I have installed a vandal resistant weatherproof varifocal dome camera containing a built-in external zoom and focal adjustment supplied by Max Security. The camera is in a coastal environment (15m to sea shore) on a second story deck. The camera is placed to survey the front of a private property address and identify colour and type of vehicles passing the location. Camera is set to record on motion and is unfortunately recording a lot of sessions of rain that tends to pass (almost) horizontally. Are there any tips or tricks to maximising legitimate activity in the area and minimising the capture of rain and the like in such an exposed environment?

Key Features:
4-9mm Varifocal Lens (Zoom)
Built-in Lens Separator
1/3" Colour Sony CCD Chipset
External Zoom & Focal Adjustment (Key Included)
420 TV Lines

36 Infrared LEDs
IP Rating IP66

The inherent problem with most economical DVR's is the motion detection software is not true motion detection, as it only looks for shift in the image (pels), so if a cloud passes by, or a bird, etc, the DVR tells the system to record.

So in your case, it doesn't matter whether you have a $100 camera or a $1000 one, you going to see the same results or lack of!

If anything, play around with camera placement and the sensitivity of your motion detection software.

You could look into using an outdoor PIR sensor to trigger the recording.

Optex Redwalls are common in the UK, they are pretty much just a waterproof passive infra red sensor, they use them in our local park, on building sites etc to trigger the ptzs to certain locations when someone enters the sensors field of view.