Lens warmers - How to stop camera lenses fogging up

In this video I share a tip I've been giving out for many years in my forum to stop camera lenses from fogging and misting up - to use Little Hotties disposable hand warmers. Getting condensation on your lenses is a real problem on damp UK evenings especially if your camera is out for a while (either for fireworks or for astrophotography).
These cheap warmers can be attached to lenses using elastic bands and with a bit of trial and error need not stop you using the focus and zoom rings. These have been 100% successful for me so far and are readily available online for example from Amazon.
In this video I show how they work and how to attach them to your lenses.
PS. They also make great hand warmers ;)