Brian wrote via e-mail:
In my recent post (Gray Ghost vs RTH) you will see an exchange between Dan and I that raises a notable concern. I like my Sigma 500mm f4, as does his friend, but it seems there are no reliable TC options to extend range. Bummer. I had some exchange with Ari a week ago about Nikon vs Sigma and he said I might not see quite the sharpness as a Nikon. I pondered the 500 PF but he suggested not dropping down in aperture lenses. And that ultimately, most great bird photographers would own a 600mm f4E. That got me thinking.... With the Signa TC considerations (or lack of) I can return my Sigma until May 31. Do I reach for a gently used 500mm f4E paired with Nikon 1.4x or reach another $1k+ for a 600mm?
Hey again Brian, Not shocked by poor off-brand performance with a TC. I am curious: were you using the TC-E14?
I have been using and loving the 600mm f/4 lenses for well more than 25 years; I cannot live without one. And I have used all thre: Canon, Nikon, and now Sigma. I would return the Sigma in 1.6 seconds and go for a Nikon 600 f/4 if you are sure you wish to pursue this. Your early efforts have neen quite excellent. Another lesson from the blog and the books: the size of the bird in the frame is a function of the square of the focal length; i.e., six squared is 36, five squared is 25. So the size of the bird in the frame with a 600 is 9/25 greater than with a 500, i.e., 36% larger in the frame ...
I should have a near-mint Nikon 600 f/4 within a week as per my e-mail.
with love, and thanks for your membership support.
ps: the neear-wing position on the red-tail is an image wrecker on itsown.