Well, sometimes you just can't win for anything...
I spent a long time carefully focusing and framing a wide field shot of M8 (the lagoon), M20 (the trifid), and M21 (an open cluster whose name escapes me at the moment). Here is the test shot that convinced me to shoot:
As luck would have it, before starting my sequence of light frames I stepped away from the camera for a few minutes. When I returned to the camera I discovered that my lens (135-400mm zoom at 400mm) had completely fogged over.
I borrowed Fred’s dew dryer and de-fogged my lens, then immediately started taking my lights to try and get as many in as possible before the lens started to dew over again. I took 15 four minute frames (a total of an hour) before starting to break down, as it was really early and the night was winding down.
I should have taken a few minutes out to re-check my framing and focus:
Somehow during the de-fogging of my lens I both moved the camera (haven’t figured that one out yet) and bumped into the lens and changed its focus! Ruined the shot!
I have to say it wasn’t a total loss – I did have fun taking the blurry picture and I’m happy to say that my tracking was pretty darn good at four minutes and no guiding. I’m also learning more about post processing all the time. And I was very pleased to find that my dark frames perfectly removed all the latent noise and amp glow in my subs. The trick is to take them at as close to the same temperature that you took the lights as possible, and Wednesday night’s weather cooperated well in that department – pretty much hot all night!