In case you are using the WPF RadCarousel you should set IsOpacityEnabled to false to disable the opacity effect. In case you are using the Winforms carousel please report this in the Winforms forums.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items