Richard136

Thanks, Neil. Sounds like a different experience to the others if you are getting inner condensation. Love to see a pic of the objective after the dewing has gone, if possible please.

Thanks, all. So this sounds like I'm concerned over nothing. Good to know. What then is the general practice with dew heaters?: - turn on the lowest useful setting to prevent dew whilst scope is outside. How warm do they get and doesn't this heating creates thermal currents in the tube? - leave the heater on when bringing the scope inside after observing(?) I'm assuming the heater does not prevent dewing-up when bringing the scope back indoors, i.e. it doesn't heat it up that much. I'm clear on the points about not packing the scope away whilst wet; that makes total sense.

Hi. I am getting a second hand triplet refractor. It's air spaced. I am concerned about the potential effects of dew between the elements of the objective. Concern is along the lines of: - dew builds up on all cold surfaces, including presumably the inner surfaces in the overall objective. - dirt, water marks etc condense on the inner faces. - it's not practical to clean these inner faces. - potentially leaves an uncleanable lense Is this concern grounded or off base? I don't have a dew heater yet. I'll get one of course. The question is do I need one for the care of the objective in terms of dew, or just to extend observing sessions. Thanks for the advice. R