USB 2ndry Mirror Dew Heater & also Newtonian primary & other beginner questions...

[chrispj]

It's cold,  it's my first winter of astronomy and so I've encountered dew for the first time,  dismayingly early in the evening!

 

I've seen the threads mentioning usb dew heaters,  which are perfect as I have acquired several power packs over the years. The heaters are all though of the type marketed for camera lenses so good for the refractors but not so good for a 10" Newtonian!

 

So the question is does anyone know of a suitable heater for the secondary mirror that can be powered by 5V USB? 

 

Also I noticed after bringing the scope back inside (to a cold garage) the primary mirror had fogged up,  not sure if this happened just before or after coming indoors. Is it typical to use a heater for the primary? There is a fan also (see below),  I don't have a power pack/cable for it,  would this be effective at keeping dew off? In which case can anyone point me towards the right battery box or else a cable to connect to usb?

I see most dew heaters run off 12V but as I already have the 5V power packs I'd rather not have to splash out on a full 12V system if I don't have to!

 

One final question,  given last night's experience I take it its typical to run heaters on telescope,  eyepiece and finder? 

Thanks all. 

 

 

 

[malc-c]

I remember seeing a DIY system which used high wattage power resistors which were glued to the back of the secondary, with the wires run along the veins of the spider that supported the secondary.  I can't remember how well it worked, or if the wires caused any degradation or artefacts in the final image 

[Guest]

Depending on your environmental conditions you might try making a dew shield.  They are easy to make and cheap.  If that doesn't solve the problem then you are talking dew heaters.  I live in Ohio and dew/frost/ice are killers.  The dew heaters I use wrap around the end of the finder and main scope.  I run the Orion Dew Zapper system and dew/frost/ice are no longer an issue.  I will eventually be buying a strap for two inch eyepieces.