Comparison between 300mm f/4 prime with 1.4x TC vs 200-500mm f/5.6 for birds photography

DaveyJ

My thanks to Harold! Pistnbroke is undoubtably right about fine focus adjust!

Pistnbroke

Just been testing my "new" $130 sigma 300mm f4 (not HSM or VR) with and without a kenko 1.4 teleconverter. Same test object for with and without at f8/ zoomed in 150% on the without image and 100% on the with image. With the converter the image was only just slightly worse than the without so I sent it back for a refund. I argue that with it attached the camera shake will result in less keepers.
Using the Tamron 150-600 G1 the image was superior but the converter would not give autofocus with that lens.