Thanks for the comments, kk!
After some recent field tests, I now feel very comfortable shooting with the 2x wide-open on the 1D3 (with micro-adjustments for the EF600/4). I can get essentially tack sharp flight shots with this combo provided I can track the subject properly (which I need more practise). And its AF speed with the 2x is quite decent too (much better compared with the 1D2). Just for these advantages, I think my upgrade to the 1D3 is very worthwhile... :wink:
Now my only problem is to find some birds to shoot.
ops: After we left NSW, we took a walk in MPNR and we were in for a shock! Most of the ponds were deserted! I thought we are now well into the birding season... :? We went to my favorite balcony opposite to the "duck" ponds. Apart from no ducks in the ponds, the balcony has also turned into a bird hide. Not sure if it is worthwhile anymore for raptor photography... our hobby is getting tougher and tougher in HK...
ops: