This is a collage from different out of focus images (either 10 or 30 second exposures) assembled to represent the eight extremities of the 35mm frame of my SBIG STL-11000M plus the center.
Each box is full resolution (click on "Original" below)
To my relatively novice eye, the collimation looks very good and the image appears balanced. Again, remember, this is out-of-the-box collimation. The stars from the system, as is, may display very slight elongation at the corners so some minor tweaking may be called for.
NOTE: To achieve this level of out of focus, the mirror spacing was reduced by 6mm from the optimum setting. The Atlas focuser was near it's maximum extent so these images are "inside" focus.