I need help.

[D50birdshooter]

I have a nikon D50 and i have seen amazing results with sigma 50-500mm is this a lens worth considering if it fits my budget perfectly or is the nikon 400mm zoom lens better i need help deciding right now. i am about to go on a trip to san fran sisco and i am wondering if i should go ahead and get it. Or should i get the tamron 500mm zoom. i wish i could get a prime but expenses are not working and i need a good walk around birding lens i am not going to get the 300 nikkor with a tc so that is ruled out.
please help me decide with your expieriences. Or should i go to canon and get the 30d with a 400mm F5.6 or 100-400mm IS

[pduxon]

you may want to look at the new sigma 150-500 and 120-400 lenses as both has image stabilisation. In preference to the old 50-500 and both HSM motors.

I'm not convinced that the Nikon 80-400 takes significantly better images than the Tamron but the VR means you get more photos you can use and is better for hand holding. Its marginally faster as well across the shared focal length.