. There must be a formula to work out the 'cone' view of the camera.

this is what I want, but with reletively accurate cones.

Re: Lens' and field of vison
Reply #3 on: September 11, 2012, 20:41:14 PM
Think I have found it.

distance x 4.8 / width of view

so if I want to see 18m away and a 21m wide picture I need a 4.1mm lens.

Re: Lens' and field of vison
Reply #4 on: September 11, 2012, 22:16:16 PM
Good job, I've got no idea!  Only lens I've got I know the field of view for is my Sigma 10-20mm which is about 110 degrees but I couldn't tell you how I know that or how to work it out either.

Re: Lens' and field of vison
Reply #5 on: September 25, 2012, 08:39:56 AM
this looks handy

http://www.pelco.com/sites/global/en/sales-and-support/downloads-and-tools/tools/lens-calc.page

I'm guessing you've got drawing software for this, but if not I find QCADs free version works well enough for simple 2D sketches.
Last Edit: September 25, 2012, 08:41:33 AM by Mongoose #187;

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