Taking flats and focus

[Catanonia]

I was going to take some dusk sky flats before the imaging session tonight but am wary as I have not focused precisely the scope yet as there are no stars out to focus on.

How do you guys go about this, keep the focus from the previous night ?

[dugpatrick]

Yes, it's best to focus first and then take flats. But I often use the "pencil" method: I mark the focus point on my focuser tube with a pencil and then I can get flats that are ~kind of close. (but not perfect)

When Venus is out I focus on Venus and then take flats with the remaining daylight.

Doug