CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
Remus,
I would take the camera apart and check the Orings for nicks. That may be were you are getting a slow seepage of humid outside air. + are you sure the frosting is INSIDE the chamber? The window can frost up on the outside as well. In fact, the STL series now includes a small heater for the window iirc. Some folks down in FL had issues with frost on the outside of the window.