That's very clear.
I have a 10" Dobsonian telescope and although it is resistant to dew formation due to the mirror being a long way down the tube, there are still times when I have to just give up as the moisture will get down even there eventually. The only real way of condensation prevention is heating. With a telescope you can buy mirror heaters, although the eyepieces can still mist up. With a camera I might suggest a hair dryer applied lightly every few minutes, just enough to keep the condensation off, but of course nowhere near enough to heat up the objective glass.