Here's an example of why good tracking is important.
Taken on a breezy night out the left image is a stack of the best 4 subs: 4 x 4mins. The right image is a stack of the best 10 subs: 10 x 4mins.
Discarding 6 subs gives a nicer end result. The left one is reduced somewhat, but you get the idea. Just look at the shape of the stars and the clearer image in the core.
Of 23 x 4 mins of subs only 4 had near-round stars. 19x4 (76) mins of data wasted....
Frustrating, what?
I can just imagine the result with 76 minutes of good data...
.
How does a Losmandy G-11 handle a breeze ?