best budget lens for bird photography

arka_prava wrote:

hi,

i am new to dslr and currently own a d5100 with 18-105mm vr. but to nurture my newfound interest in wildlife and bird photography i want a zoom lens. i have tried the nikkor 70-300mm vr(belongs to one of my friends),i am pretty impressed with the sharpness but not with the reach, i want something a bit longer,so i am considering the following options

1) sigma 150-500mm os

2)sigma 120-400mm

3)nikon 300mm f/4 with teleconverter

which one will be best for me. i am inclined to a zoom lens because of more versatility. new options are most welcome.thank you

Regards

Arka