HEAVY ARTILLERY. The 350D + Sigmonster + Canon 2x TC struggles to bring the distant ducks closer.... even 1600 mm was not enough firepower to make the birds full frame.
Impressive set up! I love your Gimbel head, it seems to be very steady. Am planning to buy a used Nikon 400mm f2.8 which is pretty heavy. Would that tripod and head be a good solution. Love your bird shots, quite different from my Provence garden variety...Peter Clark