Thanks Jay.
Re filter, you are absolutely right that the best way is to image when the object to be imaged is at its highest point. The reason why I am inquiring is that unfortunately, because of my job, I can't always be available when that occurs
. I often have to make do with evening observation/imaging. Furthermore, the Moon and Jupiter are not very high in the sky at the moment from Adelaide. So if a filter can help reduce poor seeing and improve my photos, even slightly, I would be happy to get one. Any suggestion in terms of brands/types?
Re cooling fan, is there any risk of vibrations from the fan affecting the imaging quality?
Cheers,
Eric