[quote:c32e2fdb21="wjemi"] ... I wonder if there is problem with IS, I still haven't work out. Could you please suggest some ways to test the IS or other functions? I can't leave it to Canon for 3 months. As I'm leaving in early May.[/quote]
Jemi,
My advice is to have IS switched off whenever shooting birds in flight as IS introduces some sort of time lag before it stablizes enough.
The EF300/4L IS incorporates a first-generation IS with a claimed gain of 2 f/stops for hand held photography. This can easily be verified shooting stationary subject handheld under relatively poor lighting conditions.
The IS system in this lens has 2 modes - one for static shooting (both horizontal and vertical stabilization) and a panning mode (horizontal or vertical stabilization - the panning direction is automatically detected). Unlike the 2nd generation IS used in EF400/2.8L IS, EF500/4L IS & EF600/4L IS the variant of the 300mm f/4 L IS has no tripod detection so IS needs to be switched off here in order to avoid interference effects.
Best and Good Shooting!
