What are webcam features I should be thinking about for a high performance webcam?

What features are important when looking at webcams.

If the webcam is for surveillance your primary focus are Indoor/Outdoor Ratings, Frame Rate, Resolution, Zoom Capability & Focus Type, Low Light function, RTSP & H2.64 Compression.

Indoor / Outdoor rating is important in colder climates and for being rated to handle rain and freezing.  Cheaper cams and lenses may lose focus on temperature changes.  You want to buy all outdoor rated equipment and check the low temperature ranges for your area weather.  Also if you are in a hot environment check the high temperature ratings as well.

Frame Rate should be at least 30 frames per second.  Important when objects are moving or moving fast.

Resolution should start at HD 1920x1080 and go up from 1MEG to 4MEG.  The higher the resolution the more you will be able to zoom in and see detail.  Chose the 4MEG or higher cam to try to capture a license plate.  Some modern AXIS cameras have built in detection software to ID license plates.

Zoom Capability & Focus Type needs will depend on if the webcam is Static shot or a Pan Tilt Zoom Dynamic shot.   In a PTZ shot the camera will have to dynamically recalibrate the focus and zoom.  In this case you will want the laser focus technology vs digital zoom from the image technology.  The laser is much faster and is a better option in PTZ cams that are on a viewing tour.  With a static camera you can work with the standard digital image zoom technology as you need only to set the focus one time.  In both cases you will be able to focus the webcam remotely without touching the lenses.  Zoom levels of 50X are available in  current models.

Low Light function us key for getting a decent night shot.  Lights in the area must be behind the webcam and not directly in the view at night.  Control of the exposure and low light settings is useful in getting the perfect night shot.  Keep the area lighted at night and adjust the webcam night setting to get the best view for the light conditions.  Moon light can greatly effect your nightly results as well.

RTSP & H2.64 Compression is required if you plan to stream to offsite servers and create a live public stream.