Hi guys - new poster. Great site, lots of useful information. 
I have a question I hope you can help with. 
We are using Watec 902H2 Supreme to monitor a street scene day and night in a city area. We are not using an IR illuminator. Should we be using an IR Corrected Lens rather than a regular varifocal to avoid focus shift? 
  
Many Thanks 
  
OMD