Appreciable difference over the 70-300 vr

What do you shoot, and how much do you crop?

Once I found a few birds (hawks, owls) I wanted to shoot, I found out all about not ever having enough focal range.    I also found that shooting at focal ranges past 200-300mm really takes better technique.    AND, there isn't all that much difference between 300 and 400mm, and less difference between 400 and 500.

That said, a 300F4 with 1.4TC will get you significantly more reach than you have, and the 300F4 by itself should be noticeably sharper than your 70-300.

I have both 80-400vr and 300F4 with Nikon 1.4TC.     The 80-400 is nicely sharp around 300mm, but it drops off considerably at 400.   It's simply never sharp wide open, but it can give nice results stopped down to F8-F9 there.   The 300+1.4 is better, and it's better at wider apertures.

From the results I've seen, the Sigma 50-500 is a bit better than the 80-400vr.   I don't think any of the other Sigmas are actually better, though the VR (VC) on them probably is.

Anyway, depending on what you are shooting, a longer lens may be worth getting, or it may not be.   It's certainly a lot more work shooting anything at 400mm and getting consistently good results than handholding a 70-300vr.

--
Craig
www.cjcphoto.net