Making your Own Dew Heater
Moisture condenses on cold objects and forms dew, and hence a dew heater is an easy solution to this problem. The problem of dew condensation is more pronounced when you are shooting in a cold climate, and the film of moisture can ruin your shot and also the photographic equipment. Here is how you can make your own dew heater.
Step 1: Gathering Materials
The main materials you will need are resistors, rubber electric tape, battery and wires. The number of resistors you need will depend on the amount of heat you want to produce. This will again depend on your equipment and the degree of cold you will be facing on your shoot. For this example, we will assume you need 3 watts of heat and eight, one watt resistors. You will also need a soldering iron for joining the resistors with the wire.
Step 2: Wiring the Resistors
The eight resistors should be in a series and wired accordingly with equal spacing between them. The wires need to be wrapped in the insulation tape to prevent any mishap due to a short circuit. The idea is to form a circular ring around the optical element you are trying to heat up to prevent dew. So, you need to space your resistors accordingly so that the ring fits snugly around the equipment and is nearer to the glass.
Step 3: Connecting the Battery
Connect the series of resistors to a 12 volt battery, and you can expect 3 watts of heat for around four hours.