Autumn in temperate climes brings one of the amateur astronomer’s big problems – dew. As the temperature of telescopes drops, water vapour condenses on the glass surfaces making observing very difficult.
Dew shields can delay its formation and you can buy special battery-powered tapes for many telescopes to help prevent it forming but they tend to be expensive.
One way round the problem is to take your telescope into a warm room for a while, if possible, and pop your eyepieces into a warm pocket between uses to keep them dry.
But another tip to to buy a portable hairdryer that will run from a 12 volt battery. A quick blast from time to time will be enough to warm your optics and clear the dew, allowing you to carry on observing.
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