how can i select the lens?

what is the realtion between focal lens, fov, and Zoom( no. of X optical zoom)

Get a Varifocal lens and make life easy.

http://en.wikipedia.org/wiki/Lens_makers_equation
http://en.wikipedia.org/wiki/Optical_coating
http://en.wikipedia.org/wiki/Back_focal_plane#Focal_points_and_planes
http://en.wikipedia.org/wiki/F-number
http://en.wikipedia.org/wiki/Lux
http://en.wikipedia.org/wiki/Fabrication_and_testing_of_optical_components
http://www.mrpinhole.com/calcpinh.php

FISHEYE
http://en.wikipedia.org/wiki/Fisheye_lens
ZOOM
http://en.wikipedia.org/wiki/Zoom_lens
VARI FOCAL
http://en.wikipedia.org/wiki/Varifocal_len
TELEPHOTO
http://en.wikipedia.org/wiki/Telephoto_lens
What is inside of a zoom lens
http://www.adaptall-2.com/articles/InsideZoomLens/InsideZoomLens.html


The lower the mm number the wider the viewing angle.

The higher the mm number the more zoom factor you have.

6mm is your starting point.

The 4mm is a wide angle lens. 4mm and 3.8 are easy to make, and are most common on off the shelf cameras such as bullet cameras, and "DVR kits in a box".

2.8 is a Fisheye lens.


Camera Variables that effect picture quality regardless of lens:
chipsets used for the camera "eye"
WDR
Matching the camera to the DVR (native camera size verses native DVR size)

Lens selection that effect picture quality:
Plastic verses glass lens.
Quality of glass grinding to achieve lens shape
Lens Coating to achieve extra quality such as reduced glare ect.


http://scorpiontheater.com/camlab.aspx

The post above shows it is not easy to select lens.

I use software utility ver. 5.3 from http://www.jvsg.com
- you see what you get because of 3D-preview.
- you have exact calulations of focal length, field of view, angles and other staff.

It does make sense to have a look. :)

My portable test monitor has a built in camera with selectable lenses,, kinda makes life easy but usually use varifocal anyway.

Hi, ipman

Thanks for your recommendation. This lens software is what I was looking for!

There is one easier :)
http://www.dallmeier-electronic.com/en/products-electronic/cameras/view-designer.html

Well, Robert I am not agree.
I would say the View Designer is too basic.
It even calculates horizontal projection wrongly.
Lets make a small test:

Camera Installation Height = 6.5 m
Sensor Size = 1/3"
Lens focal length = 4 mm
Distance = 10 m
Object size = 1.8 m, like here

Let's see horizontal projection in "IP Video System Design Tool 5.3", "Video Cad6" and "View Designer 1.0".

Additionally imagine you put a 1.8m tall man at 4m distance from camera and 3.3m on the right (orange man - in JVSG at mouse cursor position).





As you can see man at (4m; 3.3m) is visible but View Designer shows the max right position at 4.5m/2 = 2.25 m. But it is not correct.

Please download JVSG tool and compare results yourself.

Looks nice software, downloaded, tried, looking good for lenses, but not so good for storage calculation and network bandwidth as its shows completely different numbers compared to Arecont Vision calculations.

But yes, difference is quite a bit :shock:

It would be an offtopic here, but I have made a test of BW calculation with Arecont and Axis calc:



I would say BW&HDD space estimations are surprisingly accurate

Well, I got something different. Any ideas why?



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Robert, it looks like the trick is in arecont "% Motion Detection Activity" parameter. On your arecont screenshot you have option "50% motion activity" selected. But in the IP Video Tool you have 100% recording.

You can just specify "50%" recording activity and get almost the same result - BW: 33.9 MBit (32) HDD:2.5TB (2.4)