The Giottos MH7002-630 Ballhead is a single action ballhead suitable for travel use, with a 'snap-in' quick release system that's also got a bubble level right at the plate's location. It uses a simple single lever to lock and unlock all movement functions, and is rated to comfortably hold equipment weighing up to 11 lbs (5kg). You can use your SLR camera comfortably with a ~200mm lens.
The MH7002's strong locking lever can be adjusted so that the range of movement between locked and unlocked is wherever you prefer it to be; many heads cannot be adjusted in this way.
MH7002-630 Ballhead with Quick Release