Boeing 747-400 (N908AR)

Great photo Zhiren!

Thanks, John.

Left winglet looks at a strange angle compared to right winglet, surely not an optical illusion?

Looks like they have hydraulic control of the winglets. This is the setting for cross wind landings. Look at the weeds! HA HA

I guess it is because those winglets are tilted outwards rather than perfectly vertical, which makes them look strange from the back.

Winglets do not have hydraulic controls. They are mounted firmly on wing tips. Look at the two rotatable planes on the vertical tail wing. They are turned to the right a few degrees to compensate the minor crosswind.