My new ASI 071 is also dewing @ -10C. I was in a strong humidity weather > 80%...
It's seems to be on the external side as i've no frost on the sensor mainly a dew behavior ...
Maybe the camera internal heater is undersized ?
As i saw this message before purchase, i also add the zwo 1600 dew heater to the combo.
But a major flaw is that the dew heater cover the tilt screw adjustment on the ASI 071 + It's ugly !
I ve conducted further experimentation with my brand new camera yesterday.
I was @home with a very low humidity and i drive the cam @ -10C in 20 minutes....
The TEC never run at more than 42%
=> What i see is not on the front windows, it's dew on the sensor
(And since it's on the sensor, the additionnal dew heater is useless.)
So i run the TEC for 0°C for about 15 minutes and the dew fade away.
I shoot some dark for 1 hour @ 0° running the TEC @ 15%
Then after that, i cool down again @ -10°C in 10 minutes. The dew this time does'nt came back.
But i've not run the Camera for a long time as i need some sleep...
As the camera is new, i would avoid to install the desicant tube for now.
This operation will break the camera sealing and expose the camera to ambiant air.
When the desicant tube is installed, i understand that it must rest in place ?
Any suggestion ?