When people purchase bullet style security cameras they will sometimes run into an issue with them fogging up or having moisture inside the glass enclosure. This can be quite the nuisance as it makes it quite hard to get a quality video. I will address the steps necessary to try and solve this problem.
Before we start please be aware that the steps involved in this may possibly void your warranty, and it would be a good idea to talk with your surveillance equipment provider before beginning.
Remove the hood / sunshield if necessary.
Some bullet style security cameras, especially the outdoor cameras will have a hood or sunshield on top of them to help deal with the elements. You will first need to remove this shield. Generally these hoods will slide off, but it may require a bit of force as they are secured on rather tightly; also be sure that they are not screwed into the mount, and if they are remove the screw.
Unscrew the glass covering.
At the end of your bullet camera you will have a cap that can be screwed on and off. This cap contains your glass covering that is fogging up and it will need to be removed from your security camera. Be aware that an O-ring may be present to help with the sealing of the cap. Do NOT lose this O-ring.
Use a soft towel and some Rain-Ex.
Now that you have your end cap screwed off, you will need a soft towel that is not going to scratch the glass and a bit of Rain-Ex.
Take and apply the Rain-Ex to the glass cover as instructed from the bottle and make sure to dry it off thoroughly when done. Do NOT get any Rain-Ex in the surveillance camera itself.
This should be done in a cooler environment with relatively low humidity to have the best effect.
Re-assemble your surveillance camera.
Put your glass covering cap back on the bullet camera along with the O-ring if applicable; then reattach your hood and this should help solve your fogging issue.
Quick Overview For Defogging Your Bullet Camera
1. Unhook the sunshield / hood
2. Remove the glass covering cap end
3. Use a soft towel and apply Rain-Ex to the glass covering
4. Reassemble your surveillance camera
These steps will help prevent and fix any issues your bullet camera may have with fog on the glass covering. If the problem persists after doing this; you should consult a surveillance professional for further options.