hello everyone. Its almost been an year , i am playing hard with my camera canon 550d and 55-250mm lense, shooting mainly birds. since i want to click birds while in flight, with absolute clarity and what we call it appropriate DOF...some suggested me buy a canon L lense. so my question is very simple(a bit stupid i guess), do i need to spend money on buying new lense exclusivly for birds? or canon 55-250mm would work well? i haven't tasted success till now with this lense shooting birds in flight. may be i need to work on my skills?