The little ST-8300 CCD camera proved to be a nice performer, however, in our rather wet climate I started to be plagued by dew formation. Initially, I though that the CCD chamber was somehow leaking or captured moisture. Only after searching some on-line forums I have discovered that I am most likely experiencing dew forming OUTSIDE CCD chamber, on the chamber window!

A quick cure was to install a pair of 1W heaters inside the filter wheel, on the plate facing camera. This way, the entire plate is slightly warmed, causing also the air inside CCD camera (in front of the CCD chamber window, off course) to slightly warm, which prevents dew.

After that, I have also acquired a heater strip from SBIG which is to be glued to the CCD chamber front cover and powered internally from the camera - which I elected to skip for a time being.

Initial testing proved successful, with no dew forming on the CCD chamber window after few hours of use. However, more tests and in more humid conditions are now needed to confirm that the problem was fully resolved.

UPDATE

The approach of heating the filter wheel back plate facing camera proved successful, with no signs of dew anymore.

However, there was an excessive noise in some images observed, when the dew strips were connected to my PWM dew controller. As a result, I decided to modify the setup. The cables were re-soldered, so now heater strips are connected in series - the power dissipated is reduced to 1/4 but it is still enough to prevent dew formation. With higher resistance of the heater, it is now permanently connected to 12V "quiet" power supply to prevent any noise from entering the camera.