Im new to the whole lens business. but on the 250mm canon lens it it was sitting at approx 75mm on the lense.
I use nebulosity 2.0 works a treat and you can utilize dithering though PHD with it too.
The problem with Orion was that out of the 5 shots i took, i only used 2 10 min subs becaues the cover for the lens kept falling off without me seeing so
It looks like Shane, Dan and I will be out there this weekend aswell as they are predicting clear weather, the moon sets at just on midnight so it should't be too much of a issue.
allows a bit of a feed and check that everything is nice before I set for a run of 20 x 10 min shots or something silly like that.!