Sidewinder 10-50x60 tmx - Hawke Sport Optics Sidewinder 30 ED 10-50x60 TMX IR Rifle Scope 30mm Tube Second Focal Plane

Hi I have an Hawke sidewinder10-50x60 ED tmx with 1/8 MOA turrets put on a .22. My hole whole picture looks great but when I'm zero on 75m there is a slight cloud that shows at the bottom of the scope any reason why I've seen that the deeper your turret is turn for elevation your picture changes and then there is no cloud. As if your background picture changes with the rectical