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Lens' and field of vison
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Topic: Lens' and field of vison (Read 2775 times)
DEViANCE
Posts: 3,519
Hero Member
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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Rutabaga
Posts: 6,324
Global Moderator
Hero Member
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.
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DEViANCE
Posts: 3,519
Hero Member
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.
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DEViANCE
Posts: 3,519
Hero Member
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.
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Russell
Posts: 1,124
Hero Member
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.
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Mongoose
Posts: 3,102
Hero Member
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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Lens' and field of vison