There is a theory if you need to recognize somebody you know you should have at least 40 pixels/foot (vertical) and you need 60 pixels per foot in case if you want to identify somebody you don't know.

So if you have 1.3 Megapixel camera with 1/2" sensor format and 8 mm lens you are going to have 42 pixels/foot at 40 foot from camera and width of the field of view 31 ft.

If you need more (like 60 pixels/ft) you can put lens with higher lens focal length (12 mm, with 19.9ft) or put 3 Megapixel camera.

In case if you would have a 3Megapixel camera

Response:

If you want something that definitely works and is very high end, please take a look at our megapixel cameras:

http://www.cctvcamerapros.com/Megapixel-IP-Cameras-s/343.htm

These work with these stand alone NVRs:
http://www.cctvcamerapros.com/Network-Video-Recorder-s/299.htm

or with this PC software:
http://www.cctvcamerapros.com/NUUO-IP-Camera-Software-s/297.htm

You can watch some videos online about the NUUO software here:
http://www.cctvcamerapros.com/NUUO-Surveillance-Systems-s/296.htm#videos

I’m considering a security camera system for my home and hope you will help. I want cameras with enough “resolution?” so that I can recognize / identify someone at 30-40 ft. Most of the small system I’ve seen for home use are “useless” in that the resolution is so poor at a distance you can’t see faces just blurry figures. I doubt anyone with bad intentions will walk up and look in the camera at 3-4 ft. What type of outdoor cameras should I be considering.

Thank You,
Joe & Barbie R.